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I 


THE    PRACTICAL 

METAL-WORKER'S  ASSISTANT: 


OMPRISINO 


METALLURGIC    CHEMISTRY,  THE    ARTS    OP    WORKING    ALL    METALS   AND    ALLOYS,  FORGING    OF 

IRON  AND    STEKL,    HARDENING  AND    TEMPERING,  MELTING  AND  MIXING,  CASTING  AND 

FOUNDING,    WORKS    IN    SHEET   METAL,    THE    PROCESSES    DEPENDENT  ON  THE 

DUCTILITY    OF   TUB     METALS,    SOLDERING,    AND    THE     MOST    IMPROVED 

PROCESSES,     AND     TOOLS     EMPLOYED     BY     MF.TAL-WORKERS. 


APPLICATION  OF  THE  ART  OF  ELECTRO-METALLURGY 


TO 


.  MANUFACTURING   PROCESSES: 

COLLECTED  PROM 

ORIGINAL    SOURCES,    AND    FROM    THE     WORKS    OF     HOLTZAPFFEL, 
BERGERON,   LEUPOLD,   PLUMIER,   NAPIER,   AND   OTHERS. 


OLIVER    BYRNE. 

\x 

A  NEW,  REVISED,  AND  IMPROVED  EDITION,  WITH  ADDITIONS  BY 

JOHN   SCOFFERN,  M.  B.,  WILLIAM   CLAY,  WILLIAM   FAIRBAIRN,   P.  E.  S., 
AND  JAMES  NAPIER. 

With  Five  Hundred  and  Ninety-two  Engravings,  illustrating  every  Branch  of  the  Subject. 


PHILADELPHIA 

HENRY     CAREY     BAIRD, 

INDUSTRIAL    PUBLISHER, 

406    WALNUT    STREET. 

CHICAGO :  JOHN  A.  NORTON,  126*  DEARBORN  ST. 

1864. 


Entered  according  to  Act  of  Congress,  in  the  year  1864,  by 

HENRY    CAREY    BAIRD, 

In  the  Office  of  the  Clerk  of  the  District  Court  in  and  for  the  Eastern    District 
of  Pennsylvania. 


STEREOTYPED   BY   8.    A.    OEOR8E, 

607   6ANSOM   STREET,   PHILADELPHIA. 

COLLINS,   PRINTER. 


PREFACE. 


"THE  PRACTICAL  METAL-WORKER'S  ASSISTANT,"  as  now  pre- 
sented to  the  public,  is  a  new,  revised,  and  very  much  enlarged, 
and,  it  is  believed,  greatly  improved  edition  of  a  work  issued  from 
the  press  of  the  present  publisher  several  years  since.  The  vol- 
ume, as  then  published,  was  received  at  that  time  with  great  favor 
by  practical  men,  and,  although  the  edition  has  been  entirely  ex- 
hausted for  many  months,  the  demand  for  it  has  continued  un- 
abated. This  demand,  and  the  consciousness  of  the  great  value 
of  the  book,  with  the  knowledge  that  it  will  fill  a  want  much  felt 
at  this  day,  have  combined  in  influencing  the  present  publication. 

Besides  the  revisal  of  the  text  generally,  entire  and  valuable 
new  chapters  have  been  added  to  the  book,  among  which  may  be 
named  the  following :  "  On  Metallurgic  Chemistry"  and  "  Special 
Metallurgic  Operations,"  by  John  Scoffern,  M.  B. ;  "Kecently 
Patented  Refining  Processes ;"  "  Wrought-Iron  in  Large  Masses," 
by  William  Clay;  "Application  of  Iron  to  Ship-Building,"  by 
William  Fairbairn,  and  several  on  the  various  branches  of 
Electro-Metallurgy.  It  is  believed  that  that  on  Recently  Patented 
Eefining  Processes  will-  be  found  especially  interesting  and  im- 
portant, on  account  of  the  extended  statement  therein  given  of 
the  details  of  Mr.  Bessemer's  Process  of  Refining  Iron. 

PHILADELPHIA.  MARCH  1  1864. 

(7) 


CONTENTS. 


CHAPTER  I. 

ON   METALLURGIC   CHEMISTRY. 

The  useful  metals  and  metallic  ores 

defined 17 

History  of  metallurgy 19 

Refining  processes 22 

New  refining  processes 23 

Adrantages  of  cast-iron 25 

Crystallizing  tendency  of  wrought- 

iron  in  large  masses 26 

Classification  of  metals 27 

Alloys 28 

Affinity  of  metals J 29 

Theory  of  alloys 30 

Metallic  oxides 31 

Reduction  of  metallic  oxides 32 

Carburetted  hydrogen 33 

Sulphides 34 

Chlorides 35 

Calcination  and  roasting 36 

Carburets  and  carbons 37 

Metallic  salts : 38 

CHAPTER  II. 

SPECIAL   METALLURGIC   OPERATIONS. 

Volatile  combinations 39 

Metallic  distillation  processes 39 

Fluxes  and  Fluxing 42 

Furnaces 44 

The  combustive  function 45 

Products  of  combustion 47 

Natural  and  artificial  blasts 50 

Blast  machines 52 

Catalan  trompe 54 

Chain  blast 55 

The  Cagniardelle 56 

CHAPTER  III. 

RECENTLY -PATENTED    REFINING   PRO- 
CESSES. 

Plant's  process 57 

Martien's  process 58 

Clay's  process 59 

Bessemer's  process 60 

Bessemer's  converting  vessel 62 

Application  of  the  tuyeres 64 

Pouring  out  the  Suid  metal 65 

Preparing  the  vessel 66 


Process  of  conversion  explained..  67 

Bessemer's  squeezers 69 

Bessemer's  hammer  and  guage 70 

Analysis  of  Bessemer's  iron 71 

Analysis  of  ordinary  puddle-iron.  72 

Reflections  on  Bessemer's  process  73 

CHAPTER  IV. 

REFINING  AND   WORKING   OF   IRON. 

Iron-furnaces  in  the  United  States  75 
Dickerson's    method    of   making 
wrought-iron  directly  from  the 

ore 75 

Manufacture  of  malleable  iron 77 

Puddling 77 

Winslow's  machine  for  compress- 
ing puddlers'  balls 77 

Rollers  or  rolls  of  the  iron  works  80 

Angle  or  T  iron 81 

Varieties  of  iron 82 

CHAPTER  V. 

MANUFACTURE   OF    STEKL. 

Cementation 83 

Blistered  steel 84 

Shear  steel 84 

Cast-steel 84 

Characteristics    and  qualities  of 

steel 85 

Works  on  iron  and  steel 86 

CHAPTER  VI. 

FORGING    IRON  AND    STEEL. 

Management  of  fires 86 

The  blast 88 

Furnaces,  forges  and  hearths....  88 

Hand-forging 88 

Anchors 88 

Tongs  and  general  tools 90 

Oliver  or  small  lift-hammer 92 

Management  of  fires — the  degrees 

of  heat 94 

Ordinary  practice  of  forging 97 

Drawing  down,  jumping,  building 

up  or  welding 97 

Set-hammers,  flatters,  top-fullers.  98 

Twisting  the  work 98 

Practice  of  hammering 98 

i 


10 


CONTENTS. 


Anvils 101 

Methods  in  forging 101 

Making  bolts  and  nuts 103 

Mortises 105 

Levers,  arms,  brackets  and  frames  107 


CHAPTER  VII. 


ON    WROUGHT-IRON   IN   LARGE 

Forge  tools 

Limits  of  welding  power 

Auxiliary  tools 

Forge-hammers 

Nasmyth's  steam-hammer 

Effects  of  Nasmyth's  hammer 

Materials  for  forging 

Tendency  of  over-refined  iron  to 

deteriorate 115 

Cast  and  wrought-iron    for  ord- 
nance   116 

Tensile  strength  of  the  monster- 
gun 117 

Material  used  in  forging 119 

Varieties  of  treatment  required..  120 
Modes  of  working  large  forgings.  120 
Different  modes  of  forging  large 

iron  masses 121 

Forging  the  monster  gnn 122 

Crystallization  explained 123 

Crystalline  tendency  of  iron 125 

Causes  of  fissures  and  their  remedy  127 

Danger  of  forgings  in  cooling 128 

lleport  of  the  Franklin  Institute 

on  the  "  Princeton's"  gun 128 

Effects  of  hammer  hardening....   130 
Importance  of  metallurgy  to  en- 
gineers       1 

CHAPTER  VIII. 

GENKRAL  EXAMPLES   OF   WELDING. 

Shutting  together,  shutting  up....  131 

Welding  heavy  works 133 

The  butt  joint 133 

To  form  a  T  joint 133 

Conical  sockets,  wrought-iron 

hinges 134 

Musket-barrels 134 

Damascus-twist,  stub-twist  and 

wire-twist 135 

Wrought-iron  tubes 136 

Chains 136 

( )hain-cables 137 

Tires  of  wrought-iron  wheels  for 

locomotives «... 131 

Hatchets 138 

Spades 139 

Concluding  remarks  on  forging; 

and  the  applications  of  heading 

tools,  swage  tools,  punches,  etc.  140 


[leading  tools 140 

Swage  tools 141 

Trip  and  tilt-hammers,  manufac- 
tured at  the  Lowell  machine- 
shop 143 

CHAPTER  IX. 

HARDENING    AND    TEMPERING. 

General  view  of  the  subject 144 

Hammer  hardening '145 

The  quantity  of  carbon  in  cast- 
iron 145 

Steel  and  glass  polarized 146 

Practice  of  hardening  and  tem- 
pering steel 147 

Common  examples  of  hardening 

and  tempering  steel 153 

Razors,  penknives,  hatchets,  adzes, 

cold  chisels 154 

Saws  and  springs 155 

Less  common  examples  of  harden- 
ing and  precautionary  measures  158 

Jacob  Perkins's  discovery 158 

Oldham's  process 159 

CHAPTER  X. 

HARDENING   CAST   AND   WROUGHT-IRON. 

Chilled  iron  castings 163 

Malleable  iron  castings 164 

Case-hardening  wrought  and  cast- 
iron...  .  164 


CHAPTER  XI. 

ON   THE   APPLICATION   OF   IRON   TO   SHIP- 
BUILDING. 

Earliest  use  of  iron  in  canal-boat 

and  ship-building 167 

Variation  of  the  compass  in  iron- 
vessels  rectified 168 

Construction   of  iron  vessels   for 

ocean  traffic 169 

Half  cross  section  of  a  frigate. . .   170 

Ribs 170 

Keels 171 

Decks 171 

Form  of  the  deck-beams 171 

Riveting  of  the  plates 172 

Single   and    double    riveted   lap- 
joints 173 

Wood  and  iron  as  materials  for 

ship-building 175 

Resistance  to  tension  and  com- 
pression in  iron-ships 175 

Practical  tests  of  iron-ships 176 

Durability 178 

Economy 178 

Effects  of  shot  on  iron-ships 179 


CONTENTS. 


11 


CHAPTER  XII. 

THE    METALS    AND   ALLOYS    MOST    COM- 
MONLY USED. 

Description  of  the  physical  cha- 
racter and  uses  of  the  metals 
and  alloys  commonly  employed 
in  the  mechanical  and  useful 

arts 180 

Antimony , 180 

Bismuth 181 

Copper 181 

Alloys  of  copper  and  zinc  only...  183 
Remarks  on  the  alloys  of  copper 

and  zinc 184 

Alloys  of  copper  and  tin  only 185 

Remarks  on  the  alloys  of  copper 

and  tin  only 186 

Alloys  of  copper  and  lead  only. .   186 
Remarks  on  the  alloys  of  copper 

and  lead  only 187 

Alloys  of  copper,  zinc,  tin  and  lead  187 
Remarks  on  alloys  of  copper,  zinc, 

tin  and  lead 188 

Gold  alloys 190 

Nickel 195 

Palladium 195 

Platinum 196 

Rhodium 198 

Silver 198 

Silver  alloys 199 

Tin 200 

Zinc 201 

Babbitt's  anti-attrition  metal 203 

Teuton's  anti-friction  metal 203 

Alloy   of   the    standard  measure 

used  by  government 203 

Tutenage 203 

Expansion  metal 203 

Tables  of  the  cohesive  force  of 

solid  bodies 204 

Tabular  view  of  some  of  the  prop- 
erties of  metals 207 

Weights  of  wrought-iron,  steel, 
copper  and  brass  wire  and  plates  209 

CHAPTER  XIII. 

REMARKS    ON    THE    CHARACTER    OF    THE 
METALS    AND    ALLOYS. 

Hardness,  fracture  and  color  of 
alloys 210 

Malleability  and  ductility  of  alloys  212 
Strength  or  cohesion  of  alloys....   214 

Alloy-balance 214 

Table  for  converting  decimal  pro- 
portions into  divisions  of  the 

pound  avoirdupois 216 

Fusibility  of  alloys 217 

M.  Mallett's  process  for  the  pro- 
tection of  iron  from  oxidation..   217 
Falladiumizing  process '218 


CHAPTER  XIV. 

MELTING   AND    MIXTNQ   THE   METALS. 

The  various  furnaces,  etc.,  for 
melting  the  metals 220 

Antimony,  copper,  gold  and  silver 
and  their  alloys 221 

Observations  on  the  management  of 
the  furnace,  and  on  mixing  alloys  222 

Britannia  metal 224 

Barren's  furnace 229 

CHAPTER  XT. 

CASTING-  AND   FOUNDING. 

Metallic  moulds 230 

Earthen  moulds 230 

Complex  moulds ; . .  231 

Metal  moulds  for  pewter  works...  232 

Bearings  for  locomotive-engines.. .  233 

Type  founding.. .-. 235 

Plaster  of  Paris  moulds  and  sand 

moulds 236 

Stereotype  founding 237 

Moulding  sand  and  flasks 237 

Patterns,    moulds    and    moulded 

simple  objects 238 

Foundry  patterns 239 

Cores  of  moulds 241 

Moulding  cored  works 245 

Core-boxes 246 

False  core  and  drawback 248 

Reversing  and  figure-casting 249 

Casting  '   figures,      ornaments, 

branches  and  foliage 250 

Filling  the  moulds 252 

Gun  metal  and  pot  metal 253 

Iron-founders'  flasks  and  sand- 
moulds  254 

Remarks  on  patterns  for  iron- 
castings 261 

Loam  moulding 264 

Melting  and  pouring  iron 269 

New    method    of   manufacturing 

drop  shot 276 

CHAPTER  XVI. 

WORKS   IN    SHEET   METAL  XADE   BY  JOIN- 
ING. 

On  malleability,  etc.— division  of 

the  subject 278 

Terrestrial  globes 281 

Works  in  sieet  metal  made  by 
cuttiug,  bending  and  joining... .  281 

A  hexagonal  box 281 

Polygonal  figures  of  all  kinds 282 

Prismatic  vessels. 282 

Pyramids 282 

Frustums  of  pyramids -w- 


12 


CONTENTS. 


Mixed  polygonal  figures 283 

Radiating    pieces    for    polygonal 

vases 284 

Polygonal  vases  of  unequal  sides.  285 
Tools  for  working  in  sheet  met- 
als   286 

Modes  of  bending  curved  work...  288 
Improved  machine  for  rolling  up 

sheet-metal  pipe 291 

Angle  and  surface  joints 292 

Francis's  metallic  life-boats 295 


CHAPTER  XVII. 

WORKS  IN  SHEET  METAL,  MADE  BY  RAIS- 
ING ;  AND  THE  FLATTENING  OF  THIN 
PLATES  OF  METAL. 

Circular'  works  spun  in  the  lathe. .  300 

Works  raised  by  the  hammer 303 

Solid  and  hollow  blows 304 

Raising  and  hollowing. 306 

Raising  globes 307 

Vases 310 

Jelly  moulds 311 

Stamping 312 

Peculiarities    in    the    tools    and 

methods 313 

Principle  and  practice  of  flatten- 
ing thin  plates  of  metals  with 
the  hammer 316 

CHAPTER  XVIII. 

PROCESSES   DEPENDENT   ON   DUCTILITY. 

Drawing  wires,  etc 322 

Drawing  metal  tubes 327 

Hydraulic  press  and  arrangement 

for  manufacturing  lead -pipe 330 

CHAPTER  XIX. 

SOLDERING. 

General  remarks  and  tabular  view  332 
Tabular  view  of  the  process  of 

soldering 332 

Hard  soldering 333 

Soft  soldering 333 

Soldering  per  se,  or  burning  to- 
gether    334 

Alloys  and  their  melting  heats...  334 

Fluxes 334 

Modes  of  applying  heat 334 

Modes  of  applying  heat  dn  solder- 
ing   335 

The  use  of  the  blow-pipe . ! 337 

The  workshop  blow-pipe 338 

Examples  of  hard  soldering 339 

Examples  of  soft  soldering 341 

Richemont's  airo-hydrogen  blow- 
pipe   350 


CHAPTER  XX. 


Cutting  nippc 
Scissors  and 


SHEARS. 


shears  for  soft  flexi- 
ble materials 354 

Shears  for  metal  worked  by  man- 
ual power 360 

Engineers'  shearing  tools,  gener- 
ally worked  by  steam-power 364 

CHAPTER  XXI. 

PUNCHES. 

Punches  used  without  guides ....  370 
Punches  used  with  simple  guides.  374 
Punches  used  in  fly-presses,  and 
miscellaneous  examples  of  their 

products 377 

Punching  machinery  used  by  en- 
gineers.....'    388 

CHAPTER  XXII. 

DRILLS. 

Drills  for  metal,  used  by  hand 392 

O'Tool's  pin-drill 396 

Methods  of  working  drills  by  hand- 
power 397 

Drill  stocks 399 

Pump-drill 400 

Press-drill 400 

Expanding  braces  and  lever-drill.  403 

Ratchet-drill 403 

Differential  screw-drill 405 

Drilling  and  boring  machine 405 

Broaches  for  making  taper-holes..  413 

CHAPTER  XXIII. 

SCREW-CUTTING   TOOLS. 

Originating  screw 418 

Cutting  internal  screw  with  taps.  420 

The  principle  of  chamfering 423 

Transverse  sections  of  taps 423 

Die  stocks 428 

Master-taps 431 

Bolt-screwing  machine 437 

Shaping  machine 439 

Screws  cut  by  hand  in  a  common 

lathe 439 

Cutting  screws  in  lathes  with  tra- 
versing mandrels 440 

Cutting  screws  in  lathes  with  tra- 
versing tools 442 

Healey's    screw-cutting    appara- 
tus   445 

System  of  change-wheels  for  screw 

cutting 446 

Screw-tools  for  angular  threads...  453 
Screw-tools  for  square  threads 453 


CONTENTS. 


Various  modes  of  originating  and 

improving  screws 457 

Fusee  engine 459 

Ramsden's  screw-cutting  engine...  462 
Clement's  mode  of  originating  the 

sere w-guide 466 

Chucking  and  reaming  lathe 469 

Engine-lathe 470 

Screw-threads    considered   in  re- 
spect to  their  proportions,  forces 

and  general  characters 470 

The      measures      and      relative 

strengths  of  screws 472 

Sections  derived  from  the  angular 

thread 480 

Sections     derived     from    square 

threads 480 

Table  for  angular  thread-screws...  483 
Table  for  small  screws  of  fine  an- 
gular tl  reads 484 

Approximate  values  of  Holtzapf- 

fel's  original  screw-threads 485 

Holtzapffel's  original  taps 487 

CHAPTER  XXIY. 

HISTORY  OF  THE  ART   OF  ELECTRO-METAL- 
LURGY. 

Volta's  discovery 489 

Chemical  decompositions   by  the 

pile 490 

First  battery 490 

Decomposition  by  the  battery,  and 

its  application 490 

Deposition  of  metals  upon  others.  491 

Gilding 491 

Early  opinions  concerning  electro- 
decomposition 491 

How  these  results  affect  the  dis- 
covery   492 

Use  of  observed  facts 493 

Spencer's  first  experiments 493 

Jacobi's  experiments 493 

Jordan's  experiments 494 

Spencer's  first  printed  paper  upon 

electrotype 495 

Historical  anomaly 496 

Plumbago  as  a  coating 505 

Separate  battery 505 

Laws  of  deposition 506 

Works  published  on  electro-metal- 
lurgy   508 

Patents  taken  out  for  electro-met- 
allurgy    508 

CHAPTER  XXV. 

DESCRIPTION     OF     GALVANIC     BATTERIES, 
AND  THEIR  RESPECTIVE  PECULIARITIES. 

Nomenclature 509 

Proposed  terms 509 


Batteries f>10 

Single  pair  of  plates 510 

Best  kind  of  zinc 511 

Amalgamation      of      the      zinc 

plates 511 

Economy  in  amalgamation 512 

Distance    between    the    battery 

plates 513 

Different  elements  of  batteries....  513 
Properties  of  metals  fit  for  bat- 
teries   515 

Babington's  battery 517 

Wollaston's  battery 518 

Modification  of  Wollaston's  bat- 
tery now  in  use 518 

Defects  of  common  acid  batteries.  519 

Daniell's  battery 522 

Grove's  battery 524 

Bunsen's  battery 526 

Smee's  battery 527 

Earth  battery 529 

Magneto-electric  machine 530 


CHAPTER  XXVI. 

ELECTROTYPE   PROCESSES. 

Single-cell  operations 533 

Preparation  of  the  coin 534 

Forms  of  apparatus 535 

Comparative  view  of  exciting  solu- 
tions    536 

How  often    solutions    should  be 
changed,  and  zinc  amalgamated  537 

Making  of  moulds 538 

Preparation  of  wax 539 

To  take  moulds  in  wax 539 

Rosin  with  wax 539 

Moulds  in  plaster 539 

Moulds  in  fusible  alloy 540 

Moulds  in  gutta-percha 541 

Moulds  from  ferns,  sea-weeds,  etc.  541 

Nature  printing 542 

Casting  of  reptiles,  etc 54'J 

Wax  moulds  from  plaster 543 

Mould    of    plaster   from    plaster 

models 543 

Fusible  alloy  from  plaster 544 

Copper  moulds  from  plaster 544 

Elastic  moulding 544 

Moulding  of  figures 545 

Figures  covered  with  copper 545 

The  preparation   of  non-metallic 

moulds  to  receive  deposit 545 

Using  metal  moulds 547 

Precautions    on    putting   moulds 

into  a  solution 547 

Deposit  on  large  objects 547 

To  make  busts  and  figures 548 

Coating  of  flowers,  etc 548 

Figures  from  elastic  moulds 549 


CONTEXTS. 


Electrotypes  from  daguerreotypes.  550 

Depositing  by  separate  battery....  550 

Size  of  the  electrodes 552 

Relative  power  of  batteries 552 

Constancy  of  batteries 552 

Comparative  power  of  batteries..  553 
Recovery  of  mercury  from  waste 

zinc 556 

Compound  cell  process 556 

Effects  of  resistance 557 

Intensity 558 

Relative  intensity  of  batteries 559 

Mode  of  suspending  objects  in 

coating 560 

Non-trausfer  of  elements 561 

Effects  of  difference  in  the  density 

of  solutions 562 

Crystals  of  copper  on  electrodes..  562 

CHAPTER  XXVII. 

MISCELLANEOUS    APPLICATIONS     OF     THE 
PROCESS    OF    COATING    WITH    COPPER. 

Coppered  cloth 563 

Calico-printers'  rollers 564 

Etching  of  rollers 564 

Printing 564 

Glyphography 564 

Instruction  on  Glyphography  for 

the  amateur 566 

Copying  of  copper-plate  engrav- 

vings 568 

Coating  of  glass  and  porcelain 568 

On  galvanic  soldering 569 

Graham  plastic  niello 571 

CHAPTER  XXVIII. 

BRONZING. 

Brown  bronzes 573 

Another  method 573 

Black  bronzes 573 

Green  bronzes 574 

CHAPTER  XXIX. 

DEPOSITIONS    OF    METALS    UPON    ONE    AN- 
OTHER. 

Coating  of  iron  with  copper 574 

Cyanide  of  potassium 575 

Cyanide  of  copper 577 

Peculiarities  in  working  cyanide 

of  copper  solution 578 

Preparation  of  iron   for  coating 

with  copper 579 

Effects   of    conducting  power  in 

solutions  and  metals 579 

Illustration  of  conduction 580 

Nou-adherence  of  deposit 581 

Coating  cast-iron  with  other  met- 
als    581 


Coating  of  iron  with  zinc 583 

Sulphate  of  zinc 583 

Use  of  zinc  coating 584 

Influence  of  galvanism  in  protect- 
ing metals  from  destruction  by 
oxidation  and  solution 585 

CHAPTER  XXX. 

ELECTRO-PLATING. 

To  make  silver  solution 587 

Cyanide  of  silver  dissolved  in  yel- 
low prussiate  of  potash 588 

Solution  made  with  oxide  of  silver  588 
Solution   made  with    chloride  of 

silver 589 

The  best  method  of  making  silver 

solutions 589 

ulphite  of  silver  solution...  590 


Sulphite  of  silver-plating  solution  591 
To  recover  silver  from  solution....  592 
Preparation  of  articles  for  plating  593 
Practical  instructions  in  plating...  594 

Taking  silver  from  copper,  etc 597 

Cyanide  of  silver  and  potassium — 
decomposition  during  the  plat- 
ing process 597 

Other  effects  produced  in  working  598 
Machine  for  moving  goods 'while 
subjecting  to  the  electro-plating 

process 598 

Opposite   currents   of   electricity 

from  vats 600 

Tests  for  the  quantity  of  free  cya- 
nide of  potassium  in  solutions..  601 

Rate  of  depositing  silver 603 

Bright  deposit 603 

Different  metals  for  plating 603 

Electricity  given  off  from  sandy 

deposits 604 

The  old  method  of  plating 604 

Advantages  of  electro-plating 605 

Objections  to  electro-plating 606 

Solid  silver  articles  made  by  the 

battery 607 

Dead  silvering  for  medals 609 

Oxidizing  silver 609 

Protection  of  silver  surface 609 

Cleaning  of  silver 610 

CHAPTER  XXXI. 

ELECTRO-GILDING. 

Preparation  of  solution  of  gold...  610 
Battery  process  of  preparing  gold 

solution 611 

Process  of  gilding 612 

Conditions  required  in  gilding. . . .   612 

Maintaining  the  gold  solution 613 

To  regulate  the  color  of  the  gild- 
ing   614 


CONTENTS. 


15 


Coloring  of  gilding 614 

To  dissolve  gold  from  gilt  articles  614 

To  recover  the  gold 615 

Objections  to  electro-gilding 615 

Effects  of  cyanogen  on  health 615 

Practical  suggestions  in  gilding..  617 

Deposition  of  bronze 617 

CHAPTER  XXXII. 

RESULTS  OF  EXPERIMENTS  ON  THE  DEPOSI" 
TJPN  ON  OTHER  METALS  AS  COATINGS. 

Coating  with  platinum 617 

Coating  with  palladium 618 

Coating  with  nickel 618 

Antimony,  arsenic,  tin,  iron,  lead, 
bismuth  and  cadmium. 619 


Iron 619 

Lead 619 

Aluminium  and  silicium 619 

Tin 622 

Antimony 622 

Deposition  of  alloys 622 

CHAPTER  XXXIII. 

THEORETICAL   OBSERVATIONS. 

Action  of  sulphate  of  copper  on 

iron 628 

Faraday's  theory  of  electrolysis...  628 

Graham's  theory  of  electrolysis...  629 

Daniell's  and  Miller's  views 630 

Proposed  theory 631 

INDEX 633 


THE  PRACTICAL 

METAL-WORKER'S    ASSISTANT. 


CHAPTER  I. 

ON  METALLURGIC   CHEMISTRY. 

THE  USEFUL  METALS  AND  METALLIC  ORES  DEFINED. — Of  sixty  - 
four  simple  or  elementary  material  bodies,  no  less  than  fifty  or 
fifty-one  are  metallic.  We  shall  not  enter  upon  the  characteristics 
which  serve  to  define  a  metal — that  more  especially  belongs  to  the 
functions  of  a  chemical  treatise ;  but  taking  it  for  granted  that  the 
attributes  of  a  metal  are  sufficiently  well  agreed  upon  for  popular 
use,  we  shall  proceed  to  offer  a  few  general  remarks  on  their  useful 
properties,  of  which  rigidity,  cohesion,  tenacity,  and  durability  are 
the  most  remarkable,  although  many  more  are  conjoined  in  varia- 
ble degrees. 

The  ancients  were  only  acquainted  with  seven  metals,  whereas 
we  know  of  fifty  or  fifty-one;  nevertheless  those  now  in  most 
general  requisition,  and  to  which  the  appellation  "useful  metals'* 
most  peculiarly  belongs,  were  all  known  to  the  ancients.  Methods 
of  working  them,  however,  and  new  sources  from  which  to  obtain 
them,  have  multiplied  so  much  in  modern  times  as  almost  to  rank 
in  importance  with  the  discovery  of  the  existence  of  a  new  metal. 

Metals  are  either  found  native — that  is  to  say,  in  the  condition 
of  obvious  metallic  existence — or  they  are  combined  with  other 
substances,  so  as  to  lose  all  obvious  evidence  of  their  metallic  con- 
stitution. The  latter  condition  is  by  far  the  more  frequent;  and 
to  this  fact  more  than  any  other  the  consecutive  history  of  special 
metallic  discovery  is  attributable.  This  circumstance  leads  us  to 
an  important  chemical  consideration,  having  reference  to  the  com- 
parative tendencies  of  different  metals  to  combine  with  the  non- 
rnetallic  elements,  and  to  lose  by  such  combination  their  obvious 
metallic  form.  The  term  "noble  metals,"  though  applied  to  gold 
and  silver  in  ages  when  the  principles  of  chemical  science  were  un- 
known, has  nevertheless  a  positive  chemical  significance.  Modem 
discovery  has  added  platinum  to  the  list ;  and  thev  all  agree  in 
2  17 


18  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

the  property  of  being  very  slow  to  combine  with  any  foreign 
material  save  other  metals.  Hence  it  is  that  they  are  so  frequently 
found  (gold  and  platinum  almost  universally)  in  the  native  or 
metallic  state,  united  frequently  with  other  metals,  it  is  true,  but 
still  exhibiting  the  metallic  aspect.  If  the  noble  metals  existed  in 
larger  quantity,  offered  equal  facility  for  working  them,  and  equal 
hardness  after  being  worked,  their  slowness  to  unite  with  oxygen 
would  render  them,  more  than  all  others,  deserving  of  the  appella- 
tion of  "  useful  metals ;"  but,  being  deficient  in  these  qualities, 
notwithstanding  their  nobility,  they  must  yield  the  palm  to  iron, 
tin,  copper,  zinc,  and  lead,  in  the  first  instance,  and  perhaps  to 
mercury  or  quicksilver,  and  bismuth  also ;  considering  the  various 
applications  of  these  metals  to  the  useful  arts  of  life. 

The  progress  of  metallurgy  and  of  smelting  operations  demon- 
strates how  great  may  be  the  advance  of  arts  based  upon  scientific 
principles,  without  these  principles  being  understood.  The  pro- 
duction and  utilization  of  metals  are  intimately  allied  with 
chemistry ;  and  deriving  such  immense  advantages  from  the  appli- 
cation of  chemical  principles  at  this  time,  it  is  extraordinary  to 
reflect  on  the  comparative  excellence  to  which  the  art,  of  working 
several  useful  metals  had  arrived,  before  the  aggregation  of 
chemical  facts  and  principles  to  which  the  denomination  "  science" 
is  alone  justly  due,  had  dawned.  Chemical  science  may  be  indeed 
said  to  rest  on  an  historical  basis  of  metallurgic  aspirations,  and 
metallurgic  empiricism. 

Coeval  with  the  earliest  historical  records,  some  metals  were 
worked,  and  the  operations  of  working  involved  the  influence  of 
chemical  laws ;  yet  the  simplest  principles  of  chemistry  had  not 
then  dawned.  At  later  periods  it  was  alchemy — the  vague  hallu- 
cination of  making  gold — which  prompted  men  to  undertake 
investigations  fruitful  of  chemical  deductions,  to  be  marshalled 
into  a  science  hereafter.  Metallurgy,  then,  may  justly  lay  claim 
to  be  considered  the  fountain  source  of  chemistry ;  and  the  subse- 
quent development  of  the  science  to  the  art,  might  supply  the 
theme  of  argument  in  favor  of  empiricism  over  intellectualism,  if, 
at  various  periods  within  the  last  two  hundred  years,  the  miner 
and  the  metallurgist,  by  their  devotion  to  chemistry,  and  the 
chemist  by  his  successful  labors  in  the  practical  fields  of  mining 
and  smelting,  had  not  demonstrated  how  mutual  is  the  relation 
between  theory  and  practice,  how  inseparable  for  good,  how 
redundant  of  advantages  the  one  to  the  other.  Metallurgy  (accept- 
ing the  word  in  its  most  extensive  signification)  derives  its  best 
processes,  and  not  unfrequently  its  best  practical  aids,  from  a  due 
appreciation  of  chemical  principles.  And,  on  the  other  hand,  the 
mere  theoretical  chemist  derives  a  useful  lesson  of  the  necessity  of 
checking  his  theoretical  deductions  by  facts,  as  they  are  found  to 
be,  by  attending  to  some  of  the  teachings  of  metallurgy.  Several 
metallic  operations  there  are,  the  success  of  which  is  at  variance 
with  all  the  theoretical  indications  of  chemistry.  "Corpora  no  i 


OX   METALLURGY   CHEMISTRY.  19 

agunt  nisi  fluida"  was  a  chemical  dictum  of  received  universality ; 
nevertheless,  the  practice  of  annealing,  or  the  conversion  of  iron 
into  steel  by  combination  with  carbon,  is  a  practical  refutation  of 
the  universality.  This  process  consists  in  the  heating  together 
iron  bars  and  wood-charcoal  in  a  suitable  furnace.  Both  iron  and 
carbon  are  here  brought  together  in  the  solid  state ;  both  may  be 
said  to  be  devoid  of  volatility,  and  almost  of  liquidity ;  neverthe- 
less, in  violation  of  the  formerly  received  canon,  combination 
ensues,  and  steel  is  made.  A  similar  disaccordance  between  the 
indications  of  theory,  and  the  teachings  of  practice,  is  illustrated 
by  the  hot-blast  operation,  introduced  some  years  ago  in  the 
practice  of  iron  smelting.  On  the  other  hand,  chemistry  illumi- 
nates many  dark  recesses  in  the  field  of  metallic  empiricism,  and 
points  to  facts,  the  existence  of  which  would  not  have  been  sus- 
pected. 

It  is  unnecessary,  however,  further  to  expatiate  on  the  advan- 
tages which  the  metal-worker  derives  from  the  knowledge  and 
application  of  chemical  theory,  the  connection  being  now  admitted 
by  none  more  readily  than  by  the  practical  metallurgist. 

HISTORY  OF  METALLURGY. — In  illustration  of  the  mutual 
dependences  of  a  branch  of  practical  metallurgy  and  chemical 
science,  it  may  be  here  not  unadvisable  to  anticipate  the  contents 
of  the  monographs  which  especially  deal  with  special  metals,  and 
to  trace  cursorily  the  various  phases  which  the  production  of  the 
metal  iron  has  undergone.  From  one  of  several  metalliferous 
sources  this  useful  body  has  been  produced  from  perhaps  the 
earliest  historical  periods.  True  though  it  be  that  the  ancient 
Greeks,  at  the  very  earliest  period  of  their  history,  do  not  seem  to 
have  been  acquainted  with  the  existence  o£  far  less  the  method  of 
working,  iron — yet  we  read  of  both,  in^  Scripture ;  and  there  is 
good  reason  to  believe  that  anterior  to  the  earliest  historical  record 
of  the  Greeks,  iron,  and  the  processes  of  manufacturing  it,  were 
known  in  China  and  Hindostan.  We  know,  too,  that  immutability 
is  impressed  on  all  the  processes  of  the  East ;  whence  it  is  not  un- 
reasonable to  infer  that  the  processes  of  rude  iron  manufacture  now 
followed  in  Asia,  are  types  of,  if  not  identical  with  the  processes 
followed  there  in  times  long  passed.  What  are  these  processes  ? 
What  is  their  general  characteristic  ?  What  are  the  principles  in- 
volved ?  What  is  the  result  ?  One  general  scheme  of  appliances 
pervades  them  all.  The  object  is  to  begin  with  an  ore  of  iron 
capable  of  reduction  by  charcoal  fuel,  and  of  yielding  a  semi-fluid 
result,  which  the  subsequent  process  of  welding  fashions  into  shape. 
Even  in  this  simple  form  of  iron-smelting,  a  good  deal  of  latent 
chemistry  is  involved;  but  the  fullest  acquaintance  with  chemistry 
could  not  improve  the  practice  of  iron-smelting,  as  followed  by  the 
Persians  and  Hindoos,  if  limited  to  the  means  at  their  command, 
and  the  ends  proposed  to  be  gained.  The  iron  manufacture  of 
England,  as  prosecuted  in  bloomaries  by  the  aid  of  charcoal  fuel 
was  only  a  modification  of  the  Persian  meth j  1,  and  conducted 


20  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

almost  as  empirically.  No  sooner  was  the  practice  of  iron-smelt- 
ing by  charcoal  fuel  abolished,  and  pit-coal,  or  its  immediate 
derivative  coke,  introduced,  then  an  application  of  chemical 
principles  became  necessary.  How  far  these  applications  resulted 
in  empirical  tentative  experiments,  or  in  the  suggestions  of  chemi- 
cal teaching,  it  would  not  be  possible  at  this  time  to  decide ;  but 
the  historian  of  the  iron  manufacture  has  not  to  pursue  his  labors 
much  further  before  the  reaction  of  chemical  knowledge  on  mere 
empiricism  is  made  evident.  Practice  demonstrated  the  fact  that 
coal-smelted  iron  was  inferior  to  charcoal-smelted  iron;  but 
practice  could  not  say  wherefore,  until  science  came  to  the  iron- 
smelter's  aid,  making  known  to  him  the  composition  of  pit-coal, 
proving  that  it  contained  many  foreign  substances,  which  found 
their  way  into  the  smelted  iron,  and  injured  its  quality.  Analysis 
of  coal-smelted  iron  demonstrated  the  existence  of  both  sulphur 
and  phosphorus  incorporated  with  it,  demonstrated  moreover  that, 
costeris  paribus,  the  amount  of  deterioration  of  the  iron  was  in 
direct  proportion  to  the  quantity  of  these  elements  which  it  con- 
tained. 

Chemistry  next  began  to  shed  a  light  on  the  nature  and  property 
of  fluxes,  in  showing  how  a  mixture  of  several  iron  ores  might 
conduce  to  yield  a  more  fluid  mass  in  the  furnace  than  any  one  ore 
by  itself.  The  next  chemical  glimmering  fell  on  the  apprehension 
of  Cort,  that  Nestor  of  the  British  iron  trade,  and  led  to  his  im- 
provements in  the  processes  of  refining  and  puddling,  the  results 
of  which,  combined  with  the  rolling  aid  devised  by  his  mechanical 
genius,  eventuated  in  Britain,  supplying  iron  in  large  quantities 
to  other  countries,  from  which  she  had  heretofore  obtained  that 
metal. 

It  was  our  proposition^that  as  the  operations  of  metallurgy 
(accepting  the  word  in  ifs  largest  sense)  came  down  to  our  own 
times,  the  reaction  of  theoretical  chemistry  upon  its  practical 
development  has  continued  to  increase.  Whilst  the  supply  of 
British  wood-charcoal  lasted,  and  before  the  demand  for  iron 
became  so  enormous,  as  it  has  from  the  beginning  of  the  last 
century,  charcoal  answered  its  purpose  tolerably  well.  The  iron 
manufactured  by  it  resulted  in  small  quantity ;  but,  by  comparison 
with  coal,  or  coke-smelted  iron,  it  was  pure.  England,  however, 
in  course  of  time  became  deforested  in  the  neighborhood  of  the 
existing  iron-works,  the  source  of  wood-charcoal  thus  failed,  and 
pit-coal  of  necessity  was  obliged  to  be  employed  henceforth  for  the 
production  of  iron.  Simultaneously  with  its  adoption,  the"  clay 
iron-stone  began  to  supply  the  place,  to  a  variable  extent,  with 
iron  ore.  The  result  was  attended  with  both  advantages  and 
defects. 

Iron  admitted  of  being  obtained  in  enormous  quantities  from 
these  sources ;  but  it  had  no  longer  the  purity  of  the  charcoal-iron 
of  heretofore.  Not  only  was  the  quality  of  the  result  deteriorated 
by  the  presence  of  impurities  originally  contained  in  the  ore,  but 


ON    METALLURGY   CHEMISTRY.  21 

other  impurities,  especially  sulphur,  derived  their  existence  from 
the  coal  or  coke  employed  as  fuel.  Against  the  presence  of  these 
impurities,  iron  manufacturers  have  continued,  in  one  sense,  to 
struggle  up  to  the  present  time.  The  difficulty  of  getting  rid  of 
these  impurities,  however,  has  not  been  entirely  disadvantageous. 
The  fact  is  known  even  to  general  popularity,  that  the  only  differ- 
ence between  wrought-iron  and  cast-iron  consists  in  the  relation, 
between  the  extraneous  bodies — chemically  speaking,  impurities — 
in,  each,  and  the '  results  of  mechanical  action  upon  the  former. 
Iron  absolutely  or  chemically  pure,  is  far  more  rare,  and  more 
difficult  to  obtain  than  absolutely  pure  gold.  It  is,  indeed,  only 
met  with  in  chemical  laboratories,  and  very  seldom  there. 
Wrought-iron,  however,  may  be  practically  considered  as  pure 
iron ;  and  cast-iron  as  the  latter  combined  with  some  four  or  five 
per  cent,  of  impurities.  That  such  impurities  are  not  prejudicial 
to  the  nature  of  iron  for  all  purposes  and  all  uses,  will  be  rendered 
sufficiently  evident  by  a  consideration  of  the  products  made  of 
wrought  and  cast-iron  respectively.  Wrought-iron  (that  is  to  say, 
commercially  pure  iron)  is  almost  infusible.  By  virtue  of  its 
malleability  and  power  of  adhesion  under  the  operation  of  welding, 
it  may  be  fashioned  into  a  multiplicity  of  useful  forms;  but  if  any 
person  casts  his  eye  over  the  comparative  number  and  variety  of 
the  products  of  cast  and  wrought-iron  respectively,  and  reflects  on 
the  fusible  quality  which  the  presence  of  certain  impurities  confers, 
he  will  rise  from  the  survey  with  the  conviction  that  the  existence 
of  these  impurities  in  iron,  and  the  difficulties  of  evolving  them, 
are  not  without  their  advantages.  To  these  circumstances  we  owe 
the  enormous  development  which  the  production  and  working  into 
shape  of  cast-iron  has  attained ;  so  that  whilst  we  have  been  neces- 
sarily dependent  upon  the  purer  charcoal  iron  of  Sweden,  Norway, 
and  Russia,  as  the  basis  of  our  steel  and  wrought-iron  for  exclusive 
purposes,  cast-iron  girders  and  bridge-beams  made  in  this  country 
have  been  largely  exported. 

Nevertheless,  it  was  desirable  that  we  should  not  be  restricted 
to  the  operation  of  casting,  but  that  we  should  be  able  to  abstract 
the  four  or  five  per  cent,  of  impurities  from  the  cast  material,  and 
thus  change  it  into  wrought-iron.  All  the  consecutive  improve- 
ments in  refining  and  puddling  have  had  reference  to  this  end ; 
but,  notwithstanding  the  comparative  perfection  to  which  these  pro- 
cesses have  been  brought  by  Cort,  and  others — notwithstanding  the 
mechanical  aids  of  hammering  and  rolling,  by  which  it  was  hoped 
that  such  impurities  as  could  not  be  rendered  capable  of  entering 
by  combustion  into  volatile  products  would  be  mechanically 
forced  away — the  problem  has  never  been  solved  of  abstracting  the 
impurities  from  cast-iron,  and  rendering  the  result  equal  in  quality 
to  the  charcoal  wrought-irons  imported  from  Russia,  Norway,  and 
Sweden.  All  the  chemical  processes  of  iron  purification  hitherto 
employed  on  the  large  scale  had  been  based  on  the  operation  of 
bringing  highly -heated  external  surfaces  of  molten,  or  pasty  iron 


22  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

in  contact  with  atmospheric  air,  and  renewing  the  surface  as 
often  as  the  impurities  which  studded  it  had  been  burned  away. 
The  operations  of  refining  and  paddling  were  designed  with  this 
object  in  view ;  and  the  operations  of  mechanical  extrusion  effected 
by  hammering,  or  cylindrical  pressure,  were  designed  with  the 
object,  and  successfully  carried  out  up  to  a  certain  point,  of  accom- 
plishing by  mechanjcal  means  that  which  chemistry  alone  was 
unable  to  effect. 

KEFINING  PROCESSES. — Every  person  who  takes  a  passing 
glance  at  the  operations  of  metallurgy  in  the  aggregate,  cannot 
fail  to  be  struck  with  a  certain  functional  similarity  between  the 
process  of  cupellation  as  applied  to  separate  ignoble  from  noble 
metals,  and  the  process  of  puddling,  by  virtue  of  which  the  im- 
purities held  by  cast-iron  are  removed  from  the  latter.  In  both 
cases  the  general  result  is  obtained  by  passing  a  current  of  air 
over  a  highly-heated  metallic  surface.  The  puddling  process  (for 
perfecting  which  the  world  "was  indebted  to  the  ill-requited 
Kichard  Cort)  consists  in  placing  partly-purified  iron  in  a  rever- 
beratory  furnace,  and  vigorously  stirring  it  about  so  as  to  expose 
it  to  the  action  of  the  air :  by  which  operation  oxygen  is  rapidly 
absorbed,  while  carbonic  acid  gas  escapes,  giving  the  metal  a 
bubbling  and  boiling  appearance.  As  carbon  escapes,  the  metal 
passes  from  a  fluid  to  a  spongy  half-fluid  mass ;  and  in  this  state  it 
is  ready  for  the  puddler.  The  metal  is  collected  at  the  end  of 
an  iron  bar,  in  a  ball  or  bloom  of  sufficient  size,  which  is  swung 
through  the  air,  and  placed  under  the  forge-hammer,  to  the  crush- 
ing blows  of  which  it  is  subjected,  being  turned  and  twisted  in 
every  possible  direction,  while  sparks  of  fire  dart  from  the  surface, 
and  liquid  drops  exude  from  the  interior  of  the  metal.  #  4 

This  is  continued  until  the  ball  rings  under  the  hammer,  and 
the  liquid  drops  g*ve  place  to  scaly  masses.  In  this  state  it  is 
passed  through  the  rollers,  in  the  grooves  of  which  it  is  drawn  out 
and  compressed,  then  doubled  up  and  rolled  ;  again  heated,  doubled 
up  and  rolled,  until  the  process  is  complete.  The  new  process, 
by  which  the  reader  will  bs  at  no  loss  to  understand  that  we 
advert  to  the  scheme  devised  by  Mr.  Bessemer,  advances  by  one 
step  further,  as  it  is  stated,  and  may  be  considered  to  be  a  nearer 
approach  to  the  complete  purification.  By  it  a  current  of  atmos- 
pheric air  is  forcibly  projected  not  over  but  through  a  molten 
mass  of  impure  iron;  and  it  is  assumed  that  by  the  chemical 
operation  of  this  atmospheric  blast,  such  impurities  as  are  at 
once  combustible,  and  the  volatile  results  of  combustion,  will  be 
expelled. 

Now  the  combustible  extraneous  matters  are  for  the  most  part 
carbon,  sulphur,  and  phosphorus.  The  results  of  combustion  of 
the  first,  will  evidently  be  carbonic  acid  and  carbonic  oxide,  both 
volatile;  of  the  second,  sulphurous  acid,  also  volatile;  of  the  third, 
phosphoric  acid,  not  volatile.  The  theory  of  the  process  is  based 
upon  the  idea  of  removing  the  imourities  by  the  heat  developed 


ON   METALLURGIC   CHEMISTRY.  23 

from  their  own  combustion,  instead  of  employing  other  combusti- 
bles, themselves  holding  impurities. 

A  more  beautiful  and  more  immediate  application  of  chemical 
knowledge  to  improvement  of  the  iron  manufacture  it  is  impossible 
to  conceive ;  although-  from  its  recent  occurrence,  and  the  proba- 
tionary stage  to  which  it  has  only  yet  arrived,  we  are  precluded 
from  treating  of  it  without  a  certain  feeling  of  constraint  insepara- 
ble from  the  dawn  of  all  new  inventions. 

Pur  remarks  have  already  conveyed  sufficient  intimation  of  our 
cognizance  that  the  indications  of  theory  and  the  deductions  of 
practice  are  not  always  accordant  to  satisfy  the  reader  of  our 
ireadom  from  any  mere  theoretical  bias.  At  this  early  period, 
however,  Mr.  Bessemer,  in  common  with  every  inventor  who  lays 
before  the  world  a  proposition  which  he  believes  in,  and  which  a 
large  section  of  the  public  is  prepared  to  receive  as  an  improve- 
ment on  pre-existing  modes,  is  probably  experiencing  some  of  the 
crosses  and  disagreeables  inseparabfe  from  the  office  of  pioneer  in 
the  regions  of  science  or  the  arts.  It  is  only  a  matter  of  common 
justice,  then,  that  those  who  have  to  speak  or  write  of  processes  in 
his  domain,  should  give  them,  so  far  as  in  them  lies,  a  helping 
word  of  congratulation.  Without,  therefore,  committing  ourselves 
to  a  premature  expression  as  to  how  much  or  how  little  the  pro- 
cesses may  accomplish,  we  are  justified  in  stating  that  which  is 
much  more  satisfactory  to  him  and  to  us.  The  communications 
we  have  opened  in  relation  to  the  matters  in  hand,  have  necessarily 
thrown  us  into  correspondence  with  various  iron-smelters.  On 
the  premises  of  one  of  these — one  of  the  largest,  if  not  the  very 
largest  in  Great  Britain — Mr.  Bessemer's  process  is  about  to  be 
placed  on  trial,  and  under  the  most  favorable  auspices  for  a  search- 
ing and  impartial  one ;  the  result  of  which  will  be  communicated 
to  our  readers  in  the  present  volume. 

But  it  becomes  a  question  of  very  grave  import,  and  one 
requiring  the  test  of  wear  and  tear  of  time  as  well  as  experiment, 
to  set  at  rest,  whether  there  are  not  mechanical  requirements  in 
preparing  malleable  iron  not  comprised  in  Mr.  Bessemer's  pro- 
cess. Iron,  like  all  other  metals,  has  a  strong  tendency  to  crystallize 
at  a  given  temperature  ;  and  an  ingenious  friend,  theorizing  on  the 
subject,  suggests  an  hypothesis  which  we  have  not  met  with  before, 
that  the  puddling  process  supplies  a  mechanical  as  well  as  a 
chemical  bond  of  union  in  the  metal.  The  crystals,  he  suggests, 
are  disturbed  at  the  moment  of  formation,  driven  into  each  other 
by  the  stirring  operation ;  and  that  the  jagged  edges  of  the  particles 
thus  become  knitted  or  laced  into  each  other  in  a  fibrous  mass. 

This  would  seem  to  explain  the  tenacious  and  fibrous  character 
of  wrought-iron ;  and  if  so,  it  may  be  doubted  if  the  new  process 
will  altogether  supersede  that  of  puddling,  though  it  may  greatly 
facilitate  the  operation. 

Nor  does  it  appear  that  Mr.  Bessemer  will  be  suffered  to  mo- 
nopolize the  attention  of  those  interested  in  iron.  Mr.  Plant,  of 


24  THE   PRACTICAL    METAL- WORKER'S   ASSISTANT. 

Holly  Hall  Colliery,  Dudley,  had  patented,  as  early  as  July,  1849 
:\  refining  process  by  which  a  current  of  air  and  steam  is  directed 
upon  the  iron  while  it  is  in  the  puddling  furnace.  Another  pro- 
cess, patented  in  1855,  by  Mr.  Martien,  of  New  Jersey,  consists  in 
passing  currents  of  air  and  steam  through  the  heated  cast-iron  as  it 
runs  from  the  blast  furnace.  A  third  invention  is  by  Captain 
Uchatius,  Engineer-in- Chief  of  the  Imperial  Arsenal,  Vienna,  who 
has  devised  a  method  of  producing  every  description  of  cast-steel 
from  crude  pig-iron  in  the  short  space  of  three  hours ;  and  the 
process  was  exhibited  in  London  before  a  number  of  scientific  and 
practical  men,  to  their  entire  satisfaction,  as  it  is  stated  ;  although 
these  experiments  were  conducted  in  furnaces  not  well  suited  to 
the  operation.  This  process  consists  of  running  melted  pig-iron 
from  a  crucible  into  a  vessel  filled  with  water,  when  the  iron  is 
converted  into  small  granulated  shot-like  particles.  A  weight  of 
twenty-four  pounds  of  these  granulated  iron  drops  was  mixed  with 
crushed  ore  and  filled  into  a  crucible,  which  was  placed  on  the 
furnace  prepared  for  it.  After  the  lapse  of  a  period  of  two  hours 
and  three-quarters,  the  crucible  was  taken  from  the  furnace  and  the 
contents  poured  into  an  iron  mould.  .  When  this  was  opened,  an 
ingot  of  steel  weighing  twenty-five  pounds  was  exhibited  to  the 
company,  and  pronounced  by  competent  judges  to  bear  every  ex- 
ternal evidence  of  being  perfect  in  quality.  While  this  metal  was 
being  melted,  an  ingot  of  steel  prepared  by  this  process  at  the  steel 
works  of  Messrs.  Turton,  of  Sheffield,  was  subjected  to  the  steam 
hammer,  and  a  bar  of  steel  produced  from  the  ingot  which  was 
pronounced  to  be  of  excellent  quality  by  the  practical  men  present. 
It  is  impossible  to  over-estimate  the  importance  of  these  discoveries 
should  they  bear  the  test  of  experiment  on  a  suitable  scale. 

Between  theoretical  indication  and  practical  confirmation,  how- 
ever, there  is  a  bridge  to  be  passed,  which  frequently  breaks  down 
and  engulfs  the  inventor,  through  the  interposition  of  some  collat- 
eral obstacle.  It  may  be  that  the  processes  of  Mr.  Bessemer  and 
the  other  ingenious  men  named  are  in  this  category.  Davy  sug- 
gested the  protection  of  the  copper  bottoms  of  ships  by  the  attach- 
ment of  zinc  galvanic  preservers.  He  caused  the  suggestion  to 
be  practically  carried  out,  and  quoad  protection  it  succeeded.  But 
Davy  was  foiled,  and  his  process  was  rendered  inoperative  through 
the  interposition  of  a  collateral  circumstance  which  had  not  en- 
tered into  his  calculations.  The  copper  was  no  sooner  prevented 
from  undergoing  solution,  than  its  surface  became  harmless ;  sea- 
weeds and  sea-mollusks  stuck  to  it,  and  the  ship's  course  was  im- 
peded thereby.  It  may  be  somewhat  thus  with  the  inventions  to 
which  we  have  adverted, — some  collateral  issue  may  interfere  with 
the  practical  realization  of  the  inventor's  hopes  in  respect  of  "the 
invention.  It  is  always  well  to  bear  in  mind  these  probabilities, 
seeing  that  they  are  the  reflex  of  the  history  of  most  inventions. 
But  nevertheless  the  theory  on  which  Mr.  Bessemer's  operation  is 
based  is  so  simply  beautiful,  that  now,  at  this  early  stage  of  it,  be- 


ON   METALLURGIC   CHEMISTRY.  '    25 

fore  the  ultimate  practical  issues  of  it  are  known,  it  is  fitting  that 
Mr.  Bessemer  should  be  cheered  wiA  the  provisional  recognition 
which  a  clear  apprehension  of  principles,  and  a  seemingly  prac- 
tical way  of  giving  them  effect,  bespeak  as  justly  his  due.  In  the 
puny  microcosm  of  a  chemical  laboratory,  where  thousands  of 
little  appliances  can  be  invoked  to  gain  the  end  proposed  by  chem- 
ical analysis — it  is  possible,  nay,  it  is  probable,  that  a  chemist  may 
not  justly  interpret  the  data  which  small  operations  evolve,  into 
the.  less  numerous,  though  individually  larger,  conditions  of  the 
practical  man. 

ADVANTAGES  OF  CAST-!RON. — We  have  already  intimated  that 
the  presence  of  impurities  in  iron  as  rendered  by  our  smelting 
works,  and  the  difficulties  of  removing  them,  are  not  barren  of  all 
good  results ;  and  we  have  adverted  to  the  capabilities  of  cast-iron. 
Let  us  now  contemplate  thft  subject  of  iron  from  the  opposite  point 
of  view ;  let  us  assume  that  instead  of  the  facility  wherewith  the 
genius  of  our  smelting  operations  enables  us  to  turn  out  enormous 
quantities  of  iron,  cast  into  the  form  required,  the  genius  of  the 
process  had  been  in  the  direction  of  depriving  us  of  this  impure 
material,  but  rendering  us  iron  commercially  pure — that  is  to  say, 
in  the  state  of  wrought  iron.  What  difficulties  would  have  beset 
us  then !  The  operation  of  casting  no  longer  possible,  but  every 
piece  of  manufactured  iron  being  necessarily  manufactured  by  the 
laborious  operations  of  forging,  hammering,  and  welding, — not 
merely  would  the  price  of  iron  for  many  purposes  have  been  en- 
hanced, but  for  numerous  purposes  to  which  iron  is  now  applied 
it  could  not  have  been  used  at  all.  Contemplate  the  prices  of  cast- 
iron  which  constitute  the  blocks  of  which  South wark  Bridge  is 
built,  and  imagine  the  circumference  of  blocks  having  the  same 
form,  weight,  and  dimensions,  made  of  wrought  instead  of  cast- 
iron,  and  hammered  into  shape.  The  thing  would  have  been  utterly 
impossible.  It  would  be  impossible  even  now,  notwithstanding 
the  aid  of  the  ponderous  steam-hammer.  The  ease  with  which  a 
blacksmith  heats,  and  welds,  and  fashions  into  shape  the  half- 
molten  paste  of  glowing  wrought-iron  on  his  anvil,  would  convey 
but  feeble  indications  of  the  difficulties  which  beset  these  opera- 
tions when  conducted  on  a  large  scale.  It  is  difficult  to  pronounce, 
and  it  would  be  invidious  to  make  the  attempt  of  fixing,  the  ex- 
treme limits  or  size  of  which  a  piece  of  wrought-iron  admits  of 
being  forged.  Practical  effect  is  given  to  that  operation  to  the 
extent  of  forging  anchors,  shafts  and  beams,  for  the  largest  marine 
engines.  These  are  achievements  sufficiently  difficult,  and  until 
lately  critics  were  found — nay,  indeed,  they  are  to  be  found  still — 
who  confidently  assert  that  much  beyond  these  achievements  of 
wrought-iron  manufacture  the  operation  could  not  go.  Whether 
wrought-iron  ordnance  of  large  size  could  or  could  not  be  manu- 
factured, having  the  strength  necessary  to  ordnance  practice,  was 
a  moot-point.  Some  years  ago  the  experiment  was  tried  in  the 
United  States,  and  failed, — as  a  terrible  accident  from  the  bursting 


26  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

of  a  wrought-iron  piece  of  ordnance  painfully  testified.  Since 
then  Mr.  Nasmyth  repeated  the  experiment,  with  so  bad  a  result 
that  it  was  considered  by  himself  to  be  a  failure,  and  he  expressed 
himself  very  hopelessly  respecting  wrought-iron  heavy  ordnance. 
Nevertheless,  a  large  piece  has  been  made  by  an  enterprising  Liv- 
erpool firm,  and  presented  to  the  British  government.  It  is  now, 
whilst  these  remarks  are  written,  under  process  of  trial ;  and 
hitherto  it  has  stood  all  the  tests  deemed  necessary  with  complete 
satisfaction. 

The  result  of  the  manufacture  of  this  interesting  piece  of  ord- 
nance, and  the  trials  to  which  it  has  been  subjected,  demonstrate 
that  those  who  ex  catJiedra  predicted  so  confidently  that  wrought- 
iron  heavy  ordnance  could  not  be  made  (due  regard  being  had  to 
their  strength),  may  have  reason  to  alter  their  opinions.  Con- 
fessedly, however,  as  between  the  casting  of  iron  into  a  specific 
shape,  and  the  welding  and  hammering  of  iron  into  a  similar  shape, 
the  difference  is  enormous. 

In  addition  to  the  mechanical  difficulties  attendant  on  the  ma- 
nipulation of  wrought-iron — in  addition  to  the  difficulties  of  re- 
moving huge  masses  of  it  from  the  forge  to  the  anvil — the  difficulty, 
moreover,  of  welding  two  or  more  large  pieces  together  in  such  a 
manner  as  to  give  solidity  to  the  welded  joint — a  chemical  or 
molecular  tendency  of  wrought-iron  when  retained  at  a  glowing 
heat  in  large  masses  for  long  periods  together,  threatened  to  impose 
an  insuperable  barrier  to  the  manipulation  of  wrought-iron  in 
pieces  much  larger  than  anchors,  or  marine  steam-engine  axes. 

CRYSTALLIZING  TENDENCY  OF  WROUGHT-!RON  IN  LARGE 
MASSES. — It  was  found  by  Mr.  Nasmyth,  in  turning  out  his  mon- 
ster gun,  that  the  iron  had  ceased  to  be  fibrous,  and  had  assumed 
a  crystalline  texture  at  its  centre,  thus  losing  the  strength  and 
tenacity  which  the  fibrous  condition  would  have  given.  It  had 
been  fully  known  that  wrought-iron  under  some  peculiar  circum- 
stances is  prone  to  assume  this  condition.  The  axles  of  revolving 
carriage-wheels  have  been  known  to  assume  this  crystalline  state 
from  vibration,  after  the  lapse  of  time  and  long  usage,  although  they 
were  originally  fabricated  of  the  best  wrought-iron.  Iron  wire 
too,  which,  as  all  connected  with  metallurgy  know,  is  necessarily 
made  of  the  purest  iron,  occasionally  assumes  this  crystalline  state 
if  long  exposed  to  the  agency  of  chemical  forces ;  as,  for  instance, 
in  a  laboratory.  Various  hypotheses  have  been  propounded  to 
afford  a  rational  explanation  of  this  molecular  change  from  fibrous 
to  crystalline  condition.  As  regards  the  case  of  railway  axles,  the 
supposition  appears  rational  that  constant  percussion  has  given  rise 
to  the  crystallized  state ;  but  the  change  experienced  by  iron  wire 
is  not  so  plausibly  explicable.  The  crystallization  of  large  masses 
of  wrought-iron  under  the  heating  and  cooling  process  involved 
in  the  operation  of  welding,  seems  to  admit  of  easier  explanation. 
The  result  appears  to  be  only  a  special  illustration  of  a  general 
resultant  of  the  undisturbed  play  of  cohesive  affinity,  tending  as 


ON    METALLURGY   CHEMISTRY.  27 

it  does,  if  sufficient  time  and  freedom  of  molecular  motion  be  given, 
to  assume  the  most  perfect  cohesive  state  of  which  matter  is  capa- 
ble— that  is  to  say,  the  state  of  crystals.  Had  the  result  of  crys- 
tallization been  inseparable  from  the  practice  of  welding  large  bars 
of  iron,  there  would  have  been  an  end  to  wrought-iron  ordnance 
of  large  calibre ;  there  would  have  been  an  end  also  to  the  pro- 
duction of  any  pieces  of  wrought-iron  considerably  larger  in 
dimensions  than  the  forms  hitherto  produced.  "We  shall  look 
forward  therefore  with  some  interest  to  the  monograph  on  the 
working  of  wrought-iron  in  large  masses  promised  us  by  Mr. 
Clay. 

Impressed  with  specialities  as  the  metals  are,  each  one  conducing 
to  certain  purposes  better  than  any  other — nevertheless,  with  the 
exception  of  iron,  these  capabilities  are  numerous,  and  one  gen- 
erally admits  of  being  substituted  for  another.  But  no  civilized 
race  could  exist  as  such  without  the  co-operation  of  the  metal  iron. 
For  the  greater  number  of  purposes  to  which  it  is  applied  there  is 
no  efficient  substitute.  True,  the  ancients  did  manage  at  one  time 
to  manufacture  cutting  instruments  out  of  bronze ;  true,  that  Sir 
Francis  Chantrey  in  our  own  times,  in  his  reverence  for  classic 
metallurgy,  caused  a  bronze  razor  to  be  made,  wherewith  he 
shaved ;  nevertheless,  we  doubt  whether  any  one  less  ardent  in  the 
love  of  ancient  metallurgy  than  himself  would  have  borne  con- 
tentedly the  daily  infliction. 

CLASSIFICATION  OF  METALS. — Before  indicating  the  chemical 
principles  upon  which  each  special  process  of  metallurgy  is  based, 
it  will  be  desirable  to  arrange  the  metals  in  classes,  according  to 
the  several  characteristics  which  they  present.  Great  specific 
gravity  is  so  prominent  a  characteristic  of  metallic  bodies,  viewed 
in  the  aggregate,  that  anterior  to  the  discovery  of  potassium,  so- 
dium, and  the  other  alkaline  and  terrigenous  metals,  the  quality 
was  thought  to  be  inseparable  from  the  metallic  condition.  So  far, 
however,  is  this  from  the  truth,  that  lithium — the  metal  of  the 
alkali  or  alkaline  earth  lithia :  it  may  be  said  to  be  intermediate 
between  the  two — is  the  lightest  known  solid,  metallic  or  non- 
metallic,  in  all  nature.  Based  on  a  consideration  of  the  quality  of 
specific  gravity,  then,  we  arrive  at  a  division  of  metallic  bodies 
into  the  light  and  the  heavy.  In  a  purely  chemical  sense,  such  a 
division  has  no  value.  But  it  is  otherwise  to  the  metallurgist. 
Inasmuch  as  the  metals  of  the  alkalies  and  alkaline  earths — that  is 
to  say,  the  light  metals — are  only  produced  by  complex  and  re- 
fined chemical  processes,  they  may  be  considered  as  lying  without 
the  domains  of  metallurgy.  It  is  only  with  the  remaining  class 
(the  heavy  metals),  therefore,  that  the  metallurgist  has  to  concern 
himself,  and  to  which  the  reader's  attention  throughout  this  intro- 
duction and  the  succeeding  pages  will  be  exclusively  directed. 
Contemplating  the  heavy  metallic  bodies,  in  a  practical  or  metal- 
lurgic  sense,  with  reference  to  their  subdivision,  their  various 
demeanor  with  regard  to  oxygen,  and  their  general  relations  to 


28  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

that  extensively  diffused  non-metallic  element,  we  have  a  natural 
as  well  as  a  ready  means  of  classification.  It  has  been  calculated 
that  almost  two -thirds  by  weight  of  our  globe's  constituents — 
solid,  liquid,  and  gaseous ;  its  vegetables,  and  its  animals  and  min- 
erals— consist  of  oxygen.  The  chemist  need  not  to  be  reminded 
of  the  powerful  tendency  to  combustion  which  oxygen  manifests, 
especially  with  metals.  Unquestionably  the  most  considerable 
and  the  most  important  metallic  ores  are  oxides,  or  combinations 
with  oxygen.  It  is  natural,  therefore,  that  the  metallurgist  should 
seek,  in  an  examination  of  the  relations  of  metals  to  oxygen,  the 
basis  of  their  practical  subdivision.  Five  well-marked  subdi- 
visions, founded  on  these  peculiarities,  admit  of  being  established. 
They  are  as  follow : 

1.  Metals  having  a  strong  tendency  to  combine  with  oxygen,  and 
to  generate  bases.     These  metals  admit  of  arrangement  in  three 
sections. 

§  (a).  Metals  whose  oxygen-compounds  are  basic,  or  have  the 
property  of  bases.  They  are  zinc,  cadmium,  lead,  and  uranium. 

§  (6).  This  section  has  only  one  representative,  i.  e.  arsenic,  or 
arsenicum ;  a  metal  the  peculiarity  of  which  is,  that  its  combina- 
tions with  oxygen  are  acid,  not  basic. 

§  (c).  Metals  which  form  both  acids  and  bases  by  combination 
with  oxygen.  They  comprehend  copper,  nickel,  cobalt,  bismuth, 
tin,  copper,  manganese,  iron,  antimony. 

2.  Metals  the  tendency  of  which  to  combine  with  oxygen  is  but 
slight :  comprehending  gold,  silver,  platinum,  and  mercury.     The 
three  former  are  sometimes  called  "  noble  metals." 

The  relative  fusibility  of  metals  also  affords  a  good  means  of 
practical  classification.  Having  reference  to  this  difference,  five 
well-marked  subdivisions  admit  of  being  established. 

1.  Fusible,  and  remaining  liquid  at  the  lowest  heat  of  temperate 
climes.     There  is  only  one  metal  which  answers  to  these  con- 
ditions :  it  is  mercury. 

2.  Fusible  between  392°  and  788°  F.,  and  passing  off  into  vapor 
when  the  heat  is  still  further  raised.     The  metals  represented  by 
this  subdivision  are  zinc,  cadmium,  lead,  bismuth,  antimony,  and 
arsenic  or  arsenicum. 

8.  Fusible  at  temperatures  above  1830°  F. :  copper,  silver,  gold. 

4.  Not  completely  fusible  by  the  strongest  furnace-heat :  man- 
ganese, iron,  nickel,  cobalt,  platinum. 

5.  Fusible  in  the  hydro-oxygen  jet :  chromium. 

ALLOYS. — Having  taken  a  cursory  survey  of  the  classes  and 
subdivisions  of  which  metals,  practically  considered,  are  suscep- 
tible, we  shall  now  proceed  to  describe  the  principal  compound 
forms  of  which  metals  are  susceptible.  The  first  of  these  which 
presents  itself  is  the  class  of  alloys. 

The  term  alloy  in  its  most  general  acceptation  means  the  mutual 
combination  of  two  or  more  metals.  When  one  of  the  metals, 
however,  entering  into  combination  is  mercury,  the  result  is  not 


ON   METALLURGIC   CHEMISTRY.  29 

usually  termed  an  alloy,  but  an  amalgam.  Alloys  are  practically 
interesting  to  the  metallurgist  in  two  ways ;  either  the  metals  to 
which  a  metallurgic  process  of  extraction  is  applied  are  found  in 
the  condition  of  native  alloy — i.  e.  one  naturally  existing — or  an 
alloy  results  as  the  consequence  of  an  intermediate  metallurgic 
process.  The  native  state  of  gold  with  silver,  and  of  platinum  with 
rhodium,  iridium,  palladium,  and  its  other  associated  metals,  pre- 
sent familiar  instances  of  native  alloys.  The  intermediate  com- 
binatkm  of  lead  and  silver  resulting  from  the  metallurgic  process 
of  reducing  galena,  furnishes  a  good  instance  of  the  second.  At 
the  present  time  the  belief  prevails — we  may  even  say  it  is  uni- 
versal— that  alloys  are  not  always  mere  mechanical  mixtures  of 
different  metals,  but  are  constituted  in  accordance  with  the  laws 
of  definite  chemical  combination ;  being  no  less  atomic  (to  adopt 
the  language  of  the  atomic  theory)  than  oxides  and  salts  are 
atomic.  It  would  lead  us  too  far  from  the  subject  of  metallurgy 
to  adduce  the  various  arguments  which  exist  in  favor  of  the  belief; 
and  indeed  a  superficial  glance  at  the  bearing  of  the  hypothesis 
would  perhaps  induce  the  practical  metallurgist  to  pass  it  by  as 
devoid  of  utilitarian  interest.  Few  subjects,  however,  are  more 
intimately  related  to  the  utilization  of  metals  than  those  involved 
in  the  seemingly  abstract  question  of  chemical  composition,  or  of 
mere  admixture,  in  relation  to  alloys.  An  illustration  very  much 
to  the  point  is  afforded  by  the  manufacture  of  the  alloy  called 
"  silver-steel." 

In  the  course  of  some  experiments  performed  by  Professor 
Faraday  and  Mr.  Stodart,  they  discovered  that  silver  when  fused 
with  steel  in  certain  given  proportions,  entered  into  mutual  com- 
bination, and  formed  a  valuable  alloy.  If,  however,  the  quantity 
of  silver  was  increased  above  a  certain  proportion  not  yet  quite 
ascertained,  the  excess  of  silver  was  extruded  from  the  metallic 
mass  during  the  process  of  cooling.  This  result  at  once  affords 
testimony  as  to  the  chemical  constitution  of  the  alloy,  and  points 
to  the  practical  advantages  likely  to  be  derived  from  a  solution  of 
the  question,  "What  are  the  exact  or  atomic  proportions  in  which 
steel  and  silver  can  combine  ?"  Granting,  for  the  sake  of  argu- 
ment, that  the  silver-steel  be  so  far  superior  to  ordinary  steel  as  to 
warrant  its  manufacture,  the  conclusion  follows  that  it  is  a  point 
of  the  utmost  importance  to  determine  the  exact  maximum  amount 
of  silver  which  steel  can  take  up.  Not  merely  would  the  addition 
of  every  grain  of  silver  beyond  the  indicated  proportion  be  an 
unnecessary  expense,  but  such  of  the  uncombined  silver  as  might 
be  locked  up  mechanically  in  the  alloy  during  the  cooling  process 
would  lessen  its  strength,  and,  indeed,  impart  a  general  deteriora- 
tion- of  quality. 

As  a  general  rule,  it  may  be  stated  that  all  metals  which  form 
alkalies  have  a  particular  tendency  to  unite  with  those  which  form 
acids.  When  two  metals  are  alike  in  their  affinities  for  oxygen, 
they  do  not  readily  combine,  and  may  often  be  separated  by  orys 


30  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

tallization  only,  when  both  metals  absorb  nearly  the  same  quan- 
tity of  oxygen  in  forming  their  oxydes.  Nearly  all  chemical 
combinations  liberate  heat.  Zinc  and  copper,  when  melted  to- 
gether, produce  a  high  temperature.  Where  a  mere  mechanical 
mixture  of  metals  occurs  in  an  alloy,  it  is  characterized  by  dis- 
tinct crystals  being  formed  with  one  metal,  between  which  the 
other  is  visible.  When  an  alloy  is  formed  with  proper  equiva- 
lents, no  such  disconnected  crystals  are  observed.  In  cooling  a 
melted  alloy,  that  composition  which  is  most  refractory  crystal- 
lizes first,  and  that  which  is  most  easily  reduced  to  fluidity  is  com- 
pelled to  occupy  the  spaces  between  the  cr}rstals.  Thus  copper 
and  tin  are  fusible ;  but  in  cooling,  copper-tin  crystallizes  first,  and 
tin-copper  last.  Iron  and  arsenic  are  very  fusible ;  but  in  cooling, 
iron-arsenic  crystallizes  first;  in  consequence,  the  surface,  when 
cool,  exhibits  a  perfect  net- work  of  bright  lines  in  regular  forms. 
In  all  of  these  compounds,  however,  portions  of  each  alloy  are 
contained.  When  a  bar  of  cold  lead  is  dipped  in  mercury,  the 
pores  of  the  lead  become  filled  with  mercury,  but  the  mercury 
also  absorbs  lead.  When  iron  is  strongly  heated  while  imbedded 
in  carbon,  as  is  the  case  when  blistered  steel  is  produced,  the  car- 
bon penetrates  to  the  very  centre  of  the  iron  rods ;  but  no  iron  is 
imparted  to  the  carbon,  because  its  atoms  are  not  movable. 

Alloys  are  more  fusible  than  the  individual  metals,  and  will  melt 
at  a  lower  temperature  than  the  mean  would  indicate.  Though 
tin  melts  at  500°,  and  pure  copper  at  2,500°,  equal  parts  of  copper 
arid  tin  do  not  melt  at  the  mean  1,500°,  but  at  a  lower  heat.  Pure 
iron  is  extremely  refractory ;  but  when  combined  with  arsenic  and 
phosphorus,  it  may  be  melted  in  a  cast-iron  pot  without  adhering 
to  it.  Again,  a  composition  of  three  metals  is  still  more  fusible 
than  their  various  degrees  of  melting  would  indicate ;  and  if  their 
component  parts  are  according  to  the  laws  of  chemical  affinity,  the 
melting  point  is  lower  still.  Need  we  repeat,  after  this,  how  im- 
portant is  the  study  of  forming  alloys  in  the  smelting-furnaces  ? 
It  is  the  degree  of  fusibility  of  the  slags  and  metals,  which  deter- 
mines the  cost  of  the  process. 

Iron  is  rendered  fusible  by  the  presence  of  carbon ;  but  when 
that  substance  is  removed  it  becomes  refractory,  and  can  hardly  bo 
melted.  Tin  is  refined  by  oxidizing  or  evaporating  sulphur, 
arsenic,  and  other  matters;  a  process  which  renders  tin  less  fusible 
and  more  tenacious.  Zinc  melted  in  an  iron  pot,  and  exposed  to 
the  air,  exhibits  dross  on  the  surface ;  its  fluidity  is  diminished, 
but  its  malleability  is  increased.  A  layer  of  carbon,  or  common 
salt  above  ashes,  prevents  these  phenomena. 

Alloys  are  generally  harder  than  might  be  expected  from  their 
constituents;  although  there  are  exceptions  to  the  rule.  Silver 
and  arsenic  render  iron  hard,  although  both  metals  are  soft  in 
themselves ;  copper  and  tin,  both  soft'metals,  become  hard  when 
melted  together  in  certain  proportions;  and  zinc  and  copper  makes 


ON   METALLURGY   CHEMISTRY.  31 

brass  soft.  Antimony  causes  all  metals  to  become  hard,  but  very 
brittle.  Iron  mixed  with  a  little  antimony  will  cut  glass. 

The  ductility  of  alloys  is  sometimes  greater  than  might  be  ex- 
pected ;  in  others,  it  is  more  brittle  than  the  original  metals.  Al- 
loys of  zinc  and  lead,  are  very  tenacious ;  lead  and  antimony,  very 
brittle.  Any  alloy  which  is  slowly  heated  and  gradually  cooled — • 
annealed,  that  is — is  softer  than  when  the  compound  is  suddenly 
chilled ;  hence  the  hardness  of  chill-cast  iron. 

The  above-mentioned  examples  are  types  of  many  others,  de- 
monstrating that  though  metallic  alloys  occupy  a  less  prominent 
position  than  metallic  oxides,  sulphurets,  chlorides,  etc.,  neverthe- 
less the  conditions  which  regulate  their  existence  must  not  be 
neglected  by  the  metallurgist. 

The  separation  of  the  constituents  of  metallic  alloys  is  accom- 
plished by  several  methods.  Of  these  the  one  most  obviously 
suggested  by  theory  consists  in  a  gradual  application  of  heat  up 
to  the  point  of  melting  the  more  fusible  metal,  and  leaving  the 
other  unfused.  In  this  way  lead  is  separated  from  an  alloy  of  that 
metal  with  copper.  Scarcely  less  obviously  suggested  by  theory 
is  the  application  of  heat  to  effect  the  volatilization  of  one  of  the 
metals  entering  into  an  alloy.  In  this  way  is  mercury  separated 
in  practice  from  alloys  (amalgams)  of  mercury  with  gold,  and  mer- 
cury with  silver.  In  this  way  also  is  silver  obtained  from  argen- 
tife^rous  zinc. 

The  metallic  constituents  of  some  alloys  admit  of  separation  by 
subjecting  them  to  fusion  and  gradual  cooling.  During  the  cool- 
ing process  the  metals  of  an  alloy  will  in  some  cases  separate  in 
layers  according  to  their  specific  gravity.  In  other  cases  the  sepa- 
ration ensues  from  one  of  the  constituents  shooting  into  crystals 
and  becoming  solid,  thus  furnishing  a  means  of  its  removal.  The 
celebrated  process  of  effecting  the  separation  of  silver  from  lead, 
known  as  Pattinson's  crystallization  process,  is  of  this  kind ;  but 
the  most  extraordinary  circumstance  in  relation  to  it  is,  that  the 
lead  or  the  metal  of  lesser  fusibility  is  that  which  first  crystallizes 
out.  The  rationale  of  this  curious  phenomenon  has  never  been 
explained.  Occasionally  separation  of  two  or  more  metals  consti- 
tuting an  alloy  is  effected  by  means  of  acid-solution.  The  process 
of  quartation  by  which  silver  is  dissolved  out  from  an  alloy  of 
that  rnetal  and  gold,  will  serve  as  a  familiar  illustration. 

METALLIC  OXIDES. — We  have  already  said  that  these  are  the 
most  numerous  and  the  most  important  of  metallic  ores.  The 
smelting  of  them  depends  on  an  application  of  the  best  prac- 
tical means  of  removing  oxygen.  The  relations  of  metals  to 
oxygen,  and  the  relative  facility  wherewith  they  evolve  oxygen 
wholly  or  partially,  have  all  been  accurately  determined  by  the 
chemist.  On  the  large  scale,  the  exact  agents  employed  in  the 
laboratory  for  effecting  <leo\i<l;ition  cannot  always  be  applied; 
nevertheless,  chemical  principles  have  to  be  followed  as  closely  as 
circumstances  will  permit:  therefore  it  will  now  be  proper  to  ex- 


32  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

plain  the  relations  of  different  metals  to  oxygen  in  respect  of  the 
comparative  difficulty  of  removing  that  element  from  them. 

The  reduction  of  metallic  oxides  may  be  effected  by  the  dry  and 
the  moist  processes.  It  is  the  former,  however,  which  immediately 
concerns  the  metallurgist,  and  to  which  we  purpose  to  direct  the 
attention  of  the  reader.  The  noble  metals  gold,  silver,  and  plati- 
num are  characterized,  as  is  well  known,  by  the  difficulty  where- 
with their  respective  combination  with  oxygen  admits  of  being 
effected.  Conversely,  the  respective  oxides  of  these  metals  are 
characterized  by  facility  of  decomposition.  The  application  of 
heat  alone,  without  the  contact  of  any  extraneous  body,  suffices  to 
liberate  oxygen  from  the  oxide  of  the  noble  metals,  and  of  course 
to  evolve  the  metal. 

All  other  metallic  oxides  require  the  agency  of  a  second  body 
to  effect  their  reduction,  mere  application  of  heat  being  insufficient ; 
and  a  consideration  of  the  deoxidizing  materials  at  the  disposal 
of  the  metallurgist,  and  employed  by  him,  opens  a  field  of  great 
utility  and  interest.  The  deoxidizing  agent  of  greatest  importance 
to  the  metallurgist  is  coal  in  its  several  varieties,  and  the  deriva- 
tive materials  yielded  by  its  combustion.  When  coal  is  burned 
in  a  furnace,  the  first  product  of  combustion  may  be  considered  to 
be  carbonic  acid  gas ;  but  inasmuch  as  the  latter  is  readily  decom- 
posed by  permeating  ignited  pieces  of  solid  carbon  (coke),  losing 
a  portion  of  its  oxygen,  and  becoming  carbonic  acid  gas, — we  may 
say  that  the  products  of  the  combustion  of  coal  are  firstly  carbonic 
acid ;  secondly,  carbonic  oxide  and  carbonic  acid ;  and  lastly,  car- 
bonic oxide  alone.  The  latter  in  combination  with  heat  is  a  most 
powerful  deoxidizing  agent.  Were  it  not  for  the  production  in 
furnaces  of  carbonic  oxide  gas — were  it  necessary  that  the  solid 
carbon  of  the  coke  should  be  alone  the  deoxidizing  body,  then  it 
follows  that  every  particle  of  the  ore  to  be  reduced  must  be 
brought  into  intimate  contact  with  the  reducing  body ;  a  process 
involving  more  care  and  trouble  than  are  compatible  with  large 
met'allttrgic  operations.  The  reducing  agent  being  a  gas,  there  is 
no  longer  a  necessity  for  that  intimate  mixture  of  fuel  and  ore 
which  would  otherwise  be  necessary.  Provided  that  the  gaseous 
results  of  combustion  are  placed  under  circumstances  of  readily 
permeating  the  ore,  the  necessities  of  practice  are  amply  subserved. 
In  many  cases  of  reduction  of  the  oxides  of  lead,  silver,  tin,  and 
copper,  the  fuel  is  actually  contained  in  a  furnace  by  itself,  the  ore 
to  be  reduced  being  in  another.  There  is  great  difference  as  to 
the  amount  of  heat  at  which  the  reduction  of  different  metallic 
oxides  can  be  effected.  The  oxides  of  lead,  bismuth,  antimony, 
nickel,  cobalt,  copper,  and  iron,  require  a  strong  red  heat;  whilst 
the  oxides  of  manganese,  chromium,  tin  and  zinc,  do  not  lose  their 
oxygen  until  heated  to  whiteness. 

Combinations  of  the  metallic  ores  with  oxygen  take  place  in 
certain  definite  proportions,  and,  so  far  as  relates  to  most  metals, 
in  definite  quantities.  There  are  three  oxides  of  iron  which  in- 


ON    METALLURGIC    CHEMISTRY.  33 

terest  us  here,  namely — the  protoxide  of  iron,  which  is  a  strong 
base ;  the  magnetic  oxide,  a  feeble  base ;  and  the  peroxide,  which 
is  more  of  an  acid  than  a  base.  Peroxide  and  protoxide  of  iron, 
both  infusible  by  themselves,  form  a  fusible  slag.  Arsenic  forms, 
in  all  states  of  oxidation,  an  acid  which  never  melts  with  any  other 
acid,  or  with  highly  oxidized  metals  ;  it  being  a  requisite  condition 
of  fusibility,  that  one  of  the  constituents  in  which  the  other  is 
merely  suspended  must  be  fusible.  This  chemical  relation  admits 
of  a, wide  range,  nor  is  the  same  substance  in  all  its  relations  of 
the  same  character. 

The  oxides  of  iron  are  always  basic  as  to  silic  acid,  but  they  are 
acid  in  relation  to  oxide  of  lead.  The  study  of  the  metallurgist 
must  be  directed  to  these  chemical  relations,  as  well  as  to  the  de- 
gree of  fusibility  of  the  compounds  and  the  relation  they  bear  to 
the  metal  to  be  produced  under  their  influence. 

As  a  rule,  it  may  be  stated  that  the  compounds  of  single  equiva- 
lents of  metal  and  oxygen  constitute  a  base  of  alkali,  and  that- the 
addition  of  more  oxygen  destroys  that  property.  Thus  the  pro- 
toxide of  manganese  is  a  strong  base,  and  precipitates  the  protox- 
ide of  iron  from  a  slag ;  but  the  peroxide  of  manganese  is  driven 
out  by  the  protoxide  of  iron.  When  carbon  is  present,  one  atom 
of  oxygen  is  absorbed  by  it  from  the  peroxide  of  manganese,  and 
the  iron  is  again  driven  from  its  union.  This  affinity  of  oxygen 
for  metal  is  most  difficult  to  be  overcome  at  a  state  of  oxidation 
half-way  between  the  extremes.  Protoxide  of  tin  is  easily  con- 
verted into  metal,  so  is  peroxide ;  but  the  sesquioxide,  interme- 
diate between  the  two,  presents  much  greater  difficulties.  Prac- 
tically it  is  usual  to  smelt  with  the  highest  oxides,  and  convert 
the  ores  into  that  state,  in  order,  not  only  to  remove  the  oxygen 
from  the  metal,  but  also  to  produce  so  high  a  heat  as  to  fuse  the 
metal  at  the  precise  moment  when  the  oxygen  is  removed. 

Hydrogen  and  carburetted  hydrogen  gases  must  not  be  omitted 
in  our  enumeration  of  the  deoxidizing  agents  employed  by  the 
metallurgist.  The  latter  agent,  carburetted  hydrogen,  is  evolved 
during  the  combustion  of  coal ;  the  former,  when  employed,  as  it 
is,  though  sparingly,  as  a  metallurgic  agent,  is  developed  by  trans- 
mitting aqueous  vapor  over  red-hot  coke.  When  this  gas  is  pro- 
duced by  dissolving  iron  or  zinc  in  a  diluted  acid,  it  is  always 
moist,  and  invaluable  for  the  performance  of  any  delicate  experi- 
ment; for  the  reduction  of  metallic  oxides  it  should  be  dry,  and 
free  from  any  foreign  substance.  Carburetted  hydrogen  or  coal- 
gas  is  used  to  reduce  oxides  under  a  low  heat,  the  carbon  which  is 
precipitated  in  the  formation  of  the  metal  being  removed  by  smelt- 
ing. Hydrogen  or  carburetted  hydrogen  is  applied  in  the  assay- 
ing process,  by  leading  it  into  a  glass  tube  which  contains  the  ore 
specimen  in  a  proper  form  already  heated.  A  gentle  current  of 
gas  is  passed  over  the  ore  until  no  more  is  burned  by  it,  which  is 
manifested  by  the  escape  of  the  gas  in  a  pure  form. 

Next  to  metallic  oxides,  metallic  sulphides  are  of  the  deepest 
3 


34  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

importance  to  the  metallurgist.  Their  reduction  generally  involves 
the  operation  of  roasting,  a  process  to  be  treated  of  hereafter. 

SULPHIDES. — All  metals  combine  more  or  less  with  sulphur,  and 
form  sulphides  when  sulphur  is  brought  into  contact  with  the 
metal,  in  the  absence  of  oxygen  or  chlorine.  When  oxides  are 
treated  with  sulphur  in  sufficient  quantities  to  absorb  all  the 
oxygen  in  forming  sulphuric  acid,  the  sulphur  remaining  com- 
bines with  the  metal.  When  sulphates  are  treated  in  the  presence 
of  carbon  or  hydrogen,  the  oxygen  of  the  sulphuric  acid  is  ab- 
stracted, and  sulphides  remain.  The  chemical  relation  of  sulphur 
to  metal  is  similar  to  that  of  oxygen — that  is,  the  number  and 
equivalents  of  the  sulphides  correspond  with  the  number  and 
equivalents  of  the  oxides  of  the  respective  metals — causing  them 
to  be  more  fluid  and  brittle  when  cold,  and  impairing  their  duc- 
tility when  hot.  Large  quantities  of  sulphur  cause  a  low  degree 
of  fusibility,  which  is  shown  in  the  sulphurets  of  antimony,  lead, 
copper,  and  iron,  the  fusibility  in  each  decreasing  more  rapidly 
than  the  evaporation  of  sulphur.  Iron  pyrites  melts  at  a  low  red 
heat;  but  when  reduced  to  half  its  original  quantity,  by  evaporat- 
ing the  sulphur,  it  requires  a  strong  white  heat  to  melt  the  sul- 
phides. The  presence  of  free  oxygen  is  required  for  the  removal 
of  sulphur ;  nor  can  it  be  removed  entirely  when  carbon,  hydrogen, 
or  any  other  reducing  agent  is  present,  an  oxidizing  influence  and 
thorough  exposure  of  the  metal  to  oxygen  being  necessary. 

Nevertheless,  the  partial  decomposition  which  certain  metallic 
sulphides  undergo,  when  heated  without  the  access  of  atmospheric 
air,  is  to  the  metallurgist  a  consideration  of  importance.  Galena 
treated  in  this  way  suffers  partial  decomposition ;  so,  in  like  man- 
ner, does  the  monosulphuret,  or  monosulphide  of  copper, — a  suf- 
ficient amount  of  sulphur  being  evolved  from,  it  to  yield  disulphide 
of  copper  as  the  permanent  fixed  result.  The  higher  sulphur 
combinations  of  iron,  or  chemically  speaking,  the  sulphur  salts  of 
that  metal,  generated  by  the  combination  of  two  sulphurets  or  sul- 
phides, also  give  a  portion  of  their  sulphur  when  exposed  to  high 
heat  in  close  vessels.  Monosulphide  of  iron,  however,  does  not 
yield  up  any  of  its  oxygen  by  the  mere  process  of  heating  in  close 
vessels.  The  sulphide  of  zinc  (zinc  blende)  is  unchanged  by  the 
highest  temperature ;  so,  in  like  manner,  is  the  sulphide  of  silver. 
The  sulphides  of  gold  and  of  platinum  are  decomposed  when 
heated  into  sulphur  and  their  respective  metals.  The  sulphide  of 
mercury  can  be  distilled  without  change.  Sulphide  of  antimony 
melts  at  a  high  red  heat,  afterwards  distils  over  unchanged.  The 
mono  and  the  ter-sulphide  of  arsenic  (orpiment  and  realgar)  both 
fuse,  and  distil  without  undergoing  any  decomposition. 

By  far  the  more  important  and  usual  method,  however,  of  effect- 
ing the  reduction  of  metallic  sulphides,  consists  in  exposing  them 
to  the  combined  agency  of  heat  and  atmospheric  air — constituting, 
in  point  of  fact,  the  operation  of  roasting.  Usually,  the  change 
which  ensues  during  the  operation  of  roasting,  is  the  conversion 


ON   METALLURGY   CHEMISTRY.  35 

of  sulphur  of  the  sulphide  into  sulphurous  acid  gas,  which  escapes: 
the  original  sulphide,  either  losing  a  part  of  its  sulphur,  and  being 
thus  reduced  to  the  lower  stage  of  sulphurization,  or  else,  losing 
the  whole  of  its  sulphur,  oxygen  is  absorbed  in  place  of  the  latter. 
Occasionally  the  sulphurous  acid  first  generated  absorbs  the  neces- 
sary amount  of  oxygen,  to  change  it  into  sulphuric  acid,  which 
combining  with  the  metallic  oxide  simultaneously  generated,  gives 
rise  to  the  sulphate  of  an  oxide.  This  latter  is  the  case  when 
galena  (sulphide  of  lead)  is  roasted,  the  final  result  of  the  opera- 
tion being  oxide  of  lead,  and  sulphate  of  oxide  of  lead.  This 
change  is  eminently  favorable  to  subsequent  metallurgic  operations 
of  which  galena  is  the  subject.  If  the  galena  be  argentiferous,  the 
following  reactions  ensue :  The  mixture  of  oxide  of  lead  and  sul- 
phate of  the  same  oxide  being  heated  to  whiteness  in  contact  with 
silver  (of  the  argentiferous  galena),  oxidizes  the  silver  by  decom- 
position of  the  sulphuric  acid,  of  the  sulphate  and  oxide  of  lead ; 
hence  there  results  a  mixture  of  oxide  of  silver  and  of  lead — a 
mixture  easily  dealt  with,  and  deoxidized  by  a  subsequent  opera- 
tion. The  sulphide  and  disulphide  of  copper  are  changed  by 
roasting,  into  dioxide  of  copper  and  sulphurous  acid,  and  sulphate 
of  the  oxide  of  copper,  which  latter,  when  the  temperature  is 
raised  to  the  highest  pitch,  evolves  the  whole  of  its  sulphuric  acid 
and  oxygen ;  leaving  metallic  copper.  Monosulphide  of  iron  by 
roasting  undergoes  many  progressive  changes ;  beginning  with  the 
formation  of  protoxide  of  iron  and  sulphurous  acid,  and  ending  in 
the  development  of  sesquioxide  of  iron.  Sulphide  of  zinc  (zinc 
blende)  slowly  changes  under  the  influence  of  roasting,  first  into 
oxide  of  zinc,  and  sulphate  of  the  oxide ;  then  into  subsulphate  of 
the  oxide ;  and,  lastly,  into  oxide  exclusively.  Sublimate  of  bis- 
muth changes,  under  the  influence  of  roasting,  into  oxysulphuret : 
sulphide  of  silver  is  decomposed,  and  yields  metallic  silver.  Ter- 
sulphide  of  antimony  changes  under  roasting  into  antimonious  and 
antimonic  acid.  The  sulphide  and  the  sesquisulphide  of  arsenic 
are  changed  into  arsenious  and  arsenic  acids. 

By  a  modification  of  the  same  process,  sulphide  of  nickel  ad- 
mits of  decomposition  into  a  mixture  of  oxides  and  sesquioxides 
of  that  metal.  Sulphide  of  cobalt  is  also  decomposed  into  a  mix- 
ture of  oxide  of  that  metal  and  sulphate  of  the  oxide.  Finally, 
the  sulphides  of  gold,  platinum,  and  mercury  are  also  reduced  to 
the  metallic  state,  sulphurous  acid  gas  being  evolved. 

Another  element  equal  in  importance  to  oxygen,  requires  the 
attention  of  the  metallurgist.  Chlorine  has  a  tendency  to  induce 
metals  to  crystallize,  and  causes  consequently  fluidity  and  brittle- 
ness.  Chlorine  removes  all  other  matter  from  metals  when  the 
latter  are  in  a  state  of  fusion.  Carbon,  sulphur,  and  phosphorus 
are  drawn  oft*  by  it,  and,  if  the  heat  is  continued,  the  chlorine  it- 
self escapes  with  a  portion  of  the  metals,  but  only  when  a  minute 
proportion  is  present;  it  is  thus  a  powerful  element  in  the  purifi- 
cation of  metals.  Lead  smelted  from  chlorides  is  purer  than  from 


36  THE   PEACTICAL   METAL-WORKER'S   ASSISTANT. 

I 

oxides  and  sulphurets,  and  its  proper  application  to  smelting  and 
refining  purposes  has  a  most  beneficial  influence.  Zinc  does  not 
readily  combine  with  iron  unless  chlorine  be  present ;  it  removes 
oxygen  from  the  protoxides,  thus  purifying  the  surface  and  pre- 
paring it  for  closer  union  with  an  alloy.  All  metals  smelted  under 
the  influence  of  chlorine,  are  inclined  to  oxidize,  unless  it  is  re- 
moved entirely.  It  is  harmless  to  the  metals,  powerful  as  a  means 
of  fluxing  slags  and  ores,  and  producing  fluidity ;  its  use,  therefore, 
ought  to  be  much  more  extended  than  it  has  been. 

CALCINATION,  AND  BOASTING. — These  processes  are  more  fre- 
quently made  use  of  than  any  other  operation  had  recourse  to  by 
the  practical  metallurgist  for  effecting  the  elimination  of  sulphur 
and  other  volatile  substances  from  the  ores  which  are  sulphides  or 
sulphurets.  No  agency  is  so  commonly  employed  as  this,  although 
the  mention  of  a  few  others  should  not  be  omitted.  Amongst  these 
may  be  enumerated  the  combined  application  of  heat  and  aqueous 
vapor ;  of  heat,  and  the  decomposing  agent  of  a  metallic  oxide ; 
finally,  of  heat,  and  the  decomposing  agency  of  alkalies,  alkaline 
earth,  and  their  combinations.  As  a  general  rule,  however,  we 
may  regard  all  other  metallurgic  processes  having  reference  to  the 
decomposition  of  sulphurets,  rather  as  preliminary  assay  operations 
than  the  final  processes  capable  of  adoption  by  the  manufacturer. 

The  process  of  calcination  is  generally  adopted  to  remove  vola- 
tile substances.  Iron  and  zinc  ores  are  heated  to  expel  water  from 
them,  and  iron,  lead  and  zinc,  are  calcined  to  expel  carbonic  acid. 
Water  will  escape  by  the  application  of  a  gentle  heat ;  but  if  much 
clay  be  present  with  the  ore,  it  adheres  tenaciously  to  the  mineral. 
Calcination  is  most  conveniently  performed  in  a  crucible,  because 
no  stirring  of  the  mass  is  required.  The  heat  of  an  air  furnace  is 
generally  sufficient  for  the  performance  of  this  operation. 

The  operation  of  roasting  is  performed  by  various  processes,  de- 
pending on  the  nature  of  the  ore,  the  quantity  of  the  fuel,  and  the 
object  in  view.  Eoasting  in  heaps  in  the  open  air  is  the  method 
most  generally  adopted  with  iron  ore,  pyrites,  and  ores  which  can 
bear  a  strong  fire.  The  operation  consists  in  spreading  over  a 
plane  surface  of  ground  billets  of  wood,  or  lumps  of  mineral  coal, 
from  six  to  eight  inches  thick,  the  interstices  between  the  coarse 
fuel  being  filled  up  with  chips  of  wood,  charcoal,  coke,  or  coal. 
Over  the  fuel  thus  prepared,  according  to  the  kind  of  ore,  is  spread 
a  layer  of  from  twelve  to  twenty-four  inches  in  thickness.  Coarse 
ore,  which  will  bear  a  great  heat,  may  be  piled  pretty  high ;  but 
fine  crushed  ore  from  the  stamps,  and  ores  which  smelt  easily — 
such  as  sulphurets  or  arseniurets — should  not  have  too  much  coal 
in  a  body,  nor  the  ore  piled  over  high. 

Alternate  beds  of  fuel  and  ore  are  thus  formed,  and  roasting 
heaps  accumulated,  which  are  in  many  cases  extremely  large,  re- 
taining the  fire  for  a  long  time. 

Roasting  means  heating  a  substance  to  such  a  point  that  the 
mineral  does  not  melt,  but  at  which  the  volatile  substances  are  ex- 


ON   METALLURGIC   CHEMISTRY.  37 

polled,  and  as  much  oxygen  combined  with  the  ore  as  it  can  absorb. 
In  some  cases,  chlorine,  carbonic  acid,  or  steam,  is  required  along 
with  the  air.  In  other  instances,  the  object  is  to  oxidize  the  ore 
to  a  higher  degree,  to  drive  off  volatile  matter,  or  to  reduce  the 
ore  to  metal,  and  evaporate  it,  as  in  the  case  of  arsenic,  zinc,  and 
antimony. 

The  tendency  of  carbon  to  unite  with  metals  is  slight  and  cir- 
cumscribed. Only  two  metals,  considered  in  a  metallurgic  sense, 
are  amenable  to  this  kind  of  combination, — copper  and  iron. 
Nevertheless,  they  are  the  most  important  of  all  metals ;  and  with- 
out the  carburets  of  iron  (cast-iron  and  steel),  the  most  useful  pur- 
poses to  which  iron  is  now  applied  could  never  have  been  sub- 
served. The  union  of  carbon  with  copper  is  only  productive  of 
inconvenience,  and  the  care  of  the  metallurgist  is  devoted  to  effect 
the  removal  of  the  former  ;  but  in  the  case  of  iron,  though  on  one 
hand  the  removal  of  carbon  is  a  metallurgic  process  highly  de- 
sirable in  order  that  soft  wrought-iron  may  result,  nevertheless,  on 
the  other  hand,  the  problem  of  causing  the  union  of  soft  iron  with 
carbon  is  one  of  importance  equally  great ;  for  on  its  successful 
issue  depends  the  conversion  of  iron  into  steel. 

As  regards  the  theory  of  the  metallurgic  processes  had  recourse 
to  for  effecting  the  removal  of  carbon,  they  are  such  as  naturally 
suggest  themselves  from  a  chemical  consideration  of  the  properties 
of  that  non-metallic  element.  Carbon  is  the  most  ordinary  ma- 
terial of  combustion  known  to  man, — it  is  the  very  type  of  com- 
bustible bodies.  To  deprive  a  carburet  of  its  carbon,  therefore, 
nothing  seems  more  natural  than  to  burn  it  away.  This  is  indeed 
the  process  usually  followed.  It  lies  at  the  basis  of  iron-refining 
and  puddling ;  still  more  obvious  is  the  application  of  the  combus- 
tive  energy  in  the  new  operation  of  Mr.  Bessemer.  Combustion, 
nevertheless,  is  not  the  only  agency  taken  advantage  of  for  effect- 
ing the  removal  of  carbon  from  iron.  A  very  elegant  process  for 
converting  steel  or  cast-iron  into  soft  or  decarbonized  iron,  consists 
in  exposing  an  article  fabricated  of  either  of  these  materials  to 
heat  in  contact  with  iron  oxide.  The  chemical  agencies  thus  in- 
volved are  sufficiently  obvious.  The  oxygen  by  its  affinity  for 
carbon  at  an  elevated  temperature  unites  with  it,  forms  carbonic 
acid,  and  is  evolved,  leaving  the  iron,  to  the  extent  of  the  removal 
of  carbon  thus  effected,  pure.  The  process  in  question  unfortu- 
nately has  but  an  application  restricted  to  a  limited  number  of 
articles  of  inconsiderable  dimensions. 

The  union  of  soft  iron  with  carbon,  or,  in  other  words,  the 
formation  of  steel,  is  usually  effected  by  the  process  known  as 
cementation.  It  consists  in  stratifying  bars  of  iron  with  charcoal 
in  an  iron  case,  and  subjecting  the  whole  to  furnace  heat  until  the 
desired  union  of  the  carbon  with  the  iron  has  been  effected.  The 
chemistry  of  this  union  is  very  peculiar :  furnishing  an  almost 
unique  example  of  combination  ensuing  between  bodies  neither 
fluid  nor  gaseous,  and  contravening  the  long-accepted  chemical 


38  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

axiom,  Corpora  non  agunt  nisi  fiuida.  Perhaps  however,  after  all, 
the  exception  is  more  apparent  than  real.  Laurent  was  of  opinion 
that  the  carbon  thus  entering  into  combination  with  iron,  and 
forming  steel,  became  actually  vaporized  by  the  heat  employed. 
Stammer  advances  another  hypothesis.  lie  believes  that  the  play 
of  affinities  resulting  in  the  union  of  carbon  with  iron,  is  more 
complex  than  had  up  to  his  experiments  been  imagined.  He  in- 
fers that  a  mixture  of  iron  and  oxide  of  that  metal,  when  brought 
to  an  elevated  temperature,  as  in  the  process  of  cementation,  in 
contact  with  carbonic  acid  gas,  robs  the  latter  of  its  oxygen,  thus 
liberating  carbon ;  which,  whilst  still  in  this  condition,  unites  with 
the  metal  to  form  a  carburet. 

Though  the  great  magazine  of  phosphorus  in  creation  is  the 
bones,  and  some  of  the  fluids  of  animals,  nevertheless,  phosphoric 
acid,  combined  "with  oxides  of  metals  and  constituting  phosphates 
of  these  oxides,  give  rise  to  a  small  though  important  group. 
Perhaps  no  element  wherewith  metals  are  naturally  found  in  com- 
bination is  more  difficult  to  separate  effectually,  or  exerts  a  more 
deteriorative  influence  when  present,  even  in  minute  quantities, 
than  phosphorus.  The  processes  usually  had  recourse  to  by  the 
metallurgist  for  effecting  the  separation  of  phosphorus,  are  based 
upon  the  employment  of  some  body  which  manifests  a  strong 
affinity  for  phosphorus  at  elevated  temperatures.  Of  this  kind  is 
chalk,  which  is  sometimes  employed  for  the  purpose  of  separating 
phosphorus  from  iron. 

Occasionally,  though  not  very  often,  the  metallurgist  has  to  deal 
with  the  extraction  of  metals  from  their  salts,  both  oxygenous  and 
haloid.  This  kind  of  extraction,  too,  involves  not  merely  the  dry 
process,  but  also  the  use  of  chlorine  and  of  acids.  Platinum  is  a 
metal  which  has  to  be  dealt  with  exclusively  by  the  process  of 
moist  solution.  Limiting  our  observations  for  the  present  to  the 
case  of  dry  operations,  we  find  that  certain  metallic  salts  are  de 
composable  by  heat  alone,  whilst  others  require  the  agency  of 
some  collateral  reducing  body.  Most  of  the  salts  of  the  metals, 
gold,  platinum,  and  silver,  are  characterized  by  their  facility  of 
complete  decomposition  by  the  mere  application  of  heat.  Of  this 
change,  the  chlorides  of  gold,  of  platinum,  and  the  sulphate  of  the 
oxide  of  silver,  present  familiar  examples.  Many  other  metallic 
salts  when  subjected  to  the  agency  of  heat,  instead  of  being  re- 
duced to  the  metallic  form,  yield  their  several  oxides.  The  sul- 
phate of  iron  and  the  sulphate  of  copper  are  of  this  class, — yield- 
ing, when  sufficiently  heated,  oxides  of  the  respective  metals. 

To  the  practical  metallurgist,  the  most  interesting  series  of  saline 
decomposition  by  fire,  and  deoxidizing  materials,  are  those  in 
which  the  sulphates  of  different  metals  are  concerned.  Sulphates 
differ  merely  from  sulphides  (viewed  as  to  their  composition)  in 
the  mere  circumstance  that  the  former  contain  oxygen,  whilst  the 
latter  do  not.  Hence,  when  sulphates  are  heated  in  contact  with 
coal,  coke,  or  other  deoxidizing  matter,  oxygen  is  frequently  re- 


SPECIAL   METALLURGIC   OPERATIONS.  39 

moved  and  a  sulphide  remains.  The  relative  facility  of  this  kind 
of  decomposition  varies  for  different  sulphates,  but  it  furnishes  a 
type  of  most  of  the  decompositions  which  ensue  when  sulphates 
are  exposed  to  the  combined  agency  of  deoxidizing  materials  and 
heat.  Of  all  the  salts  which  come  under  metallurgic  cognizance, 
the  chlorides  next  to  the  sulphates  are  most  important.  The  re- 
duction of  the  chloride  of  silver  forms  the  basis  of  the  mode  of 
silver  extraction  followed  in  America,  Hungary,  and  various  parts 
of  Europe, — the  reducing  agent  being  iron.  Various  other  methods 
of  reducing  chlorides  to  the  metallic  state  are  followed  in  the  pro- 
cesses of  metallic  assaying ;  and,  although  not  much  involved  in 
the  practise  of  metallurgy  on  the  large  scale,  are  still  of  great  im- 
portance to  the  metallurgist.  The  reduction  of  chloride  of  silver 
by  heating  with  alkalies ;  of  the  chlorides  of  certain  metals  by 
the  contact  of  another  metal ;  and  of  the  chlorides  of  gold  and 
platinum  by  sulphurous,  oxalic,  arsenious,  and  formic  acids,  sul- 
phate of  iron,  and  a  few  other  reagents, — are  familiar  examples. 


CHAPTER  II. 

SPECIAL   METALLURGIC   OPERATIONS. 

WE  now  come  to  the  principles  on  which  metallurgic  processes 
are  based,  and  the  practical  application  of  these  principles.  Me- 
chanical and  chemical  sciences  are  here  involved, — the  former  to 
effect  a  due  comminution  of  the  extracted  ore  from  foreign  impu- 
rities ;  th'e  latter  to  complete  this  separation  and  evolve  the  metal 
in  a  condition  as  near  that  of  absolute  purity  as  may  be  possible 
or  desirable.  The  mechanical  part  of  metallurgy  .can  only  be  dis- 
cussed advantageously  hereafter ;  in  this  introduction,  therefore, 
we  shall  limit  ourselves  to  an  exposition  of  the  chemical  princi- 
ples of  metallurgic  operations. 

Between  abstract  chemistry,  if  the  term  be  allowable,  and  tech- 
nical chemistry,  there  seems  a  wide  difference  at  a  first  glance. 
The  only  real  distinction  between  them,  however,  will  be  found  to 
be  one  of  degree.  The  principles  are  the  same,  and  both  are 
amenable  to  the  same  laws :  the  laboratory  chemist,  however,  hav- 
ing more  agents  at  his  command — being  little  amenable  to  consid- 
erations of  profit — more  readily  carries  these  indications  out  to 
their  several  finalities. 

The  chemical  part  of  metallurgy  has  for  its  object  the  separation 
of  various  substances,  and  the  isolation  of  a  few,  by  the  operation 
of  chemical  affinities ;  being  amenable  thus  to  ordinary  rules  of 
chemical  guidance,  the  first  of  which  is  based  upon  the  law  that 
chemical  action  takes  place  (with  few  exceptions,  and  those  doubt- 


40  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

fill)  between  portions  of  matter  the  cohesion  of  which  is  slight. 
Reversing  the  proposition,  we  may  also  say  that  chemical  decom- 
position is  effected  by  loosening  the  state  of  cohesive  affinity. 

Of  the  three  forms  in  which  matter  is  found,  namely,  the  solid, 
the  fluid,  and  the  gaseous  state,  respectively,  it  is  evident  that  the 
two  former  are  most  under  the  control  of  cohesion ; — gases,  indeed, 
are  often  said  to  be  absolutely  devoid  of  cohesion  as  between  their 
particles ;  a  proposition  which,  though  chemically  unsound,  may 
be  considered  to  be  practically  correct. 

The  metallurgist,  then,  in  effecting  his  numerous  decompositions, 
proceeds  to  diminish  the  cohesive  force  by  which  the  particles  of 
his  material  are  held  together.  He  begins  by  mechanical  pro- 
cesses— by  hammering,  grinding,  stamping,  etc.  When  these  can 
go  no  further,  he  has  recourse  to  chemical  means.  The  problem 
now  is  to  liquefy,  or  to  gasify — usually  the'  former,  though  many 
important  mineralogical  operations  involve  the  production  of  gas, 
or  at  least  of  vapor ;  for  gases  and  vapors  may  be  generally  re- 
garded as  identical.  Supposing  liquefaction  to  be  the  object  in 
view,  the  metallurgist  has  the  choice,  theoretically,  of  dissolving 
his  substance  in  chemical  menstrua  or  of  fusing  it  by  heat.  The 
former  alternative  is  superior  in  the  correctness  of  its  results,  and 
for  that  reason  is  usually  adopted  by  the  laboratory  chemist ;  but 
it  is  so  expensive,  and  slow,  and  inapplicable  where  large  masses 
are  concerned,  that  it  is  never  adopted  by  the  metallurgist,  other- 
wise than  by  necessity.  "With  the  exception  of  platinum  and  its 
associates,  all  worked  exclusively  by  the  process  of  solution  in 
chemical  menstrua — by  the  moist  process,  in  point  of  fact — gold 
occasionally,  and  a  few  of  the  common  metals  under  certain  pecu- 
liar conditions,  the  moist  process  of  effecting  solution  of  cohesive- 
ness  may  be  regarded  as  beyond  the  pale  of  applied  metallurgy. 

We  have  thus  limited  the  metallurgist  to  the  agency  of  fire ; 
and  we  have  assumed,  as  is  most  usual,  that  the  object  of  furnace- 
heat  shall  be  to  reduce  the  material  to  the  condition  of  fluidity. 
We  might,  therefore,  at  once,  pursuing  the  thread  of  demonstra- 
tion, enter  upon  the  theory  and  opera- 
tion of  fluxes,  were  it  not  that  a  case 
of  effecting  chemical  decomposition 
by  the  formation  of  gas  or  vapor  some- 
times precedes  and  therefore  claims 
precedence  in  our  remarks.  Many  ores 
either  contain  substances  naturally 
volatile  or  which  generate,  under  the 
combined  influence  of  heat  and  air, 
volatile  combinations.  Sulphur  and  ar- 
senic are  prominent  examples  of  this 
kind,  and  serve  well  to  illustrate  that 
application  of  a  chemical  law  which 
is  involved  in  the  'metallurgic  pro- 
cess of  roasting  or  calcination ;  respecting  which  sufficient  par- 


SPECIAL   METALLURGIC   OPERATIONS. 


41 


ticulars  in  an  earlier  part  of  this  introduction  have  been  already 
given. 

The  process  of  roasting  is  variously  modified  to  accord  with  the 
peculiarities  of  certain  metals,  or  to  gain  the  precise  end  desired. 
In  some  cases  it  is  no  more  than  the  process  known  to  chemists  as 
dry  distillation;  in  other  cases,  its  success  depends  on  the  com- 
bined agency  of  an  atmospheric  current  as  applied,  for  instance, 
to  the  evolution  of  antimony. 

Though  the  metallurgic  operation  of  roasting  involves  a  well- 
marked  case  of  gasefaction  applied  to  a  definite  end,  yet  similar 
results  are  obtained  under  different  forms  of  apparatus.  The  oper- 
ations involved  in  the  production  of  mercury  and  zinc  are  famil- 
iar examples.  Both  these  metals 
are  remarkable  for  their  extreme 
volatility,  the  first  especially  so : 
hence  the  process  of  metallurgy 
adopted  in  their  production  is  not 
one  of  smelting,  properly  so  calFed, 
or  of  roasting  as  popularly  under- 
stood, but  as  one  of  veritable  dis- 
tillation. Mercury  is  frequently 
produced  by  simple  sublimation, 
without  the  addition  of  flux  or 
coal,  so  also  is  arsenic;  but  in 
most  instances  carbon,  and  such 
substances  as  decompose  the  ore, 
are  added.  In  the  mercury  dis- 
tillation-furnace here  annexed 
(Fig.  1)  the  similarity  to  ordinary 
distillation  vessels  and  receivers 
is  sufficiently  obvious;  not  very 
remote,  either,  is  the  similarity  to 
the  ordinary  distillation  apparatus 
shown  by  the  Belgian  furnace  for 
zinc  extraction  (Fig.  2).  There  is 
no  ^difficulty  in  smelting  zinc  un- 
der cover  of  carbonate  of  soda 
and  potash  with  carbon,  but  this 
is  an  expensive  flux,  and,  when 
not  closely  watched  when  fluid, 
the  loss  may  exceed  the  value  of 
the  metal  obtained.  It  is  for  these 
reasons  found  good  economy  to 
mix  the  zinc  blende  with  iron; 
although  the  heat  required  by  this 
process  is  much  greater  than  for 
smelting,  it  is  asserted  that  distil- 
lation is  the  cheaper  process.  The  apparatus  here  figured  is  a  ver- 
tical section  of  a  furnace  with  its  retorts,  of  which  there  are  as 


42 


THE   PRACTICAL   METAL-WORKEE'S  ASSISTANT. 


many  as  twenty-two.  They  are  placed  about  two  inches  apart 
from  each  other  to  admit  the  passage  of  hot  gases  from  the  fur- 
nace. The  metal  which  condenses  in  these  gently-sloping  pipes, 
requires  to  be  raked  out  every  two  _  hours  to  prevent  them  from 
being  choked  up,  and  twelve  hours"  are  required  to  work  off  a 
charge.  Perhaps  the  various  parts  of  an  English  zinc  oven  may 
not  be  quite  so  suggestive  of  a  distillatory  process ;  nevertheless 
they  are  representatives  of  a  form  of  distillatory  apparatus  per- 
haps more  ancient  than  any — a  form  known  to  the  alchemists,  and 
described  by  them  under  the  name  of  destillatio  per  descensum,  (Fig. 
3).  A  vertical  section  is  given  of  this  apparatus.  They  are  some- 
times round,  sometimes  square,  having  six  or  eight  crucibles  in- 
serted in  one  furnace,  an  iron 
pipe  inserted  into  the  bottom 
of  the  crucible  conducting  the 
metal  into  a  reservoir,  which 
is  filled  with  water. 

The  theory  of  this  process 
is  very  simple :  the  oxide  of 
zinc  mixed  with  carbon  is  re- 
duced to  metal  on  being  ig- 
nited; and  the  metal,  being 
volatile,  passes  in  the  form  of 
vapor  to  the  receiver,  where  it 
is  condensed  in  the  form  of  a 
crude  impure  metal,  which  re- 
quires a  further  process  of  re- 


Fig.  3. 


fining  before  it  is  fit  for  commercial  purposes. 

FLUXES. — Assuming  the  process  of  roasting  to  have  been  neces- 
sary and  to  have  been  applied,  and  that  a  metallic  substance  still 
remains  to  be  extracted  from  the  non- volatile  residue,  a  process  of 
fusion  must  be  had  recourse  to ;  it  is  called  smelting.  A  slight 
chemical  consideration  of  the  materials  wherewith  metals  are  or- 
dinarily combined,  will  bring  to  mind  the  fact  that  some  are  really 
or  practically  infusible.  But  fusion  the  metallurgist  must  have : 
the  theoretical  choice  was  before  him  of  choosing  between  the 
moist  or  solvative,  and  the  dry  or  igneous  process  of  effecting 
liquidity.  He  was  driven  by  practical  considerations  to  accept  the 
latter ;  therefore  fusibility  is  a  condition  so  indispensable  to  success 
in  his  future  operations  that  he  must  have  it.  How,  then,  was  he 
to  solve  the  problem  of  effecting  the  fusibility  of  things  which 
are  by  their  nature  infusible  ?  Chemistry  renders  the  solution  of 
this  problem  easy :  there  are  many  substances  which,  though  in- 
fusible when  heated  by  themselves,  fuse  readily  enough  when 
heated  in  combination ;  hence  arises  the  theory  of  fluxes  and  flux- 
ing, these  terms  being  respectively  applied  to  substances  which 
impart  igneous  fluidity,  when  heated  with  other  substances,  and  to 
the  manner  of  using  them.  Silica,  or  silicic  acid,  is  an  infusible 
body  when  heated  alone ;  nevertheless  it  fuses  when  sufficiently 


SPECIAL   METALLURGIC   OPERATIONS.  43 

heated  in  contact  with  potash,  soda,  or  their  respective  carbonates ; 
and  less  readily  when  heated  in  contact  'with  alkaline  earths. 
Hence  if  the  metallurgic  problem  were  to  present  itself,  of  ex- 
tracting a  metal  by  fire  from  a  mixture  of  the  same  with  silica 
(chemically  silicic  acid),  potash,  or  soda,  or  their  respective  car- 
bonates, would  be  had  recourse  to  in  preference  to  all  others,  if 
considerations  of  profit  and  loss  did  not  intervene.  The  price  of 
the  alkalies  and  carbonates  of  alkalies  does  not  admit  of  their 
common  application  to  the  purposes  of  a  flux  on  the  large  metal- 
lurgic scale ;  wherefore  the  smelter,  not  being  able  to  use  the  flux 
which  chemistry  proclaims  to  be  the  best,  contents  himself  with  a 
substitute  as  near  to  the  theoretic  quality  as  may  be  practicable. 
Thus  where  alkalies,  or  carbonates  of  alkalies,  would  have  been 
employed  to  facilitate  igneous  fusion  in  the  laboratory,  and  on  the 
small  scale — probably  lime,  or  carbonate  of  lime,  would  be  em- 
ployed in  the  larger  representation  of  the  process  as  performed  by 
the  metallurgist. 

Not  only  do  the  alkalies  and  their  carbonates  perform  the  func- 
tions of  fluxes  to  silicic  acid,  but  also  to  several  metallic  oxides ; 
amongst  which  those  of  lead,  copper,  and  iron,  may  be  cited  as 
familiar  examples.  Every  person  knows  that  flint-glass,  as  it  is 
called,  contains  oxide  of  lead;  that  black  bottle-glass  contains  ox- 
ide of  iron, — combinations  which  illustrate,  perhaps,  as  well  as 
any  we  could  adduce,  the  quality  of  the  alkalies  which  imparts  to 
them  the  power  of  a  flux.  When  it  is  considered  that  nearly  all 
the  colors  which  can  be  imparted  to  glass,  nay,  which  are  imparted 
to  porcelain  and  enamel,  are  referable  to  combinations  of  metallic 
oxides  with  silicic  acid,  a  still  further  notion  will  be  conveyed  of 
the  extensive  range  of  combination  which  raaj  be  produced  by 
silicic  acid  under  the  influence  of  igneous  fusion. 

Next,  perhaps,  to  potash  and  soda,  in  respect  to  its  large  range 
of  agency  as  an  igneous  flux,  comes  borax.  Seldom  is  it  that  the 
assayer  in  his  laboratory  operations  on  mineral  ores  by  fire  dis- 
penses both  with  alkalies  and  with  borax ;  but  here  in  this  case, 
again,  considerations  of  expense  restrict  the  application  of  this 
material  to  the  laboratory,  and  the  smelter  is  obliged  to  content 
himself  with  fluxes  much  lower  in  the  scale  of  chemical  power  and 
efficiency.  Perhaps,  however,  there  may  not  be  so  many  advan- 
tages lost  from  the  non-employment  of  laboratory  fluxes  on  the 
large  scale  as  is  sometimes  imagined.  To  adopt  soda,  or  potash, 
or  borax,  though  compatible  with  the  economical  arrangements  of 
the  laboratory  chemist,  who  will  not  hesitate  to  ruin  a  crucible  at 
each  operation,  might  still  accord  very  ill  with  the  economy  of 
furnace-building.  The  alchemists  tried  to  discover  a  fluid  which 
should  have  the  property  of  dissolving  all  things  wherewith  it 
might  come  into  contact.  They  neglected  to  reflect  that  a  neces- 
sity would  arise  for  a  vessel  to  keep  it  in.  It  might  be  thus  with 
metallurgists  on  the  large  scale,  if  laboratory  fluxes  were  cheap 
enough,  and  plentiful  enough,  to  be  adopted  on  the  large  scale. 


44  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

Though  the  number  of  fluxes  which  the  metallurgist  has  at  his 
command  for  large  operations  of  smelting  be  inconsiderable  by 
comparison  with  those  employed  in  laboratory  operations,  never- 
theless the  process  of  assaying  is  one  so  important  to  the  metal- 
lurgist that  every  flux  known  to  the  chemist  deserves  his  con- 
sideration. Under  the  subject  of  assaying,  therefore,  to  be  ad- 
verted to  hereafter,  the  chemical  agents  will  be  fully  discussed. 

The  preliminary  operation  of  dressing  having  been  performed 
on  a  mineral,  also  the  further  operation  of  roasting  if  necessary, 
the  final  operation  of  smelting  naturally  follows.  After  the  gen- 
eral statement  we  have  given  of  the  nature  and  properties  of  fluxes, 
it  will  be  seen  that  the  operation  of  extracting  metal  from  a  metal- 
lic ore  by  smelting,  consists  in  subjecting  it  to  furnace -heat  in  ad- 
mixture with  some  flux, — the  object  of  the  latter  being  twofold. 
Primarily  to  liquefy  and  dissolve  away  refuse  matters  by  themselves 
infusible ;  and,  secondarily,  in  some  cases  to  aid  the  decomposition, 
by  the  result  of  which  the  metal  is  evolved  from  its  combinations. 
It  remains  now,  for  the  completion  of  our  sketch  of  the  appliances 
of  metallurgy,  that  we  indicate  the  peculiarities  of  the  different 
furnaces,  and  the  appendages  by  means  of  which  the  operation  of 
smelting  is  effected. 

FURNACES. — The  various  forms  of  furnaces  admit  of  division 
into  two  well-marked  primary  classes.  One  class  in  which  the 
material  to  be  acted  upon  is  brought  in  direct  contact  with  fuel ; 
the  other  class  in  which  the  acting  fuel  and  the  material  acted  upon 
are  separated  from  each  other. 

Either  of  these  furnaces  may  be  supplied  with  air  from  a  blast 
of  some  kind,  or  they  may  depend  for  their  supply  of  air  on  the 
draught  of  a  chimney-shaft.  Accordingly,  in  reference  to  these 
peculiarities  we  establish  a  division  of  furnaces  into  blast-furnaces 
and  wind-furnaces.  The  first  class  of  furnaces,  or  those  in  which 
the  material  and  the  fuel  are  placed  in  contact,  differ  in  form  and 
general  intention,  according  to  certain  obvious  peculiarities  of  con- 
struction. Some  merely  consist  of  a  flat  expansion  or  hearth,  upon 
which  the  fuel  may  either  smoulder  and  develop  a  long-continued 
gentle  heat,  as  in  the  ordinary  lime-kiln ;  in  the  kiln  or  hearth 
upon  which  copper  pyrites  and  copper  matte  are  heated  or  roasted, 
and  in  many  similar  forms  of  hearth -furnace  employed  by  metal- 
lurgists, chiefly  to  accomplish  roasting  operations ;  or  the  fuel  may 
be  urged  to  almost  the  highest  degree  of  heat  of  which  a  furnace 
is  capable,  as  we  see  exemplified  in  the  smith's  forge.  A  modifica- 
tion of  this  form  of  furnace  is  employed  in  Great  Britain  in  the 
smelting  of  considerable  quantities  of  lead  ore.  If,  however,  it  be 
desired  to  raise  the  intensity  of  furnace-heat  to  the  highest  point, 
the  hearth-construction  of  furnace  must  give  place  to  others  on  the 
type  of  a  cylindrical  or  conoidal  vessel.  Perhaps  the  highest 
degree  of  furnace-heat  known,  is  yielded  by  large  iron  blast- 
furnaces. 

Usually  the  aid  of  an  artificial  blast  is  only  sought  for  the  first 


SPECIAL   METALLURGIC   OPERATIONS.  45 

division  of  furnaces,  namely,  those  in  which  the  fuel  and  the  ma- 
terial to  be  acted  upon  are  employed  together.  This,  however,  is 
by  no  means  universal.  To  furnaces  in  which  the  substance  acted 
upon  does  not  come  into  contact-  with  the  fuel  used,  the  term  re- 
verberatory  furnace  is  applied.  Amongst  other  metallurgic  ap- 
plications of  this  third  kind  of  furnace,  those  of  iron  puddling  and 
balling  may  be  especially  mentioned. 

Still  more  important  than  an  acquaintance  with  the  various 
terms  conventionally  applied  to  furnaces,  to  the  form  of  their  con- 
struction, or  the  objects  they  are  intended  to  subserve,  is  a  full 
comprehension  of  the  chemical  principles  upon  which  their  effi- 
ciency depends ;  aud  with  that  we  have  to  deal  here.  A  furnace 
may  be  said  to  be  a  contrivance  for  giving  the  best  practical  effect 
to  the  laws  of  combustion  as  directed  to  some  practical  end.  It 
will  hence  be  proper  that  we  take  a  casual  glance  at  these  laws,  as 
a  branch  of  chemical  physics  applied  to  metallurgy.  All  ponder- 
able bodies  are  conventionally  divided  into  combustibles  and  sup- 
porters of  combustion ;  thus,  for  example,  coal  is  said  to  be  com- 
bustible, and  air,  or  rather  the  oxygen  contained  in  the  air,  is  said 
to  be  the  supporter  of  combustion  under  the  "usual  circumstances 
involved  in  the  ordinary  combustion  of  coal.  This  division,  though 
usual,  is  purely  conventional ;  the  function  of  fbmbustion  being,  in 
point  of  fact,  a  result  of  chemical  action  between  two  agents,  and 
appertaining  to  both ;  whence,  in  strict  language,  coal  or  the 
materials  of  coal  and  atmospheric  oxygen  gas  are  equally  the  sub- 
jects of  combustion,  and  therefore  combustible.  Nevertheless  the 
conventional  distinction  between  combustibles  and  supporters  of 
combustion  has  attained  a  certain  significance,  rendering  it  con- 
venient of  application  in  a  practical  sense.  If  we  mentally  review 
the  substances  of  combustion  they  are  such  as  most  obviously 
present  themselves  to  common  observation.  Before  the  employ- 
ment of  hydrogenous  gas  for  heating  and  illuminative  purposes, 
all  popularly  known  combustibles  presented  the  qualities  of  being 
visible  and  tangible ;  their  combustive  property  was  known  long 
before  the  theory  of  combustion  had  been  suspected,  and  at  periods 
when  the  existence  of  gases  was  looked  upon  as  matter  to  be 
doubted  or  disbelieved;  no  wonder,  then,  that  the  new  power  in- 
volved in  the  combustive  operation  was  so  long  unsuspected,  and, 
when  discovered,  allowed  a  subordinate  place  only,  though  all 
material  bodies  be  impressed  with  the  quality  of  ministering  to 
the  combustive  function,  either  in  the  sense  of  a  combustible  or  a 
supporter  of  combustion — nevertheless,  the  bodies  which  are  df  a 
nature  enabling  man  to  realiee  them  as  combustibles  are  few. 
Above  all  things  it  is  necessary  to  the  efficiency  of  a  combustible, 
practically  considered,  that  the  result  of  its  combustion  shall  be 
gaseous.  When  pure  charcoal  burns,  no  residue  or  ashes  are  left ; 
the  sole  result  of  combustion  is  a  gas,  which,  by  reason  of  its 
nature,  passes  away.  Even  when  ordinary  charcoal  is  used,  the 
ashes  are  but  inconsiderable ;  and  if  coke  or  coal  be  the  fuel  em- 


46  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

ployed,  the  amount  of  solid  residue  still  bears  but  inconsiderable 
proportion  to  the  mass  of  fuel  originally  used.  Guided  by  the 
limiting  consideration  of  gaseous  products,  it  is  easily  seen  that  the 
only  class  of  bodies  having  any  claim  to  be  regarded  as  combus- 
tible, in  a  practical  sense,  are  two — the  hydrogenous  and  the  car- 
bonaceous forms.  All  the  naturally  occurring  fuels  present  us 
with  a  mixture  of  these :  coal  in  all  its  varieties,  wood,  and  peat,  so 
obviously  bearing  out  the  proposition  that  no  illustration  is  re- 
quired. Keference  to  the  chemical  condition  of  carbon  and  of 
hydrogen  respectively  when  burned  will  bring  to  mind  the  fact, 
that  in  proportion  as  hydrogen  predominates,  so  will  the  combus- 
tion be  more  flaming ;  and  conversely,  in  proportion  as  hydrogen 
is  absent,  so  will  the  resulting  combustion  be  of  the  incandescent 
or  glowing  kind,  like  that  of  ignited  charcoal.  Of  late  much 
attention  has  been  devoted  to  the  problem  of  ascertaining  the  corn 
parative  value  of  fuels ;  but  we  may  here  remark  that  the  deduc- 
tions have  not  been  attended  with  a  corresponding  amount  of 
practical  success,  chiefly  because  of  their  too  literal  and  exclusive 
application. 

The  real  amount  of  heat  capable  of  being  developed  by  the  given 
weight  of  a  combustible  by  refined  chemical  means,  is  so  involved 
with  other  conditions  in  practice  as  to  be  of  itself  little  worth. 
The  mechanical  aggregation  of  any  particular  combustible,  is  at 
least  an  element  of  consideration  of  equal  value  to  its  real  chemical 
power  of  evolving  heat.  The  truth  of  this  proposition  is  amply 
borne  out  by  the  familiar  operations  of  coking  and  charcoal 
making.  Weight  for  weight,  coal  has  more  combustible  heat-gen- 
erating matter,  than  coke  and  wood,  or  than  the  charcoal  made 
from  wood.  Nevertheless  the  mechanical  or  physical  conditions 
of  coal  and  wood  are  such,  that  they  are  totally  unadapted  to  many 
of  those  heat-generating  operations  which  coke  and  charcoal  effi- 
ciently subserve.  The  fixedness  of  carbon  and  the  volatility  of 
hydrogen  suggest  the  cases  in  which  the  superior  absolute  heat- 
developing  power  of  the  former  would  be  more  than  compensated 
by  the  inferior  localized  heat-generating  power  of  the  latter.  Ac- 
cordingly, theory  indicates,  and  practice  confirms  the  indication, 
that  in  all  cases  wherever  it  is  desired  to  bring  the  fuel  and  the 
material  to  be  fused  into  actual  contact,  a  non-hydrogenous  fuel, 
such  as  coke  and  charcoal,  is  to  be  sought.  When,  however,  the 
substance  to  be  acted  on  is  situated  apart  from  the  fuel,  then  the 
latter  may,  though  not  necessarily  so,  be  hydrogenous.  Even  the 
carbonaceous  fuels  may  be  made  to  yield  flame  by  particular  treat- 
ment. If  atmospheric  air  be  supplied  to  the  extent  of  ministering 
to  the  full  wants  of  carbonaceous  combustion,  there  is  no  flame, 
because  the  carbon  is  immediately  and  entirely  changed  into  car- 
bonic acid ;  if,  however,  the  supply  of  air  be  more  scanty,  or  if  the 
fuel  be  so  arranged  that  the  carbonic  acid  originally  formed  has  to 
permeate  white-hot  carbon,  it  is  practically  deoxidized,  changed 
into  carbonic  oxide,  a  combustible  gas :  hence  flame  ensues.  So 


SPECIAL  METALLURGY   OPERATIONS.  47 

important  Jid  it  seem  to  obtain  a  strongly-flaming  fuel  for  use  in 
the  reverberatory  furnace  operation  of  iron  puddling,  that  not 
merely  gas-yielding  bodies,  but  gaseous  mixtures  have  actually 
been  proposed,  and  to  a  limited  extent  carried  into  practice ;  more- 
over, the  unconsumed  inflammable  gases  which  escape  from  iron- 
"blast  smelting  furnaces  is  sometimes  collected,  and  applied  as  a 
heating  agent.  Probably,  however,  the  latter  application  is  one  in 
a  wrong  direction.  It  may  be,  and  probably  is  true,  that  if  an 
escape  of  combustible  gas  take  place  from  one  of  these  furnaces 
sufficient  to  be  of  consequence  as  a  heat-giving  agency,  this  cir- 
cumstance suggests  an  imperfection  in  th'e  economy  of  the  furnace. 
Instead  of  endeavoring  to  collect  the  escaping  gas  to  be  used  as 
a  combustible  therefore,  it  might  be  preferable  to  take  measures 
for  burning  the  gas  while  yet  in  the  furnace,  thus  rendering  the 
heat  developed  by  its  combustion  effective  in  the  furnace  operation. 
Many  iron-manufacturers  who  at  one  time  used  the  inflamma- 
ble gases  of  their  furnaces  as  a  heating  agent,  have  since  aban- 
doned the  practice ;  and  a  sort  of  inferential  testimony  to  the  disad- 
vantage of  the  process  is  afforded  by  the  well-marked  and  ingenious 
effects  developed  in  the  primary  operation,  if  the  collecting  of  the 
gaseous  results  be  made  lower  down  in  the  body  of  the  furnace  than 
a  line  coincident  with  the  termination  of  the  first  third  of  the 
vertical  height  of  the  furnace  shaft.  If  the  gases  be  withdrawn 
higher  up  than  this,  they  are  mixed  with  so  much  combustible 
material  such  as  nitrogen  and  carbonic  acid,  that  they  are  worthless 
as  heating  agents ;  if  they  are  withdrawn  lower  down,  the  smelt- 
ing operation  is  prejudiced  by  the  removal  of  carbonic  oxide 
— an  important  agent  in  accomplishing  the  reduction  of  iron 
ore. 

The  subjoined  table  will  show  the  composition  of  the  gases  thus 
withdrawn  from  iron  furnaces  in  three  different  works,  i.  e.  Veck- 
erhagen,  Clerval,  and  Barum : 

(I.)  isjft.  *  (II.)  18ft. 

Nitrogen   ....  62-47  —  58-115  .  .  64«28  —  63-20 

•      Carbonic  acid     .     .     3'44  —  13*76     .  .     4-27  —  12-46 

Carbonic  oxide  .     .  30-08  —  22'65     .  .  29-17  —  18-57 

Carburetted  hydrogen  2'24  —    0-00     .  .     1-23  —    1-27 

Hydrogen      .     .     .     1-77—    1-77     .  .     1'05  —    4-51 


100-00     100-00          100-00     100-00 

Regarding  the  composition  of  the  gases  from  Veckerhagen  and 
the  gases  from  Barum  (I.)  and  those  from  Clerval  and  Barum  (II.) 
as  almost  mutually  identical,  a  mean  may  be  taken  in  hereafter 
calculating  their  relative  values.  The  following  table  represents 
the  mean  composition  by  volume : 


48  THE   PRACTICAL   METAL-WOEKER'S   ASSISTANT. 

Veckerhagen  and  Clerval  and 

Biirum  (1.)  Barum  (II.) 

Mean.  Mean. 

Nitrogen 63'4 607 

Carbonic  acid  .    .....     .  3'9 13'1 

Carbonic  oxide    .     ,     .     .     .  29'6 2O6 

Carburetted  hydrogen  .     .     .  1*7  .     .     .  *  .     .  0'6 

Hydrogen 1-4  .....  5*0 

100-00  100-00 

* 

A  composition  by  volume  which  accords  with  the  following  com- 
position by  weight: 

A.  B. 

Nitrogen 63'4 59-7 

Carbonic  acid 5-9 19*4 

Carbonic  oxide 29'6 20'2 

Carburetted  hydrogen  ...  TO 0'3 

Hydrogen 01 0'4 


100-00  100-00 

The  former,  however,  are  not  the  only  gaseous  constituents 
which  are  evolved  unconsumed  from  coal  and  coke-burning  fur- 
naces. Occasionally  hydrogen  and  carburetted  hydrogen  are  de- 
veloped, as  was  found  to  be  the  case  by  Ebelmen  in  the  gaseous 
evolutions  of  furnaces  at  Yienne  and  Port  L'Eveque. 

While  on  the  subject  of  the  utilization  of  combustible  gases 
which  escape 'from  iron-furnaces,  it  may  be  well  to  indicate  that  the 
idea  first  originated  in  1812,  at  which  date  Abberlet  obtained  a 
patent  for  the  application  of  gases  thus  developed  to  metallurgical 
purposes.  In  1830  an  attempt  was  made  at  Holsbriicke,  near  Frei- 
berg, to  employ  the  flame  of  coal-gas  as  the  source  of  heat  for 
cupellation.  In  neither  case,  however,  was  the  proposition  carried 
out  to  complete  success,  or,  indeed,  fully  inaugurated.  The  merit 
of  accomplishing  the  latter  is  due  to  Faber  du  Faur,  who,  about 
the  year  1838,  tested  the  value  of  the  suggestion  on  the  furnaces 
of  some  iron-works  at  Wiirtemberg. 

However  doubtful  the  advantages  may  be  of  collecting  gaseous 
matters  from  iron  furnaces  and  utilizing  them  as  fuel,  the  prospec- 
tive advantages  of  employing  combustive  gases  in  this  way  have 
seemed  considerable  enough  to  warrant  the  invention  of  several 
contrivances  with  this  end  specially  in  view.  In  France,  and  more 
especially  in  Silesia,  combustible  materials  are  gasefied  with  spec- 
ial reference  to  employment  of  the  resulting  gas  in  furnace  opera- 
tions. We  have  already  adverted  to  the  disadvantages  which 
the  iron-master  encounters  from  the  necessity  he  is  under  of 
smelting  with  a  fuel  holding  injurious  quantities  of  sulphur,  phos- 
phorus, and  some  other  impurities.  Eeflection  on  these  conditions 


SPECIAL   METALLURGIC   OPERATIONS. 


49 


will  indicate  the  advantages  which  should  theoretically  accrue  from 
the  substitution  of  gaseous  combustibles  devoid  of  such  matters. 
Practically,  however,  much  cannot  be  said  in  favor  of  gaseous 
iron-smelting. 

Some  few  years  since  considerable  interest  was  excited  by  a 
patent  taken  out  by  Mr.  Keece  for  the  conversion  of  peat  into 
valuable  products  by  a  modified  process  of  destructive  distillation. 
One  of  the  subsidiary  propositions  involved  by  this  patent  was  the 
employment  of  the  gaseous  matters  evolved  to  effect  the  smelting 
of  iron.  It  was  hoped  that  the  result  would  be  equal  to  Swedish 
charcoal  wrought- iron,  and  that  we  should  be  rendered  totally  in- 
dependent of  that  source  for  our  supply.  The  process  of  Mr. 
Keece,  however,  has  in  no  way  answered  the  expectations  enter- 
tained of  it.  One  of  the  most  powerful  incentives  to  the  employ- 
ment of  gaseous  combustibles  has  arisen  in  countries  where 
charcoal  fuel  is  much  used, — and  from  the  consideration  of  the 
circumstance  that  the  mechanical  conditions  of  powdered  charcoal 
render  it  unadapted  to  furnace  operations.  Every  person  who  has 
been  accustomed  to  work  with  charcoal  as  fuel,  even  on  the  small- 
est scale,  must  have  experienced  the  loss  which  arises  from  the 
pulverulent  quality  of  that  substance,  and  can  readily  imagine  that 
this  disadvantage  increases  when  charcoal  is  employed  on  the  man- 
ufacturing scale.  Now  the  powder  thus  resulting,  though  unfit  to 
be  employed  in  the  condition  of  furnace  fuel,  is  in  the  best  state 
of  mechanical  disaggregation  to  be  converted  into  gas.  Perhaps 
the  most  successful  apparatus  for  effecting  the  gasification  of  char- 
coal is  one  used  in  France,  and  constructed  on  the  model  of  an 
iron-smelting  furnace. 

It  consists  of  a  funnel  or  hopper  into  which  the  powdered  char- 
coal is  thrown,  which  latter  sinks  by  its 
own  weight  into  the  body  of  the  furnace, 
and  is  there  exposed  to  a  current  of  air 
forced  upwards  through  it,  by  a  blast-pipe, 
which  enters  the  furnace  underneath.  If 
the  hopper  be  kept  well  filled  with  charcoal 
powder,  no  gas  will  escape  from  its  orifice ; 
but  the  entire  result  of  gasification  will  find 
exit  by  a  tuyere,  and  this  under  considera- 
ble pressure.  The  apparatus  in  question  is 
specially  designed  for  the  combustion  of 
charcoal  powder  ;  lump  charcoal  may  how- 
ever be  used  if  the  furnace  or  hopper  be 
supplied  with  a  cover  to  retain  the  gaseous 
products  of  combustion.  Independently  of 
the  mere  question  as  to  the  advantages  or 
disadvantages  of  gaseous  combustibles  ab- 
stractly considered,  the  process  of  gas  gen- 
eration by  the  transmission  of  atmospheric  air  through  burning 
materials  is  attended  with  collateral  difficulties.  If  care  be  not 
4. 


Fig.  4. 


50  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT.  • 

taken  to  prevent  the  admission  of  more  atmospheric  air  than  is 
actually  required  to  subserve  the  process  of  slow  combustion,  an 
explosive  mixture  is  formed,  and  danger  from  that  cause  is  immi- 
nent. On  the  other  hand,  if  the  gaseous  materials  be  allowed 
to  escape  unconsumed,  the  attendant  workmen  are  liable  to  be 
poisoned. 

NATURAL  AND  ARTIFICIAL  BLASTS. — Next  in  relation  to  fur- 
nace-heat, we  have  to  consider  the  various  means  had  recourse  to 
for  producing  atmospheric  currents.  These  admit  of  division  into 
natural  and  mechanical, — -the  former  comprehending  the  various 
forms  of  chimney  draughts  ;  the  latter  all  those  various  applica- 
tions of  compressive  means  which  will  be  presently  set  forth  in 
detail.  The  action  of  chimney  draughts  is  immediately  referable 
to  and  dependent  upon  the  circumstance  that  atmospheric  air,  like 
all  other  gases  and  most  other  bodies  of  whatever  cohesive  state, 
is  expanded  and  rendered  specifically  lighter  by  heat.  Thousands 
of  examples  of  this  result  continually  present  themselves,  from 
which  we  shall  select  a  few  prominent  illustrations.  An  illustra- 
tion of  the  diminution  of  specific  gravity  of  a  gaseous  mixture,  is 
furnished  by  the  blowing  of  soap-bubbles.  The  function  of  respi- 
ration causes  a  portion  of  the  air  taken  into  the  lungs  by  the  act 
of  breathing  to  be  robbed  of  its  oxygen,  which,  by  combining  with 
the  carbon  of  the  blood,  forms  carbonic  acid,  and  is  in  this  state 
of  combination  expired.  Seeing,  then,  that  the  air  expired  from 
the  lungs  is  not  pure  atmospheric  air,  but  a  mixture  of  the  latter 
with  nitrogen,  carbonic  acid,  and  aqueous  vapors,  it  follows  that 
the  specific  gravity  of  the  gaseous  material  expired  is  heavier  (at 
equal  temperatures)  than  that  of  the  unchanged  atmospheric  air. 
Although,  then,  a  soap-bubble,  blown  with  warm  air  from  the 
lungs,  rises,  this  rising  cannot  depend  on  any  quality  of  diminished 
specific  gravity  as  a  function  of  the  gaseous  matter  wherewith  they 
are  filled,  inasmuch  as  we  have  seen  the  latter  to  be  specifically 
heavier  by  the  amount  of  carbonic  acid  present.  It  depends  on 
the  circumstance  that  the  gaseous  materials  are  expanded  by  heat, 
owing  their  increased  lightness  to  that  cause.  Hence  it  is  that, 
although  for  a  time  the  bubbles  ascend, 
their  ascension  is  not  continuous — as  would 
have  been  the  case  had  they  been  filled  with 
hydrogen  gas — but  oflly  temporary.  As 
soon  as  their  gaseous  contents  become 
cooled  to  such  a  degree  that  they  are  spe- 
cifically heavier  than  the  external  air,  they 
descend. 

An   instructive  toy,  demonstrating    the 
ascensive  tendency  of  heated  air,  is  rep- 
resented  in   Fig.   5.      A   circular  disc  of 
Fig  5>  card-board  being  cut,  a  piece  of  thread  is 

attached  to  the  centre  ;  and  being  fixed  to 
a  hook,  the  card  is  suspended  from  a  fixed  support.    Thus  treated, 


SPECIAL    METALLURGIC   OPERATIONS.  51 

the  cut  card  unravels,  and  becomes  a  conoidal  screw  helix,  sus- 
ceptible of  rotation  when  an  upward  force  is  applied. 

If  now  any  small  source  of  flame  be  placed  underneath,  the 
helix  will  rotate,  thus  demonstrating  the  agency  of  an  upward 
force,  which  evidently  is  that  of  air  ascending,  on  account  of  the 
diminished  specific  gravity  referable  to  expansion  by  heat.  On 
precisely  similar  principles  is  constructed  the\  smoke-jack,  as  it  is 
called, — an  instrument  whose  rotation  is  totally  independent  of 
smoke,  and  is  altogether  referable  to  the  ascensive  force  resulting 
from  the  expansion  of  atmospheric  air.  Manifested  in  a  different 
way,  though  referable  to  the  same  primary  cause,  is  the  force 
which  causes  the  ascent  of  a  mongolfier  or  fire-balloon. 

Chimney-draught  is  a  natural  and  very  obvious  consequence  of 
the  expansion  of  air  by  heat,  to  which  our  attention  has  been 
directed.  The  combustible  materials  cannot,  as  is  well  known, 
burn  without  the  contact  of  air.  Part  of  the  air  concerned  is  sepa- 
rated into  its  constituents, — one  part  of  oxygen  uniting  with  car- 
bon to  form  carbonic  acid ;  another  part  with  hydrogen  to  generate 
water :  a  final  portion  of  air  remaining  undecomposed,  and  es- 
caping as  it  went  in.  Whatever  the  gaseous  or  vaporous  con- 
stituents which  escape  from  burning  materials  may  be,  they  are 
heated  by  the  fire  to  which  they  have  been  exposed,  and  are  for 
that  reason  expanded.  Hence  they  have  become  specifically  lighter, 
and  ascend,  leaving  a  partial  vacuum  in  the  chimney  or  shaft,  to  be 
made  good  by  a  further  flow  of  atmospheric  air,  or,  more  properly 
speaking,  the  gaseous  results  of  its  decomposition.  A  considera- 
tion of  the  principles  on  which  the  draught  of  a  chimney  depends, 
will  render  manifest  the  fact  that  a  chimney  may  be  too  long  for 
the  most  complete  activity  of  which  a  chimney  is  susceptible.  If 
it  be  so  tall  that  the  upward  currents  of  air  have  time  to.  cool  until 
its  specific  gravity  becomes  lower  than  the  specific  gravity  of  the 
external  air,  or  even  coincident  with  it,  the  practical,  no  less  than 
the  theoretical,  length  has  been  exceeded.  It  will  be  evident, 
moreover,  that  in  order  to  obtain  the  maximum  heat  for  any  given 
fuel  of  which  a  furnace  is  susceptible,  no  more  air  should  be 
albwed  to  permeate  the  burning  materials  than  the  amount  abso- 
lutely necessary  to  promote  the  highest  rate  of  combustion.  Any 
amount  of  passing  air  in  excess  of  this  theoretical  quantity,  what- 
ever it  may  be,  acts  as  a  cooling  agent ;  and  instead  of  augmenting 
the  power  of  combustion,  diminishes  it. 

All  furnaces  which  rely  on  mere  chimney-draught  for  determining 
the  passage  of  atmospheric  air  through  the  materials  of  combus- 
tion, are  under  the  necessity  of  sacrificing  a  portion  of  fuel  to  the 
object  of  producing  the  necessary  flow  of  air;  hence  for  the  greater 
number  of  operations  requiring  a  very  intense  heat,  chimney  - 
draught  as  a  means  of  effecting  aerial  transfusion  is  dispensed 
with  iu  favor  of  some  form  of  blast.  There  are  some  purposes 
however,  for  which  the  application  of  a  blast,  in  the  ordinary  sense 
of  the  term,  would  be  inconvenient;  in  which  a  cliimney-drangl  t, 


52  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

must  be  relied  upon  to  some  extent ;  its  power  being  increased  by 
some  collateral  means.  Iron  tubular  chimneys  do  not  answer  well, 
because  of  the  rapidity  wherewith  heat  is  lost  through  this  sub- 
stance, and  the  specific  gravity  of  the  gaseous  matter  which  they 
pour  forth  diminished.  Nevertheless  iron  or  at  least  metallic 
chimneys  are  a  necessity  in  the  case  of  steam-vessels  and  locomo- 
tive carriages.  Neither  one  nor  the  other  can  dispense,  therefore, 
with  a  powerful  draught,  which  is  accomplished  by  the  upward 
pressure  of  a  steam -jet. 

The  effect  of  this  liberation  is  to  drive  a  column  of  atmospheric 
air  violently  before  it,  thus  compensating  not  alone  for  the  cooling 
tendency  of  the  materials  of  the  chimney,  but  for  the  inadequate 
height  to  which  the  chimney  itself  is  limited  by  the  necessities  of 
steam-ships  and  locomotive-carriages. 

The  pressure  of  steam  applied  as  above-mentioned  is  very  great. 
Perhaps  considered  as  a  means  of  air  propulsion,  without  regard 
to  the  moisture  imparted,  there  is  no  method  of  producing  a  blast 
equally  effective.  Necessarily,  however,  the  steam  must  impart 
moisture  to  the  air,  thereby  deteriorating  the  latter  for  all  com- 
bustive  operations. 

BLAST-MACHINES. — The  most  primitive  method  of  generating 
an  air-blast  is  by  some  modification  of  the  leather  bellows.  Orig- 
inally bellows  were  nothing  more  than  the  skin  of  an  animal 
closely  sewn  except  at  one  part,  to  which  a  spout  or  delivery-tube 
was  attached,  also  serving  to  admit  a  further  charge  of  air  when 
the  sides  of  the  bag  were  pulled  asunder.  From  this  primitive 
instrument  to  the  valved  single  bellows,  and  thence  to  the  valved 
double  bellows,  used  at  this  time  by  blacksmiths,  and  yielding  an 
uninterrupted  stream,  the  transition  is  obvious.  The  great  ad 
vantages  of  bellows  are  economy  of  first  cost,  and  facility  of  em- 
ployment. They  serve  perfectly  well  for  blacksmiths'  forges  and 
small  furnaces ;  but  the  use  of  bellows  in  metallurgic  operations 
on  the  large  scale  is  limited,  and  gradually  decreasing. 

The  blowing  apparatus  now  generally  employed  on  the  large 
scale  is  that  of  compression  cylinders.  It  is  obvious  that  a  metallic 
cylinder,  like  the  cylinder  of  a  steam-engine,  may  be  converted 
by  a  simple  arrangement  of  valves  and  piston  work  into  a  power- 
ful apparatus  for  delivering  compressed  air.  An  usual  form  of 
compression  cylinder  is  represented  in  Fig.  6. 

The  effective  power  of  a  blowing  cylinder — or,  in  other  words, 
the  quantity  of  air  of  specified  density  which  it  contributes  in  a 
given  time,  may  be  arrived  at  in  two  distinct  ways.  The  first  con- 
sists in  ascertaining  the  actual  capability  of  the  cylinder,  and  de- 
termining the  number  of  times  it  can  be  filled  with  air  and  the  air 
discharged  in  a  given  time.  The  second  method  is  by  ascertaining 
the  velocity  or  power  of  the  first,  determined  by  taking  into  con- 
sideration the  circumstances  of  barometric  pressure,  moisture,  and 
temperature  at  the  time  of  the  experiment.  , 

As  regards  the  former  method  of  investigation,  it  must  be  borne 


SPECIAL   METALLURGIC  OPERATIONS. 


53 


in  mind,  that  the  number  of  times  per  minute,  or  for  any  other 
given  period,  that  a  blowing  cylinder  is  filled,  would  be  a  very 


Fig.  6. 


false  criterion  of  the  actual  amount  of  air  which  finds  its  way  into 
the  furnace.  Owing  to  the  elasticity  of  the  air,  ineffective  space 
in  the  cylinder,  loss  of  air  between  the  cylinder  and  piston,  added 
to  further  losses  in  the  windways  and  regulators,  the  actual  amount 
of  air  which  finds  its  way  into  the  furnace  is  always  some  20  or 
even  25  per  cent,  less  than  the  total  amount  subjected  to  compres- 
sion. This  loss  occurs  even  in  the  best  blowing  cylinders.  In 
wooden  blowing-chests — a  common  form  of  apparatus — the  loss 
not  unfrequently  amounts  to  nearly  double.  Being  aware  of  the 
loss  incurred,  the  appended  formula  may  prove  serviceable.  It 
teaches  the  amount  of  air  of  natural  atmospheric  density  taken 
into  a  blowing  cylinder  in  one  minute  of  time. 


Q 


9* .  *  .  h     60 
4  d 

in  which 

Q  represents  the  amount  of  atmospheric  air  sought — in  cubic 
feet. 

g  the  diameter  of  the  piston  in  feet. 

ft  ratio  of  circumference  to  diameter  (»'.  e.  the  number  8.1515). 

h  length  of  piston-stroke  expressed  in  feot. 

d  number  of  revolutions  expressed  in  terms  of  seconds. 

Though  compression-cylinders  furnish  the  most  powerful  and 
the  most  certain  means  of  delivering  air  in  a  blast,  there  are  others 
of  great  practical  importance.  The  ventilator  or  fan-blast  is  one 
of  the  most  useful,  and  at  the  same  time  most  simple.  It  is  repre- 


54  THE  PKACTICAL   METAL-WORKER'S  ASSISTANT. 

sented  in  the  two  following  diagrams  sectionally.     Fig.  7  repre- 
sents a  cylinder  or  drum,  cut  transversely  to  its  axis,  and  display- 


Fig.  7. 


Fig.  8. 


ing  the  sectional  view  of  four  vanes.  Fig.  8  represents  the  same 
cylinder  cut  parallel  to  its  axis,  and  displaying  two  central  open- 
ings, one  on  each  side. 

When  the  vane  is  put  in  motion,  air  enters  by  the  central  aper- 
tures, and  is  forcibly  and  continuously  driven  out  through  the 
aperture,  thus  constituting  the  blast.  This  form  of  apparatus  has 
been  so  familiarized  by  being  substituted  for  domestic  bellows, 
that  its  description  is  almost  unnecessary. 

Notwithstanding  the  disadvantages,  practical  no  less  than  theo- 
retical, which  attach  to  the  employment  of  moist  air  in  furnace 
operations,  hydraulic  blasts  of  simple  description  are  amongst  the 
most  ancient;  whilst  modern  variations  on  the  principle  of  hy- 
draulic blowing  have  given  rise  to  some  simple  and  curious 
machines. 

The  trompe,  as  it  is  called,  is  a  simple  and  ingenious  method  of 
determining  a  current  of  wind  by  a  falling  current  of  water.  It 
is  a  form  of  apparatus  very  prevalent  in  Catalonia:  hence  the  ap- 
pellation "Catalan  trompe,"  which  is  sometimes  applied  to  it.  The 
instrument,  however,  slightly  modified,  is  employed  in  Italy  and 
Switzerland,  being  applicable  to  mountainous  regions  where  high 
falls  of  water  can  be  commanded,  and  the  amount  of  atmospheric 
pressure  required  is  inconsiderable. 

An  examination  of  the  accompanying  figure  will  render  evident 
the  construction  and  principles  on  which  the  trompe  is  founded. 

The  diagram  (Fig.  9)  represents  a  cistern  above,  containing 
water,  and  communicating  with  the  vertical  pipes  which  respec- 
tively terminate  in  two  chests.  Between  these  chests,  and  placing 
them  in  aerial  connection,  is  a  semicircular  pipe ;  and  the  part  of 


SPECIAL   METALLURGIC   OPERATIONS. 


the  apparatus  on  the  left,  sectionally  represented,  shows  a  trans- 
verse plank,  on  which  the  water 
is  broken  in  its  fall.  The  action , 
of  the  trompe  is  this  :  The  verti- 
cal column  of  water,  in  its  de- 
scent, carries  before  it,  and  min- 
gled with  it,  considerable  por- 
tions of  atmospheric  air  :  striking 
against*  the  transverse  plank,  a 
separation  between  the  air  and 
water  is  effected,  the  former  pass- 
ing into  the  arched  tube  and  es; 
caping  as  a  blast  through  a  tubu- 
lar orifice  corresponding  with  0, 
whilst  the  water  passes  into  the 
lower  reservoir.  This  form  of 
apparatus  would  be  quite  inopera- 
tive if  applied  to  furnaces  heated 
with  coke  or  coal;  but  it  answers 
sufficiently  well  in  cases  where! 
charcoal  is  the  fuel  employed. 
CHAIN  BLAST. — This  is  a  some-  J 

what  elaborate  application  of  hy-  [ 

draulic  laws  to  the  purpose  of  Fig.  9. 

creating  an  air-blast.  It  is  depicted  in  the  accompanying  dia- 
gram (Fig.  10),  and  its  con- 
struction is  as  follows  :  An 
endless  chain,  furnished  with 
certain  appendages,  the  mo- 
tive of  which  we  shall  pres- 
ently explain,  is  seen  to  pass 
over  a  wheel  or  pulley,  and 
through  a  pipe  which  termi- 
nates in  an  air-chamber  below. 
This  air-chamber  communi-  fj. 
oates  with  a  bent  tube,  as  rep- 
resented :  and  a  lateral  tube 
pointing  towards  the  left  is 
also  seen  to  be  connected  with 
the  upper  part  of  the  vertical 
tubular  shaft.  Glancing,  now, 
at  the  transverse  appendages 
to  the  endless  chain,  placed  at 
regular  intervals  throughout 
its  length,  they  consist  of 
cylindrical  boxes  quite  open 
at  one  end,  and  capable  of 
being  opened  or  shut  at  the 
other  end,  each  by  two  flaps  Fig.  10. 


56  THE   PEACTICAL   METAL-WORKEll's   ASSISTANT. 

or  valves.  The  latter  fall  by  their  own  weight  when  the  cylinders 
are  on  the  left,  or,  as  will  be  hereafter  seen,  at  every  part  of  their 
downward  descent,  and  open  (as  represented  in  the  diagram)  when 
moving  upwards.  When  it  is  now  explained  that  water  enters  by 
the  lateral  orifice  /,  the  action  of  the  machine  will  be  made  evi- 
dent. The  water  pressing  successively  on  each  cylinder,  causes  it 
to  descend  through  the  vertical  pipe,  conveying  with  it  the  air  with 
Avhich  it  is  filled,  and  which  cannot  escape,  because  the  valves  are 
shut.  Each  cylinder,  therefore,  liberates  its  contents  of  "Sir  into 
the  air-chamber  below,  and  thence  through  the  associated  blast- 
tube.  Passing  on,  the  valve  side  of  each  cylinder  again  looks 
downwards,  and  the  valves  open,  only  to  shut  once  more,  and  to 
act  as  before  described,  so  soon  as  they  again  take  their  downward 
course. 

A  still  more  powerful  and  not  less  ingenious  method  of  creating 
a  hydrostatic  blast,  is  furnished  by  the  machine  known  in  Europe 
by  the  name  of  "  Cagniardelk."  This  instrument  may  be  generally 
described  as  consisting  pf  a  cylindrical  screw,  'the  shaft  of  which 
fits  air-tight  to  a  cylinder  in  which  it  is  inclosed, — the  cylinder 
•being  diagonally  placed  in  a  reservoir  partially  filled  with  water 
(Fig.  11).  - 


Fig.  11. 


One  end  of  the  cylinder  is  seen  to  be  flat,  the  other  conoidal. 
Through  the  truncated  apex  of  the  conoid  a  deli  very -pipe  is  also 
seen  to  pass ;  but  the  diagram  does  not  represent  what  is  actually 
the  fact,  that  the  flat  end  of  the  cylinder  is  open.  It  follows  as  a 
necessity  of  the  construction  of  this  instrument,  that  the  atmos- 
pheric air  which  enters  by  the  open  flat  end  is  screwed  along  by 
the  combined  force  of  rotation  and  water-pressure  until  it  reaches 
the  tube  passing  through  the  truncated  apex,  which  tube  is  a  de- 
livery tube  for  air. 


V 

RECENTLY   PATENTED   REFINING   PROCESSES.  57 

CHAPTER  III. 

RECENTLY  PATENTED   REFINING   PROCESSES. 

WE  now  come  to  deal  with  a  class  of  metallurgic  processes 
which  have  recently  much  occupied  the  public  attention — an  at- 
tention which  their  importance  fully  justifies.  We  allude,  of 
course,  to  the  processes  patented  or  otherwise  having  for  object 
the  conversion  of  ordinary  cast-iron  into  malleable  iron,  by  the 
application  of  air,  or  air  and  steam  combined,  without  the  inter- 
vention of  fuel.  We  cannot  but  regret  that  necessity  compels  us 
to  take  up  the  subject  in  its  present  unsettled  state,  as  we  hoped 
to  have  communicated  more  exact  information  on  these  important 
inventions  than  is  at  present  attainable. 

The  processes  by  which  iron  has  hitherto  been  converted,  are 
of  the  most  laborious  character ;  more  especially,  when  the  gigan- 
tic efforts  required  on  the  part  of  the  workmen  in  the  puddling 
and  refining  processes  are  considered ;  and  it  is  difficult  to  over- 
estimate the  importance  of  any  discovery  by  which  even  a  portion 
of  this  laborious  operation  can  be  dispensed  with.  Nor  when  the 
economical  considerations  which  enter  into  the  question  are  borne 
in  mind,  will  it  surprise  the  reader  that  the  change  in  the  iron 
manufacture,  which  it  was  presumed  would  at  once  follow  the  an- 
nouncement of  Mr.  Bessemer's  discovery,  should  have  created  an 
excitement  almost  amounting  to  a  panic  in  the  principal  iron  dis- 
tricts. It  was  not  in  the  nature  of  things,  however,  that  such 
startling  and  rapid  changes  should  at  once  develop  themselves  in 
perfection.  The  process,  therefore,  although  watched  with  much 
interest  by  those  interested,  is  at  present  only  felt  to  be  a  step  in 
advance  of  the  older  processes,  which  will  be  welcomely  received, 
should  the  experiments  now  preparing  on  a  large  scale  fulfil  the 
expectations  entertained  of  it.  The  inventions  to  which  we  have 
alluded  we  shall  take  in  their  chronological  order,  beginning  with 
the  earliest  of  them,  namely : 

MR.  PLANT'S  PROCESS. — Of  thiS  process  no  specification  has  been 
published.  We  must,  therefore,  avail  ourselves  of  the  condensed 
report  given  of  it  in  the  "  London  Journal  of  Arts."  The  patent 
is  dated  July  18,  1849.  In  it  the  patentee  claims  to  have  made  an 
improvement  in  making  bar-iron  by  the  use  of  either  hot  or  cold 
blasts,  with  steam-jets  and  atmospheric  air,  or  with  steam-jets  by 
themselves,  to  be  used  in  regulating  the  heat  in  the  puddling- 
chambers,  either  with  the  ordinary  damper  in  the  draught  of  the 
chimney,  or  with  a  special  damper  and  apparatus  adapted  to  his 
invention. 

This  apparatus  consists  of  a  puddling-furnace  of  ordinary  di- 
mensions, having  three  lines  of  tuyeres  across  the  top  of  the  fur- 
nace, each  line  consisting  of  three  tuyeres  one  inch  in  diameter, — 


58  THE   PRACTICAL   METAL-WOEKER's   ASSISTANT. 

the  line  furthest  from  the  chimney  being  for  the  blast,  the  other 
two  being  steam-tuyeres  for  the  puddling  and  preparatory  cham- 
bers. The  blast-tuyeres  are  to  be  capable  of  a  pressure  of  one 
pound  and  upwards  to  the  square  inch ;  the  steam  to  be  used  at  a 
pressure  of  ten  pounds  and  upwards. 

The  blast  is  to  be  introduced  at  the  top  of  the  puddling- chamber, 
in  a  slanting  direction,  just  behind  the  fire-bridge,  so  as  to  draw 
the  flame  down  upon  the  whole  surface  of  the  metal  as  it  enters 
the  puddling-chamber;  the  steam  being  introduced  as  nearly  as 
possible  at  the  same  spot,  and  thrown  in  like  manner  upon  the 
whole  metal. 

By  these  means,  it  is  stated,  the  heat  of  the  furnace  and  pre- 
paratory-chambers can  be  regulated  with  great  nicety,  without  em- 
ploying the  damper  usually  inserted  in  the  chimney  of  a  puddling- 
lurnace.  When  the  metal  is  melted,  the  blast  is  shut  oft',  and  steam 
introduced  through  the  tuyeres  until  the  iron  boils ;  the  steam  is 
then  turned  off  and  the  blast  brought  into  action  till  the  iron  ap- 
pears above  the  cinder,  when  the  blast  is  again  shut  off  and  the 
iron  finished  in  the  usual  manner  by  the  ordinary  draught.  The 
heat  of  the  puddling-chamber  is  raised  or  lowered  from  time  to 
time  by  raising  or  lowering  the  damper  over  the  fire-bridge. 

In  this  process,  a  greater  separation  of  the  metal  is  caused,  it  is 
presumed,  by  the  blast  of  air  and  jets  of  steam  thrown  upon  the 
metal;  and  the  carbon  and  other  impurities  are  supposed  to  be 
more  thoro.ughly  removed  by  the  infusion  of  the  oxygen  of  the 
atmosphere. 

MARTIEX'S  PROCESS,  to  which  we  shall  now  call  attention,  is  that 
patented  by  Joseph  Grille*  Martien,  of  Newark,  New  Jersey,  in 
September,  1855,  and  has  for  its  object  the  purification  of  iron  when 
in  the  molten  state  from  the  blast  or  refining-furnace,  either  by  air 
or  steam,  or  vapor  of  water  applied  from  below,  so  that  it  may 
rise  up  amongst,  and  completely  penetrate  and  search  every  part 
of  the  metal  previous  to  congelation,  and  prior  to  its  being  run 
into  a  reverberatory-furnace  for  puddling.  By  this  means  the 
manufacture  of  wrought-iron  by  puddling,  and  the  manufacture  of 
steel  from  cast-iron  in  the  ordinary  manner,  are  stated  to  be  greatly 
improved.  * 

In  carrying  out  his  invention,  Mr.  Martien  employs  channels,  or 
gutters,  so  arranged  that  the  numerous  streams  of  air,  of  steam,  or 
of  vapor  of  water,  are  passed  through  and  amongst  the  melted 
metal,  as  it  flows  from  the  blast-furnace.  This  is  done  by  subjecting 
the  metal  to  the  action  of  streams  of  air  or  steam,  as  it  passes  from 
the  blast-furnace  before  it  congeals.  The  apparatus  recommended, 
consists  of  cast-iron  channels  or  gutters,  having  the  bottom  made 
hollow  to  receive  steam  or  air,  or  both.  This  gutter  is  perforated 
with  numerous  holes,  obliquely  inclined  in  the  direction  of  the 
flowing  metal,  so  that  the  streams  of  air  or  steam  may  be  forced 
through  it  as  it  flows  along  the  gutter.  The  stream  of  air,  however, 
may  also  be  passed  up  through  the  metal ;  or  the  holes  may  be  in- 


RECENTLY   PATENTED   REFINING   PROCESSES.  59 

clined  in  the  opposite  direction,  so  as  to  oppose  the  flow  of  the 
molten  metal.  When  the  hot  or  cold-blast  is  used,  the  hollow 
bottom  of  the  gutter  may  be  connected  with  the  air-pipes  used  for 
supplying  the  blast ;  or,  when  steam  is  employed,  the  gutter  may 
be  connected  with  the  boiler.  By  these  means,  the  air  or  steam  in- 
troduced rises  up  through  the  metal  in  numerous  streams,  and  the 
iron  is  stated  to  be  perfectly  purified  after  it  has  come  from  the 
blast-furnace,  and  before  congelation  takes  place.  The  iron  thus 
purified  may  be  allowed  to  cool  in  the  mould,  or  it  may  run  from 
the  gutter  into  a  reverberatory  or  other  refining  furnace,  to  be 
heated  and  puddled  in  the  usual  manner.  In  this  process,  the 
novelty  claimed  is  that  of  purifying  iron  from  a  blast-furnace  while 
still  in  a  molten  state,  without  the  intervention  of  fuel ;  thus  pre- 
paring it  for  the  puddling  process  in  a  state  of  greater  perfection 
than  by  the  old  process.  The  perceptive  faculties  of  James 
Nasmyth,  to  use  the  words  of  Mr.  Bridges  Adams,  the  eminent 
civil  engineer,  "detected  the  absurdity  of  setting  a  number  of 
human  beings  to  stir  up  a  metallic  puddling  in  order  to  throw  off 
the  scum  in  the  shape  of  slag  or  cinder.  His  remedy  was  a  me- 
chanical one — to  cause  the  mass  to  boil  like  a  pot,  by  forcing  steam 
into  it  from  below,  the  issue  of  steam  beginning  before  the  molten 
mass  was  poured  in,  so  as  to  insure  against  the  stoppage  of  the 
passages.  But  steam  is  not  exactly  fuel,  and,  instead  of  increasing, 
tends  to  lower  the  temperature  of  the  mass  of  iron." 

MR.  CLAY'S  PROCESS. — Among  other  ingenious  inventions,  we 
may  here  mention  that  of  Mr.  Clay  of  the  Mersey  Iron  "Works, — an 
invention  for  which  a  patent  was  taken  out  and  a  specification  lodged, 
as  applicable  both  to  malleable  iron  and  cast  steel ;  although  all 
claim  for  the  latter  purpose  has  since  been  withdrawn  in  favor  of 
Captain  Uchatius's  process.  Mr.  Clay  proposes  to  refine  the  crude 
iron  by  a  process  of  granulation,  produced  by  dropping  iron  in  a 
molten  state  from  a  lofty  tower  into  a  water-tank,  after  the  manner 
in  which  small  lead-shot  is  cast.  In  this  process,  he  states  that  the 
highly  separated  metal  is  purified  by  contact  with  the  air  in  its 
lengthened  descent,  and  by  the  chemical  change  produced  by  im- 
mersion in  the  water,  so  that,  when  again  melted  for  the  puddling 
furnace,  it  is  divested  of  most  of  the  impurities  of  crude  iron. 

For  the  purposes  of  this  invention,  iron  may  be  obtained  either 
from  the  blast-furnace,  from  which  it  may  be  run  out  in  a  molten 
state,  or  it  may  be  melted  down  from  pig  or  scrap  cast-iron.  The 
granulation  of  the  iron  is  effected  by  causing  the  metal,  when  in  a 
molten  state,  to  run  through  a  perforated  plate  of  metal  or  other 
material,  placed  at  the  top  of  a  tower-shaft  or  well ;  by  this  means 
it  will  be  divided  into  small  shot-like  particles.  In  its  descent  in 
this  state  from  a  suitable  height,  varying  according  to  the  nature 
and  quality  of  the  iron  operated  upon,  the  metal  will,  during  its 
passage  through  the  air,  be  partially  decarbonized,  inasmuch  as  the 
oxygen  of  ordinary  atmospheric  air  acts  with  considerable  force  in 
decarbonizing  the  metal  as  it  falls  through  it ;  it  will  thus  be  ren- 


60  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

dered  more  suitable  for  working  up  by  puddling  into  malleable 
bar-iron. 

It  is  sometimes  advisable  to  charge  the  air  in  the  shaft,  through 
which  the  molten  metal  is  to  pass,  with  artificially  prepared  oxygen, 
or  with  some  other  decarbonizing  gas  or  vapor,  which  will  produce 
a  more  vigorous  decarbonizing  action  upon  the  iron.  This  may 
be  effected  by  the  decomposition  of  the  salts  of  potash,  such  as 
chlorate  of  potash,  or  nitrate  of  potash,  both  of  which  contain  con- 
siderable quantities  of  oxygen;  and  their  decomposition  may  be 
effected  either  by  dropping  the  red-hot  metal,  in  a  granulated  or 
finely-divided  state,  upon  a  bed  of  the  salts  of  potash,  or  by  heating 
the  salts  in  a  retort  until  oxygen  is  given  out.  Other  "minerals, 
also,  such  as  manganese,  may  be  employed,  either  alone  or  in  com- 
bination with  other  substances,  as  oxygenating  agents.  The  pat- 
entee also  employs  the  more  simple  means  of  increasing  the 
oxygenizing  powers  of  atmospheric  air,  by  introducing  a  blast  or 
draught  of  air,  either  hot  or  cold,  as  may  be  found  most  effective, 
into  the  tower  down  which  the  iron  is  descending.  Dry  steam  may 
also  be  applied  to  effect  the  object  in  view. 

Mr.  Clay  has  found  that  by  allowing  the  molten  metal  to  fall 
through  the  air  a  distance  of  about  seventy  feet,  a  satisfactory  result 
has  been  obtained ;  this,  however,  depends  both  upon  the  quality 
of  the  iron  and  upon  the  state  of  preparation  in  the  shaft.  With  at- 
mospheric air  at  the  ordinary  pressure,  the  metal  requires  to  fall 
through  a  greater  distance,  than  if  charged  with  the  artificial  means 
above  referred  to.  The  granulated  particles  of  molten  iron  may 
either  fall  into  water  at  the  bottom  of  the  tower  or  well,  or  they 
may  be  collected  in  a  vessel  or  reservoir  placed  for  the  purpose. 

The  decarbonized  metal  thus  obtained,  it  is  scarcely  necessary 
to  add,  is  collected  together  and  remelted  into  ingots  or  bars,  pre- 
paratory to  undergoing  the  ordinary  treatment  of  hammering  and 
rolling. 

MR.  BESSEMER'S  PROCESS. — We  have  now  to  speak  of  that  pro- 
cess of  Mr.  Bessemer's,  which  has  arrested  so  much  attention,  even 
of  the  ordinary  reader,  in  the  last  few  months.  Mr.  Bessemer's  first 
patent  is  dated  January  4,  1856.  Others  he  has  since  taken  out 
bearing  date  February  12,  May  15  and  31,  1856.  To  the  most  com- 
plete of  these,  namely,  that  of  February  12,  1856,  we  shall  direct 
our  attention.  In  the  specification  now  before  us  the  invention 
is  said  to  consist  in  the  decarbonization  and  refinement,  in  whole 
or  part,  of  the  crude  iron,  which  is  either  obtained  in  a  fluid  state 
from  the  furnaces  in  which  the  iron  ore  has  been  reduced,  or  in  the 
decarbonization  and  refinement  of  crude  pig  or  finery  iron,  by  re- 
melting  the  pigs  in  a  suitable  furnace  so  as  to  obtain  fluid  metal 
capable  of  being  treated  by  the  process  we  are  about  to  describe. 
This  consists,  firstly,  in  running  the  fluid  iron  from  the  furnace 
into  a  close  or  nearly  close  vessel  or  chamber,  formed  of  iron,  per- 
forated with  openings  to  receive  the  tuyeres,  and  lined  with  fire- 
brick or  other  material  which  is  a  slow  conductor  of  heat.  When 


RECENTLY  PATENTED   REFINING   PROCESSES.  61 

this  vessel  is  almost  half  filled,  numerous  small  jets  of  atmospheric 
air,  or  gaseous  matter  capable  of  evolvin%  sufficient  oxygen  to 
cause  combustion  of  the  carbon  of  the  iron,  are  forced  into  and 
among  the  fluid  metal,  either  in  a  cold  or  previously  heated  state. 
"  Atmospheric  air  or  oxygen  is  thus  introduced  into  the  metal,  in 
sufficient  quantities  to  produce  a  vivid  combustion  among  the 
particles  of  the  fluid  metal;  and  to  retain  and  increase  its  temperature 
to  such  a  degree,  that  the  metal  will  continue  fluid  during  its 
transition  state  from  "crude  iron  to  that  of  cast  steel  or  malleable 
iron  without  the  application  of  fuel." 

Mr.  Bessemer  stated  in  the  paper  with  which  he  ushered  his  in- 
vention to  the  British  Association,  that  for  the  last  two  years  his 
attention  had  been  almost  exclusively  directed  to  the  manufacture 
of  malleable  iron  and  steel,  in  which,  however,  he  had  made  but 
little  progress  until  within  the  last  eight  or  nine  months.  The 
constant  pulling  down  and  rebuilding  of  furnaces,  and  the  toil  of 
daily  experiments  with  large  charges  of  iron,  had  already  begun 
to  exhaust  his  stock  of  patience ;  but  the  numerous  observations 
made  during  this  very  unpromising  period  all  tended  to  confirm  an 
entirely  new  view  of  the  subject,  which  at  that  time  forced  itself 
upon  his  attention — viz.,  that  he  could  produce  a  much  more  intense 
heat  without  any  furnace  or  fuel,  than  could  be  obtained  by  either 
of  the  modifications  hitherto  used,  and  consequently  not  only  avoid 
the  injurious  action  of  mineral  fuel  on  the  iron  under  operation, 
but  at  the  same  time  avoid  the  expense  of  the  fuel.  Some  prelim- 
inary trials  were  made  on  from  10  Ib.  to  20  Ib.  of  iron,  and,  although 
the  process  was  fraught  with  considerable  difficulty,  it  exhibited 
such  unmistakable  signs  of  success  as  to  induce  him  at  once  to  put 
up  an  apparatus  capable  of  converting  about  7  cwt.  of  crude  pig- 
iron  into  malleable  iron  in  thirty  minutes.  With  such  masses  of 
metal  to  operate  on,  the  difficulties  which  beset  the  smaller  experi- 
ments entirely  disappeared.  On  this  new  field  of  inquiry,  he  set 
out  with  the  assumption  that  crude  iron  contains  about  five  per 
cent,  of  carbon ;  that  carbon  cannot  exist  at  a  white  heat  in  the 
presence  of  oxygen  without  uniting  therewith  and  producing  com- 
bustion ;  that  such  combustion  would  proceed  with  a  rapidity  de- 
pendent on  the  amount  of  surface  of  carbon  exposed :  and,  lastly, 
that  the  temperature  which  the  metal  would  thus  acquire,  would  be 
also  dependent  on  the  rapidity  with  which  the  oxygen  and  carbon 
\vere  made  to  combine,  and  consequently  that  it  was  only  necessary 
to  bring  the  oxygen  and  carbon  together  in  such  a  manner  that  a 
vast  surface  should  be  exposed  to  their  mutual  action,  in  order  to 
pnx luce  a  temperature  hitherto  unattainable  in  our  largest  furnaces. 
With  a  view  of  testing  practically  this  theory,  he  constructed  a 
cylindrical  vessel  of  three  feet  in  diameter  and  five  feet  in  height, 
somewhat  like  an  ordinary  cupola  furnace,  the  interior  of  which 
was  lined  with  fire-bricks,  and  at  about  two  inches  from  the  bottom 
of  it  five  tuyere-pipes  were  inserted,  the  nozzles  of  which  were 
formed  of  well-burnt  fire-clay,  the  orifice  of  each  tuyere  being 


62 


THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 


about  three-eighths  oflan  inch  in  diameter ;  they  were  so  put  into 
the  bricklining  (from  the  outer  side)  as  to  admit  of_  their  removal 
and  renewal  in  a  few  minutes  when  they  were  worn  out.  At  one 
side  of  the  vessel,  about  half  way  up  from  the  bottom,  there  is  a 
hole  made  for  running  in  the  crude  metal ;  and  on  the  opposite  side 
there  is  a  tap-hole  stopped  with  loam,  by  means  of  which  the  iron 
is  run  out  at  the  end  of  the  process. 

The  apparatus  by  which  it  is  now  proposed  to  carry  out  this 
process,  differs  somewhat  from  that  described  above :  it  is  a  cylin- 
drical vessel,  mounted  on  axes  not  placed  at  the  centre  of  gravity. 
Of  this  vessel,  Fig.  12  is  an  end  elevation.  The  vessel  is  formed  of 


Fig.  12. 


stout  plates,  secured  by  angular  iron  flanges  to  the  cast-iron  plates  a', 
strengthened  by  webs  or  ribs  of  iron,  c  c  are  iron  frames  secured 
by  bolts  d  to  the  masonry,  or  foundation  on  which  the  operation 
rests.  The  frame  c'  rises  higher  than  the  others,  and  has  plummer 
blocks  e  e  bolted  to  it,  on  which  the  shaft  /  revolves.  A  worm- 
wheel  g  is  keyed  firmly  on  to  the  axis  b,  and  receives  motion  from 
the  worm  h  when  moved  by  the  handle  i.  At  the  point  of  junc- 
tion of  two  of  the  webs  a,  will  be  seen  a  boss ;  into  this  boss  a 
stud  is  fixed,  to  which  a  chain,  or  tension-rod,  may  be  attached, 
suspended  over  a  pulley  from  the  roof,  for  supporting  a  counter- 
balance weight,  so  as  to  facilitate  the  movement  of  the  vessel  on 
its  axis,  and  assist  the  worm-wheel  gearing  y  h. 


RECENTLY   PATENTED   REFINING   PROCESSES. 


63 


The  intention  in  having  the  refining  vessel  thus  mounted  on 
axes,  is  the  convenience  it  offers  for  pouring  out  the  fluid  metal 
into  the  ingot-mould,  for  which  purpose"  it  is  furnished  with  a  lip 
or  spout,  which  is  placed  in  a  line  with  the  mould,  the  latter  being 
kept  in  a  proper  position  for  removing  the  fluid  contents.  The 
air,  or  other  gaseous  matters,  which  are  to  operate  on  the  metal, 
must  be  compressed  with  a  force  greater  than  will  balance  the 
weight  of  a  column  of  fluid  metal  of  a  height  equal  to  the  depth 
of  immersion  of  the  jets  below  the  surface  of  the  fluid  metal. 
This  air,  as  will  afterwards  be  shown,  is  introduced  at  the  sides  or 
ends  of  the  vessel,  through  small  holes  formed  in  the  fire-clay 
lining ;  so  that,  by  moving  the  chamber  on  its  axis,  the  holes  in 
the  fire-clay  may  be  made  to  descend  beneath  the  surface  of  the 
metal,  or  raised  above  it  as  may  be  desired. 

In  Fig.  13  is  represented  a  longitudinal  section  of  the  converting 
vessel,  in  order  to  give  a  more  correct  idea  of  its  construction. 


Fig.  13. 

The  section  presents,  at  one  side  of  a'  and  at  a  point  beyond  the 
outer  edges,  the  bosses  a',  which  are  bored  out  truly,  and  fitted  and 
keyed  to  the  axes  b  b ;  and  on  these  the  vessel  is  made  to  move 
when  turned  by  the  worm-gearing  g  h  (Fig.  12).  At  r  there  is  a 
pipe  which  communicates  either  with  a  blast-engine  or  steam- 
boiler,  or  it  may  be  made  to  communicate  with  a  reservoir  of 
oxygen  gas,  or  any  other  gaseous  matter  capable  of  evolving  oxy- 
gen, either  in  a  cold  or  heated  state.  The  pipe  r  is  fitted  to  one 
end  of  the  trunnion  or  axis  b,  which  is  hollow,  and  provided  with 
a  stuffing-box,  or  other  joint,  so  as  to  allow  of  the  movement  of 
the  axis  without  interring  with  the  passage  of  the  air  or  other 
matters  through  it.  This  pipe  is  continued  to  S,  and  along  the 
outside  of  the  vessel  S,  whore  it  requires  to  be  turned  truly  on  its 
exterior  surface,  having  fitted  to  it  several  small  branch-pipes  u, 


THE   PRACTICAL   MBTAL-WORKER'S   ASSISTANT. 


eacli  of  which  has  a  T  piece  connected  to  it,  which  is  bored  out 
truly,  so  as  accurately  to  fit  the  exterior  of  the  pipe  S;  thus  ad- 
mitting of  the  pipe  u  being  moved  on  the  pipe  S  into  its  proper 
position.  The  object  here,  is  to  connect  the  blast-engine  with  the 
converting  vessel,  along  one  side  of  which  there  is  a  row  of  square 
holes :  into  these,  small  blocks  of  well-burnt  fire-clay  are  closely 
fitted,  and  held  in  position  by  ramming  a  little  loam  into  the  joint 
formed  between  them  and  the  lining  m.  At  one  of  these  blocks 
or  tuyeres,  the  pipe  u  is  fitted  by  a  simple  cone  joint,  the  other 
ends  of  the  tuyere-blocks  having  several  small  perforations  leading 
into  one  larger  passage  communicating  with  the  pipes  u ;  a  com- 
munication is  thus  established  between  numerous  points  of  the 
interior  surface  of  the  converting  vessel  and  the  blast-engine  or 
other  apparatus  used.  A  sluice-cock  on  the  pipe  r,  enables  the 
workman  to  turn  this  off  or  on  as  required. 

The  manner  in  which  these  pipes  and  tuyeres  act  will  be  better 
understood  by  the  following  engravings,  where  Fig.  14  represents 

a  section  of  the  pipe 
u,  and  the  mode  of 
fitting  it  into  the 
pipe  S;  while  Fig.  15 
shows  them  in  their 
ordinary  working  po- 
sition. It  will  be  seen 
by  Fig.  14  that  the 
pipe  S  has  an  open- 
ing at  x  opposite  the 
orifice  of  the  pipe  u. 
When  these  pipes  oc- 
cupy their  ordinary 
position,  as  in  Fig. 
15,  the  air  passes 
freely  through  the 
opening ;  but  when 
the  tuyere-blocks  require  renewing,  the  pipe  u  can  be  turned  upon 
the  union  joint  formed  at  the  junction  x :  free  access  to  the  tuyere 
is  thus  obtained.  The  manner  in  which  these  pipes  act  upon  the 
metal  in  the  converting  vessel  is  shown  in  Fig.  16,  and  again  in 
Fig.  17. 

The  tuyere-blocks  may  be  formed  of  one  or  of  several  smaller 
apertures,  one  being  found  to  answer  perfectly  well  in  practice ; 
they  must,  however,  be  made  to  fit  exactly  into  the  pipe.  These 
passages  sometimes  get  obstructed.  To  provide  for  this,  a  screw- 
plug  (Fig.  14)  is  fitted  at  the  back  of  the  elbow  of  the  pipe  u, 
which  may  be  removed  if  necessary,  and  a  steel  rod  thrust  through 
the  aperture,  so  as  to  remove  any  accumulations  of  matter. 

The  interior  of  the  converting  vessel  itself  is  lined  with  fire- 
brick or  fire-stone,  as  shown  at  m  (Fig.  13) ;  and  arrangements  are 
made  by  which  this  lining  may  be  renewed  or  repaired  either  by 


Fig.  14. 


Fig.  15. 


RECENTLY   PATENTED   REFINING   PROCESSES. 


65 


removing  one  of  the  end  plates  a1,  which  can  be  bolted  on  again  ; 
or  a  man  -  hole 
may  be  devised 
in  the  side  of  the 
vessel  through 
which  the  lining 
may  be  repaired 
without  this  re- 
moval. The  pe- 
culiarities of  the 
vessel  itself  we 
shall  now  de- 
scribe ;  and  in 
order  to  convey 
a  correct  idea  of 
it,  we  give  two  il- 
lustrations (Figs. 
16  and  17):  one 
a  vertical  sec-  Fis- 16< 

tion,  exhibiting  the  vessel  while  the  metal  is  in  a  molten  state, 


Fig.  17. 

with  the   tuyeres    in  full  operation ;   the  other,  a  similar  sec- 
tion, where  the  fluid  metal  is  presumed  to  be  purified,  and   in 
o 


66  THE   PRACTICAL   METAL-WORKEK  3   ASSISTANT. 

the  act  of  being  poured  out  into  the  moulds  and  formed  into 
ingots.  In  each  of  these  sections  the  peculiar  lip-like  form 
of  the  spout  n  of  the  vessel  is  shown.  This  projecting  spout 
is  for  the  purpose  of  running  out  the  fluid  metal,  and  is 
made  to  project  from  the  vessel  so  far  as  to  bring  it  in  a  line 
with  the  axis,  so  that  into  whatever  position  the  vessel  a  may 
be  moved,  the  extremity  of  the  lip  n  may  retain  the  same  position, 
or  nearly  so  ;  thus  allowing  the  stream  of  metal  flowing  over  it  to 
fall  into  the  ingot-mould.  By  reference  to  Fig.  17  it  will  be  seen 
that  at  m'  the  lining  is  formed  so  as  to  prevent  the  slag  and  other 
impurities  floating  on  the  surface  from  flowing  out  until  after  the 
metal  itself  has  run  out.  On  each  side  of  the  spout  n  there  is  a 
.  16),  by  means  of  which  the  flame  and  gaseous 


products  evolved  during  the  process  may  escape  ;  but  the  plashes 
of  metal  thrown  up  by  jets  of  air  are,  for  the  most  part,  prevented 
from  escaping  by  the  serpentine  form  of  these  outlets  in  the  con- 
verting vessel. 

Having  thus  minutely  described  this  apparatus,  let  us  follow  its 
author  through  the  process.  When  the  chamber  is  about  half-filled 
with  fluid  metal  drawn  from  a  smelting  or  remelting  furnace,  atmos- 
pheric air,  either  in  a  cold  or  heated  state,  or  gaseous  products  capable 
of  evolving  combustion  of  the  carbon  contained  in  the  iron,  is  blown 
or  forced  into  and  among  the  fluid  metal ;  and  this  is  found  suf- 
ficient to  keep  up  the  required  temperature  during  the  process. 

The  size  and  number  of  jets  or  tuyere-pipes  required  for  this 
purpose  vary  according  to  the  quantity  of  metal  operated  upon 
at  a  time,  and  also  with  the  condition  and  quality  of  the  metal  ; 
thus  forge,  pig,  or  refined  plate  metal,  will  not  require  so  much 
oxygen  to  complete  its  carbonization  and  conversion  into  malleable 
iron,  as  is  required  for  the  conversion  of  crude  iron  of  the  quality 
known  as  No.  1  or  No.  2  foundry-iron.  To  these  qualities  of 
metal  a  tuyere  is  required  having  an  outlet  larger  by  about  twenty 
per  cent,  than  is  used  for  the  white  qualities  of  iron.  The  patentee 
hesitates,  however,  in  giving  any  fixed  rule  where  so  much  de- 
pends upon  the  force  or  pressure  of  the  blast  and  the  quality  of 
the  iron,  preferring  to  give  the  following  example  from  his  own 
practice  as  a  guide  to  the  workmen.  "  When  using  foundry -iron 
of  the  quality  No.  2,"  he  says,  "  I  run  one  ton  into  the  converting 
vessel,  in  which  it  rises  to  the  height  of  about  a  foot  above  the 
orifices  of  the  tuyere  pipes ;  and  then  force  into  the  fluid  metal, 
atmospheric  air  in  its  natural  state,  under  a  pressure  of  about  ten 
pounds  to  the  square  inch,  employing  from  six  to  twelve  tuyere- 
pipes  for  its  distribution,  the  united  area  of  the  pipes  being  two 
square  inches.  The  quantity  of  blast  admitted  by  this  area  of 
inlet,  will  in  general  be  found  sufficient  to  effect  the  conversion  of 
the  crude  iron  into  a  malleable  condition  in  about  thirty  minutes. 
Where  a  mixture  of  oxygen  gas  with  atmospheric  air  or  steam,  or 
steam  alone ;  or  where  other  gaseous  fluids  capable  of  evolving 
oxygen  are  preferred  in  lieu  of  atmospheric  air ;  then  the  size  of 


RECENTLY   PATENTED   REFINING   PROCESSES.  67 

the  tuyere-pipes  should  be  regulated  according  to  the  quantity  of 
oxygen  present,  diminishing  the  area  of  the  pipes  where  the  oxy- 
gen is  in  excess,  and  increasing  the  area  where  the  quantity  is 
short  of  the  above  proportion." 

When  the  vessel  is  new,  or  newly  lined,  it  may  be  heated  by 
the  waste  gases  of  the  blast-furnaces,  or  any  other  conveniemt 
means,  previous  to  the  crude  iron  being  poured  in.  The  patentee 
sums  ,up  the  substance  of  his  discovery  in  the  following  terms : 
"  It  is  well  known  that  molten  crude  iron,  under  ordinary  circum- 
stances, will  soon  become  solidified  unless  a  powerful  fire  is  kept 
up,  and  is  applied  direct  to  the  fluid  metal,  or  to  the  exterior  of 
the  vessel  containing  it.  It  is  also  well  known  that  if  the  quantity 
of  carbon  which  is  usually  associated  with  crude  iron  is  dimin- 
ished, that  the  temperature  necessary  to  maintain  its  fluidity  also 
rises  in  like  manner,  so  that  when  iron  has  lost  the  whole  or  the 
greater  part  of  its  combined  carbon,  the  metal  can  only  be  kept  in 
a  fluid  state  by  the  heat  of  powerful  furnaces.  Bat  I  have  dis- 
covered that  if  atmospheric  air  or  oxygen  is  introduced  into  the 
metal  in  sufficient  quantities,  it  will  produce  a  vivid  combustion 
among  the  particles  of  fluid  metal,  and  retain  and  increase  its  tem- 
perature to  such  a  degree  that  the  metal  will  continue  fluid  during 
its  transition  from  crude  iron  to  the  shape  of  cast-steel  or  mallea- 
ble iron  without  the  application  of  fuel,  the  high  temperature 
being  obtained  by  the  oxygen  uniting  with  and  causing  a  com- 
bustion of  the  carbon  in  the  crude  iron,  and  by  the  combustion  of 
small  portions  of  the  iron  itself." 

As  a  matter  of  convenience,  the  patentee  suggests,  while  re- 
serving his  right  to  apply  modifications  of  the  apparatus  described, 
that  the  converting  vessel  should  be  placed  near  to  the  discharge- 
hole  of  the  blast  or  remelting  furnace,  from  which  the  crude  iron 
is  to  be  drawn ;  that  the  interior  of  the  chamber  should  be  heated 
by  burning  gases,  or  by  introducing  wood-charcoal  or  coke  at  the 
passages  p  (Fig.  16) ;  and  that  a  blast  of  air  be  turned  on  through 
the  tuyere-pipes,  by  which  their  combustion  may  be  kept  up  and 
the  vessel  dried  before  turning  the  crude  metal  into  it.  For  this 
operation  the  vessel  is  placed  in  the  position  shown  by  Fig.  16, 
having  a  movable  gutter  leading  from  the  tap-hole  of  the  smelting 
furnace  into  the  upper  end  of  one  of  the  passages  p,  the  tuyere- 
pipes  being  now  in  operation.  As  soon  as  the  metal  covers  the 
orifices  of  the  tuyere-blocks,  a  violent  ebullition  is  produced,  the 
air  dividing  into  globules,  and  diffusing  itself  among  the  particles 
of  fluid  iron,  and  thus  coming  in  contact  at  numerous  points  with 
the  carbon  consumed  in  the  crude  iron,  and  producing  thereby  a 
vivid  combustion,  while  the  gaseous  products  escape  by  the  pas- 
sages p. 

In  about  fifteen  minutes  from  the  time  of  commencing  the  pro- 
cess, large  frothy  slags  are  thrown  violently  out  of  the  passages  p, 
accompanied  by  a  rush  of  bright  flame.  After  a  few  minutes' 
duration  this  eruption  ceases,  but  copious  flarne  still  continues  to 


68  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

escape  by  the  passages.  At  this  stage  of  the  process  the  crude 
metal  has  thrown  off  the  bulk  of  its  impurities,  and  is,  in  all  prob- 
ability, in  the  state  of  cast-steel ;  its  exact  state,  however,  can  be 
ascertained  by  turning  the  handle-shaft  f,  so  as  to  bring  the  vessel 
round  on  its  axis,  as  in  Fig.  17,  when  a  portion  of  the  metal  may 
be  discharged  into  an  ingot-mould,  where  it  is  quickly  cooled  and 
examined.  If  not  sufficiently  decarbonized,  the  vessel  is  restored 
to  its  original  position,  and  the  process  continued  until  completed, 
— from  five  to  ten  minutes'  blowing  being  generally  found  sufficient 
to  convert  the  metal  from  the  condition  of  cast-steel  to  malleable 
iron.  When  it  is  necessary  to  suspend  the  operation  of  blowing 
for  a  short  time,  the  vessel  should  be  brought  into  a  position  half- 
way between  Figs.  16  and  17,  so  that  the  orifice  of  the  tuyere- 
pipes  may  be  above  the  surface  of  the  metal,  otherwise  the  tuyeres 
will  be  stopped  up  with  the  fluid  metal.  The  whole  process  of 
conversion  from  crude  pig-iron  No.  1  to  malleable  iron,  occupies 
from  thirty  to  thirty-five  minutes,  varying  according  to  the  quality 
of  the  pig ;  but  the  exact  point  when  the  process  should  cease, 
will  soon  be  acquired  by  the  workmen,  since  the  color  and  volume 
of  the  flame  issuing  from  the  passages  vary  with  the  condition 
of  the  metal,  thus  forming  a  good  guide  for  the  workmen ;  while 
the  facility  with  which  trial-ingots  may  be  taken  affords  an  in- 
fallible test. 

The  heat,  in  some  cases,  is  so  excessive  that  the  metal, 'even 
when  reduced  to  malleable  iron,  is  still  so  far  above  the  melting 
point  that  its  temperature  requires  to  be  reduced  before  casting. 
For  this  purpose,  the  vessel  is  brought  into  the  position  half-way 
between  that  shown  in  Figs.  16  and  17,  the  tuyeres  being  above 
the  surface  of  the  metal,  the  supply  of  air  stopped,  and  a  fire-brick 
placed  over  the  orifice  of  the  passage  p,  so  as  to  prevent  the  heat 
from  escaping  with  too  much  rapidity.  In  this  way  the  tempera- 
ture gradually  subsides,  and  the  metal  is  brought  into  a  proper 
state  for  casting ;  or,  if  that  is  preferred,  for  taking  out  of  the  ves- 
sel in  masses  after  cooling  down  by  stirring. 

We  have  now  to  deal  with  a  part  of  the  refining  process  in 
which  it  occurs  to  us  that  Mr.  Bessemer  has  been  altogether  mis- 
understood, both  by  those  who  have  criticised  his  inventions  most 
severely,  and  by  the  general  public.  The  notion  generally  enter- 
tained, we  believe,  is  that  by  means  of  combustion  alone,  and  with- 
out fuel,  that  gentleman  professes  to  produce  malleable  iron.  This 
is  not  so.  He  only  professes  to  have  discovered,  that  the  rapid 
union  of  carbon  and  oxygen  which  takes  place  at  the  temperature 
which  has  now  been  attained,  still  further  increases  the  tempera- 
ture of  the  metal,  while  the  diminished  quantity  of  carbon  present 
allows  a  part  of  the  oxygen  to  combine  with  the  iron,  which  un- 
dergoes combustion,  and  is  converted  into  an  oxide. 

At  the  excessive  temperature  which  the  metal  has  now  acquired, 
he  continues,  the  oxide  undergoes  fusion,  and  forms  a  powerful 
solvent  of  those  earthy  bases  that  are  associated  with  the  iron, 


RECENTLY   PATENTED   REFINING   PROCESSES. 


69 


The  violent  ebullition  which  is  going  on  mixes  most  intimately 
the  scoria  and  metal,  every  part  of  which  is  thus  brought  in  con- 
tact with  the  fluid  oxide,  which  will  thus  wash  and  cleanse  the 
metal  most  thoroughly  from  the  silica  and  other  earthy  bases  which 
are  combined  with  the  crude  iron,  while  the  sulphur  and  other 
volatile  matters  which  cling  so  tenaciously  to  iron  at  ordinary  tem- 
peratures are  driven  off,  the  sulphur  combining  with  the  oxygen 
and  forming  sulphurous  acid  gas, — producing  by  this  means  a 
purep  iron  by  the  application  of  atmospheric  air  to  the  fluid  metal 
than  could  be  produced  in  the  puddling-furnace  by  a  large  con- 
sumption of  that  costly  material.  Beyond  that,  the  process  recom- 
mended very  much  resembles  the  mechanical  appliances  by  which 
malleable  iron  is  produced  by  the  older  methods :  namely,  by  sub- 
jecting the  ingots  at  a  wading  heat  to  a  forge-hammer  or  squeezer 
of  a  peculiarly  powerful  construction. 

During  the  interval  occupied  in  cooling  down  the  boiling  metal, 
the  workman  has  to  prepare  his  ingot-moulds.  A  convenient 
mode  of  doing  this  is  to  place  them  in  an  iron  truck,  mounted  on 
wheels,  which  may  be  moved  under  the  spout  of  the  vessel,  an>l 
passed  out  under  the  arched  openings  left  in  the  furnace.  Th'; 
ingots  thus  prepared,  are  now  in  a  fit  state  for  being  hammered, 
tilted,  or  rolled  into  bars,  rods,  or  plates.  In  some  cases  the  ingots 
are  found  to  contain  cells  and  cavities ;  in  this  case  they  are  sub- 
jected  at  a  welding  heat  to  the  action  of  squeezers,  or  they  are 
subjected,  in  a  suage  or  die,  to  repeated  blows  under  a  powerful 
hammer,  so  that  the  parts  are  forcibly  driven  together,  and  the 
cells  welded  before  being  subjected  to  the  rolling-mill  or  tilt- 
hammer. 

The  squeezers,  and  other  apparatus  recommended  by  Mr.  Besse- 
mer, differ  considerably  from  those  generally  in  use.  The  squeezer 
has  transverse  grooves,  both  on  the  upper  and  lower  jaws,  as  repre- 
sented in  Fig.  18:  A  A  being  the  grooves  or  hollows,  B  an  ingot 


Fig.  18. 


placed  between  the  jaws.     In  this  operation  the  ingot,  or  mass  of 
metal,  isjbrought  to  suoh  a  temperature  in  a  suitable  furnace  as 


Fig.  19. 


70  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

will  sufficiently  soften  it  to  admit  of  its  being  pressed  into  a  solid 
homogeneous  body. 

The  same  effect  may  be  produced  by  hammering  the  ingot  on  a 
suage  or  die,  as  illustrated  in  Fig.  19,  -Where  P  represents  the  lower 
portion  of  a  steam-hammer,  having  a  grooved 
block  Q  fitted  into  it ;  a  similar  block  N  is  se- 
cured to  a  heavy  mass  of  metal  0,  which  forms 
the  bed  of  the  hammer;  M  being  awrought-iron 
hoop,  lined  with  steel,  which  is  made  so  as  to 
slide  up  or  down  by  means  of  the  rods  S.   The 
workman,  having  heated  the  ingot  G,  holds  it 
with  a  pair  of  tongs  in  the  groove  of  the  lower 
block,  while  the  upper  one  falls  upon  it  with 
such  force  as  is  neceSfeary.   By  the  use  of  these 
grooved  surfaces,  or  suages,  the  ingot  of  metal 
is  less  liable  to  be  crushed  than  when  ham- 
mered between  two  parallel  flat  surfaces,  which  give  no  support 
to  its  sides.   In  this  operation  the  work- 
man will  move  the  ingot  backwards  and 
forwards,  turn  it  over  on  its  side,  and 
so  work  and  compress  the  metal  while 
at  a  welding  heat,  as   thoroughly   to 
F}    2Q  solidify  the  iron  and  render  it  fit  for 

the  tilt  hammer  or  rolling-mill. 

Other  modifications  of  the  steam-hammer  are  mentioned  by 
Mr.  Bessemer,  all  however  having  one  principle,  viz.,  that  the  ingot 
is  placed  upon  a  block  or  anvil,  supported  on  both  sides  by  strong 
rests,  while  the  hammer  falls  into  the  groove  formed  by  these  sup- 
ports. By  this  means  the  tendency  of  the  ingots  to  crush  out  lat- 
erally is  prevented,  while  the  metal  'is  left  at  liberty  to  expand  itself 
in  length,  thus  undoubtedly  encouraging  the  fibrous  condition  insep- 
arable from  malleable  iron.  This  effect  is  produced  by  many 
modifications  of  apparatus,  the  details  of  which  are  unimportant, 
provided  the  dies  or  suages  are  so  constructed,  and  the  ingot  of 
spongy  or  cellular  metal  so  confined,  that  when  the  hammer  is 
brought  forcibly  in  contact  with  it  the  tendency  is  to  have  its 
various  parts  forcibly  squeezed,  pressed,  or  driven  together,  the 
pores  closed,  and  the  surfaces  united  or  welded  together. 

In  the  probationary  state  of  these  patented  processes  it  is  im- 
possible to  draw  any  decided  conclusions  as  to  their  probable  re- 
sults. There  is  that  in  Mr.  Bessemer's  process  which  has  strongly 
impressed  the  public  mind,  and  which  only  the  conviction  of  com- 
plete success  or  failure  will  satisfy.  While  the  popular  view  has 
thus,  sometimes  with  little  knowledge  of  the  subject,  magnified  the 
discovery  far  beyond  its  merits,  there  have  not  been  wanting  others 
who  would  divest  it  of  any  merit  whatever,  and  treat  it  as  alto- 
gether unworthy  of  serious  consideration.  As  in  most  other  cases, 
truth  seems  to  lie  between  these  extremes. 

We  have  already  seen  that  the  principal  impurities  infcast-iron 


BECEXTLY  PATENTED  EEFIN1XG  PROCESSES.        71 

consist  of  carbon,  sulphur,  phosphorus,  silicon,  and  some  other 
substances  of  less  importance.  These  substances,  Mr.  Bessemer 
asserts,  combine  with  oxygen  at  a  high  temperature,  forming  vola- 
tile compounds,  which  are  incapable  of  again  entering  into  com- 
bination with  the  metal.  The  principle  of  Mr.  Bessemer's  process 
is  to  take  advantage  of  this  tendency  of  the  substances  to  unite 
with  oxygen.  By  forcing  atmospheric  air  into  the  fluid  metal,  in- 
tense combustion  is  produced ;  the  volatile  gases  unite  with  the 
oxygen,  and  disappear  through  the  channels  prepared  for  their 
exit.  This,  say  some  of  the  objectors,  is  unsound  in  theory — that 
practically  neither  sulphur  nor  phosphorus,  the  two  substances 
most  injurious  to  iron,  are  separated  by  the  process. 

In  support  of  these  views,  a  writer  in  the  "  Birmingham  Jour- 
nal," to  whom  we  are  indebted  for  some  excellent  remarks  on  this 
process,  some  of  which  have  been  imported  into  these  pages,  thus 
reiterates  his  objections.  Eecurring  to  objections  formerly  urged 
against  the  process  in  the  pages  of  the  same  journal,  the  writer 
says: 

"Especially  important  too,  is  it,  that  accurate  chemical  analysis 
should  be  resorted  to,  to  show  the  composition  of  this  iron,  and  to 
prove  that  the  new  process  will  truly  purge  it  of  sulphur  and 
phosphorus,  as  we  understand  Mr.  Bessemer  to  say  it  will — ele- 
ments, the  presence  of  one  per  cent,  of  which  is  fatal  to  the  quality 
of  the  iron. 

"  So  far  as  we  are  aware,  this  important  information  has  not  been 
communicated  to  the  public ;  and  so  long  a  time  has  now  elapsed 
that  we  despair  of  receiving  it  from  the  quarter  it  was  most  natu- 
rally expected  from.  In  the  hope  of  contributing  to  the  settle- 
ment of  a  question  which  has  already  too  long  disturbed  the 
public  mind,  we  have  imposed  upon  ourselves  a  task  which  we 
think  should  have  been  spared  us,  and  present  to  our  readers  such 
an  analysis  of  Mr.  Bessemer's  iron  as  we  have  been  daily  hoping 
to  see  published  by  that  gentleman  himself.  The  specimen  we 
have  experimented  upon  possesses  those  physical  properties  which, 
from  repeated  descriptions,  the  public  are  sufficiently  familiar  with. 
The  iron  consists  of  an  agglutinated  mass  of  large  brilliant  crys- 
talline grains,  possessed  of  a  very  imperfect  malleability  ;  flatten- 
ing under  the  blow  of  a  hammer  ;  but  almost  invariably  cracking 
at  the  edges.  It  is  wholly  destitute  of  a  fibrous  structure,  and  only 
after  having  been  repeatedly  heated  and  drawn  out  in  a  smith's 
forge,  exhibits  the  properties  of  an  inferior  wrought  iron.  On 
analysis  it  was  found  to  have  the  following  composition : 

Iron 98-9 

Phosphorus 1/08 

Sulphur 0-16 

Carbon 0'05 

Silicon traces 

10012 


72  THE   PRACTICAL   METAL-WOKKER'S  ASSISTANT. 

"  This  composition  is  so  accordant  with  the  physical  properties 
of  iron,  that,  the  composition  being  given,  the  chemist  would  have 
no  difficulty  in  predicating  its  more  marked  characteristics.  Its 
crystalline  structure  and  fusibility  are  very  satisfactorily  accounted 
for.  In  order  more  exactly  to  illustrate  the  nature  of  the  change 
effected  by  Mr.  Bessemer's  treatment,  we  append  an  analysis  of 
refined  iron  produced  at  a  large  establishment  in  the  neighborhood 
of  Birmingham.  We  are  indebted  to  the  courtesy  of  Dr.  Percy 
for  this  analysis.  It  was  made  in  his  laboratory  by  one  of  his 
assistants,  Mr.  Dick.  The  iron  was  obtained  only  a  few  months 
ago,  and  may  be  regarded  as  representing  the  average  composition 
of  refined  iron  as  made  at  the  present  moment  in  this  neighbor- 
hood: 

Iron ,,.v..,.     .  9514 

Carbon  (combined) 3*07 

Phosphorus 0-734 

Silicon  .    ..  :.*.-.. 0-63 

Sulphur 0-157 

Manganese trace 

Kesidue,  insoluble  in  hydrochloric  acid      .     0'53 

100-261 
The  residue,  insoluble  in  hydrochloric  acid,  yielded : 

Silica 0-3 

Alumina,  with  a  little  peroxide  of  iron    .     .     0-14 

0-44 

"  In  contrasting  the  change  effected  by  Mr.  Bessemer's  treatment 
with  that  of  the  refinery,  the  following  particulars  force  themselves 
strongly  upon  our  notice.  Mr.  Bessemer's  method  removes  most 
effectually  the  carbon  and  silicon,  while  in  the  refinery  these  are 
but  little  diminished.  The  carbon  is  eliminated  with,  a  perfection 
which  we  should  scarcely  have  thought  possible,  but  we  are  with- 
out information  as  to  the  sacrifice  at  which  this  has  been  effected. 
The  amount  of  iron  oxidized  by  the  vivid  combustion  which 
Mr.  Bessemer  induces,  we  are  unable  to  ascertain.  The  point 
which  most  prominently  strikes  the  chemist  in  Mr.  Bessemer's 
iron,  is  the  large  amount  of  phosphorus  which  it  contains — an 
amount  utterly  fatal,  we  fear,  to  the  value  of  Mr.  Bessemer's 
method.  His  treatment,  we  suspect,  does  not  sensibly  diminish  the 
amount  of  this  element ;  but  this,  too,  is  a  point  on  which  we  must 
be  dependent  on  Mr.  Bessemer.  We  have  had  no  opportunity  of 
examining  the  slag  produced  in  the  treatment ;  but  we  learn  from 
an  eminent  chemical  authority,  that  at  least  one  sample  of  it  con- 
tains no  sensible  amount  of  phosphoric  acid.  We  have  previously 
explained  that  it  is  by  the  puddling  process  that  the  phosphorus 
and  sulphur  are  mainly  removed  ;  the  chemical  examination  of  the 
tap-cinder  of  the  puddling  furnace  disclosing  an  abundance  of 
phosphoric  acid.  As  yet,  so  far  as  we  can  learn,  Mr.  Bessemer  has 


RECENTLY   PATENTED   REFINING   PROCESSES.  73 

done  nothing  towards  the  removal  of  this  pernicious  element,  phos- 
phorus ;  and  in  this  important  respect  his  process  must  be  re- 
garded as  a  failure." 

We  have  elsewhere  incidentally  alluded  to  the  strange  oversight 
committed  by  the  objectors  to  Mr.  Bessemer's  process — all  allusion 
to  his  hammering  and  squeezing  processes  are  invariable  suppressed ; 
consequently  certain  magical  results  are  expected,  to  which,  as  it 
appears  to  us,  he  does  not  lay  claim.  On  the  contrary,  his  specifi- 
cation, distinctly  claims  the  peculiar  squeezing  and  hammering 
process  already  described ;  lateral  compression  and  elongated  fibrous 
expansion  being  the  results  sought  for.  It  is  true,  he  only  mentions 
this  portion  of  his  improvements  incidentally,  when  he  claims  for 
the  new  process  facilities  for  forming  large  masses  of  iron  capable 
of  producing  bars  that  could  not  have  been  obtained  by  the  old 
process  by  means  of  powerful  machinery  not  yet  matured,  whereby 
great  labor  will  be  saved  and  the  operation  greatly  expedited.  It 
is  obvious,  therefore,  that  great  importance  is  attached  by  the  pat- 
entee to  the  subsequent  operations.  Nevertheless,  with  all  our 
desire  to  see  Mr.  Bessemer's  process  crowned  with  success,  we  can- 
not avoid  seeing  that  it  has  yet  much  to  overcome.  Early  in  Oc- 
tober, Mr.  Bessemer  sent  ingots  of  his  pneumatically  refined  iron 
to  the  Dowlais  iron- works,  where  it  was  operated  upon,  the  result 
being  a  fair-faced  iron,  equal,  apparently,  on  the  outer  surface,  to 
any  ever  rolled.  It  stood  the  lever  or  dead  test  well ;  but  the  sharp 
blow  of  the  ram,  and  the  sharp  squeeze  of  the  eccentric  straightener, 
it  could  not  bear,  for  which  its  steely  or  crystalline  structure  prob- 
ably accounts.  Practical  men  observed,  that  along  the  surface  of 
the  rail  a  stratum  of  fibrous  iron — evidently  the  result  of  elongation 
through  the  rolls — presented  itself;  and  this  was  considered  great 
encouragement  for  Mr.  Bessemer  to  prosecute  his  idea  to  perfection. 

In  reference  to  this  railway  bar,  Mr.  Bessemer  states,  that  it  was 
rolled  direct  from  a  ten-inch  square  ingot,  having  passed  through 
the  rolls  fourteen  time,s.  The  metal  was  not  previously  piled  or  in 
any  way  wrought ;  but,  notwithstanding  the  extremely  difficult  sec- 
tion, not  the  smallest  portion  of  the  flange  was  torn  up.  To  render 
the  fabrication  of  the  same  form  of  rail  practicable  on  the  old  plan, 
twice-rolled  iron  is  used  to  form  the  flange,  and  ten  shillings  per 
ton  extra  is  being  paid  for  it  in  consequence. 

The  process  is  stated  to  have  been  successfully  applied  to  the 
manufacture  of  iron  for  tin-plating.  The  best  puddle-iron  has 
heretofore  failed  to  produce  the  requisite  toughness,  and  charcoal- 
smelted  iron  has  in  consequence  been  used  for  this  purpose  at  a 
considerable  extra  cost  per  ton ;  but  we  have  examined  sheets 
rolled  from  ingots  prepared  by  the  new  process,  remarkable  for 
their  thinness,  and  affording  proofs  of  the  great  ductility  and  tough- 
ness of  its  product. 

We  have  also  inspected,  as  instances  of  the  extreme  tenacity 
capable  of  being  produced  by  this  process,  rolled  out  metal  of  sur,h 
extreme  thinness  and  pliability  ;is  to  bear,  when  annealed,  a  close 


7-i  THE   PRACTICAL   METAL-WORKERS    ASSISTANT. 

resemblance  in  fabric  to  paper,  with  much  greater  toughness  and 
tenacity. 

We  shall  conclude  these  remarks  by  quoting  the  concluding 
portion  of  Mr.  Bessemer's  address  to  the  British  Association : — 
"  One  of  the  most  important  facts,"  he  says,  "  connected  with  the 
new  system  of  manufacturing  malleable  iron  is,  that  all  the  iron  so 
produced  will  be  of  that  quality  known  as  charcoal  iron ;  not  that 
any  charcoal  is  used  in  its  manufacture,  but  because  the  whole  of 
the  processes  following  the  smelting  of  it  are  conducted  entirely 
without  contact  with,  or  the  use  of,  mineral  fuel.  The  iron  result- 
ing therefrom  will,  in  consequence,  be  perfectly  free  from  those  in- 
jurious properties  which  that  description  of  fuel  never  fails  to 
impart  to  iron  that  is  brought  under  its  influence.  At  the  same 
time,  this  system  of  manufacturing  malleable  iron  offers  extraordi- 
nary facility  for  making  large  shafts,  cranks,  and  other  heavy 
masses ;  it  will  be  obvious  that  any  weight  of  metal  that  can  be 
founded  in  ordinary  cast-iron  by  the  means  at  present  at  our  dis- 
posal may  also  be  founded  in  molten  malleable-iron,  and  be  wrought 
into  the  forms  and  shapes  required,  provided  that  we  increase  the 
size  and  power  of  our  machinery  to  the  extent  necessary  to  deal 
with  such  large  masses  of  metal.  A  few  minutes'  reflection  will 
show  the  great  anomaly  presented  by  the  scale  on  which  the  con- 
secutive processes  of  iron-making  are  at  present  carried  on.  The 
little  furnaces  originally  used  for  smelting  ore,  have  from  time  to 
time  increased  in  size,  until  they  have  assumed  colossal  proportions, 
and  are  made  to  operate  on  200  or  300  tons  of  materials  at  a  time, 
giving  out  ten  tons  of  fluid  metal  at  a  single  run.  The  manufac- 
turer has  thus  gone  on  increasing  the  size  of  his  smelting  furnaces, 
and  adapting  to  their  use  the  blast  apparatus  of  the  requisite  pro- 
portions, and  has,  by  this  means,  lessened  the  cost  of  production  in 
every  way ;  his  large  furnaces  require  a  great  deal  less  labor  to 
produce  a  given  weight  of  iron,  than  would  have  been  required  to 
produce  it  with  a  dozen  furnaces ;  and  in  like  manner  he  dimin- 
ishes his  cost  of  fuel,  blast,  and  repairs,  while  he  insures  a  uniform- 
ity in  the  result  that  never  could  have  been  arrived  at  by  the  use 
of  a  multiplicity  of  small  furnaces.  While  the  manufacturer  has 
shown  himself  fully  alive  to  these  advantages,  he  has  still  been 
under  the  necessity  of  leaving  the  succeeding  operations  to  be 
carried  out  on  a  scale  wholly  at  variance  with  the  principles  he 
has  found  so  advantageous  in  the  smelting  department.  It  is  true 
that  hitherto  no  better  method  was  known  than  the  puddling  pro- 
cess, in  which  from  400  to  500  weight  of  iron  is  all  that  can  be 
operated  upon  at  a  time,  and  even  this  small  quantity  is  divided 
into  homoeopathic  doses  of  some  70  Ibs.  or  80  Ibs.,  each  of  which  is 
moulded  and  fashioned  by  human  labor,  carefully  watched  and 
tended  in  the  furnace,  and  removed  therefrom  one  at  a  time,  to  be 
carefully  manipulated  and  squeezed  into  form.  When  we  consider 
the  vast  extent  of  the  manufacture,  and  the  gigantic  scale  on  which 
the  early  stages  of  the  progress  are  conducted,  it  is  astonishing 


REFINING   AND   WORKING   OF   IRON. 


75 


that  no  effort  should  have  been  made  to  raise  the  after  processes 
somewhat  nearer  to  a  level  commensurate  with  the  preceding  ones, 
and  thus  rescue  the  trade  from  the  trammels  which  have  so  long 
surrounded  it." 


CHAPTER  IV. 


REFINING  AND  WORKING   OF  IBON. 

THE  iron  furnaces  of  the  United  States  are,  generally  speaking, 
superior  to  those  of  England  or  the  rest  of  Europe.  On  this  point 
and  for  the  smelting  of  iron  we  refer  our  readers  to  "  OVERMAN  on 
the  MANUFACTURE  OF  IRON,"  and  will  here  introduce  one  of  the 
many  American  improvements  in  refining.  This  is  a  method  of 
making  wrought-iron  directly  from  the  ore,  patented  by  ALEX- 
ANDER DICKERSON,  of  Newark,  N.  J.,  22d  July,  1850.  "We  have 
seen  some  of  the  iron  produced — it  is  apparently  of  the  best  quality. 

Of  this  furnace,  Fig.  21  represents  a  side  view  when  complete. 
Fig.  22,  a  longitudinal  section  of  the  same.  Fig.  23,  top  view  of 


Pig.  23. 


Fig.  21. 


-i: 


cylinders,  partly  open.  Figs.  24,  and  25,  largo  and  small  water  plates 
occupying  places  F  and  E  respectively,  through  which  small  jeta 
of  water  continually  flow,  to  prevent  the  flame  from  burning  the 


76 


THE   PEACTICAL   METAL-WORKER'S   ASSISTANT. 


cylinders.     L  and  M,  two  upright  cylinders,  standing  on  the  water 
plates ;  and  between  which  cylinders  in  space  B  are  placed  in  equal 


L 

~B  a 

z 

¥ 

1 

-     x    1 

n^4x 

alternate  layers,  the  pulverized  ore  and  charcoal,  or  25  per  cent,  in 
weight  of  anthracite  if  that  is  substituted  for  charcoal. 

The  escape  heat  passes  through  an  opening  P  in  the  arch  freely 
through  space  C  between  the  masonry  work  I)  and  the  outer  cylin- 
der L,  and  also  within  the  inner  cylinder  M  through  space  A, 
whereby  the  ore  mixed  with  the  coal  is  completely  and  uniformly 
surrounded  by  the  flame  of  heat  and  deoxidized,  and  yet  perfectly 
protected  from  the  air,  flame  and  noxious  gases.  When  thus  deox- 
idized, one  charge  of  the  ore,  by  elevating  valve  K,  is  readily  pre- 
cipitated on  the  preparatory  bottom  G ;  where  it  is  stirred  and  freed 
from  the  small  particles  of  coal  that  accompany  it  from  the  cylin- 
ders. It  is  then  passed  over  on  the  puddling  bottom  G,  where  it 
is  further  stirred  and  made  up  into  balls,  when  it  is  ready  for  the 
hammer  or  rolls. 

In  the  fire  chamber  0,  the  heat  and  flame  may  be  produced  from 
wood,  anthracite  or  bituminous  coal. 

The  whole  furnace  much  resembles  an  elongated  ordinary  pud- 
dling furnace,  with  the  addition  of  a  preparatory  bottom,  over  which 
are  placed  the  cylinders  and  their  appendages. 

While  in  operation,  the  cylinders  are  charged  from  the  top  with 
the  ore  and  coal  pulverized  and  mixed.  The  cylinders  are  kept  at 
a  red  heat.  The  ore  is  thoroughly  deoxidized  in  them,  and  de- 
posited from  them  in  successive  charges  on  the  preparatory  and 
puddling  bottoms,  as  rapidly  as  the  balls  are  taken  from  the  latter 
for  the  hammer  or  rails.  Thus  the  operation  is  continuous  and 
economical,  as  only  the  escape  heat  of  the  furnace  is  employed  in 
the  cylinders. 


REFINING   AND   WORKING   OF   IRON.  77 

The  whole  is  easily  managed  and  worked,  the  operation  is  steady, 
and  the  product  certain  and  uniform.  The  iron  produced  is 
represented  to  be  extremely  pliable,  ductile,  and  malleable,  and 
applicable  to  all  the  arts.  It  is  produced  at  a  saving  of  about 
40  per  cent,  of  any  other  process.  A  ton  and  a  half  of  anthra- 
cite coal,  and  two  and  half  to  three  tons  of  ore  make  a  ton  of 
blooms  in  twelve  hours.  A  furnace  complete  costs  from  $1,200  to 
$1,500. 

MANUFACTURE  OF  MALLEABLE  IRON. — Formerly,  wrought-iron 
was  obtained  either  directly  from  the  ore,  or  from  cast-iron,  by  a 
process  still  in  extensive  operation,  in  which  wood  charcoal  is  re- 
quired. 

PUDDLING. — The  crude  cast-iron  is  remelted  in  quantities  of 
from  half  a  ton  to  one  ton,  in  a  furnace  called  the  chafery,  or  re- 
finery, blown  with  blast ;  it  is  kept  fluid  for  about  half  an  hour,  and 
than  cast  into  a  plate  about  four  inches  thick,  which  is  purer,  finer 
in  the  grain  than  pig  metal,  and  also  much  harder  and  whiter ;  it 
is  then  called  refined  metal.  The  plate  when  cold  is  broken  up,  and 
from  two  to  four  hundred  weight  of  the  fragments,  with  a  certain 
proportion  of  lime,  are  piled  on  the  hearth  of  the  puddling  furnace, 
which  is  a  reverberatory  furnace  without  blast. 

In  about  half  an  hour  the  iron  begins  to  melt,  and  whilst  it  is  in 
the  semi-fluid  state,  the  workman  stirs  and  turns  it  about  with  iron 
tools ;  he  also  throws  small  ladles  full  of  water  upon  it  from  time 
to  time.  In  this  condition  the  metal  appears  to  ferment,  and  heaves 
about  from  some  internal  change ;  this  is  considered  to  arise  from 
the  escape  of  the  carbon  in  a  volatilized  form,  which  ignites  at  the 
surface  with  spirits  of  blue  flame :  in  about  twenty  minutes  the 
pasty  condition  gives  way,  and  the  iron  takes  a  granulated  form 
without  any  apparent  disposition  to  cohesion ;  the  fire  is  now  urged 
to  the  utmost,  and  before  the  metal  becomes  a  stiff  conglomerated 
mass,  the  workman  divides  it  into  lumps  or  balls  of  about  fifty 
pounds,  in  weight. 

These  balls  are  taken  out  one  at  a  time,  and  shingled,  or  worked 
under  a  massive  helve  or  forge-hammer,  that  weighs  six  or  eight 
tons,  and  is  moved  by  the  steam-engine :  this  compresses  the  ball, 
squeezes  out  the  loose  fluid  matter,  and  converts  it  into  a  bloom,  or 
short  rudely-formed  bar.  The  bloom  is  then  raised  to  the  welding 
heat  in  a  reheating  furnace,  and  again  passed  under  the  hammer,  or 
through  grooved  rollers,  or  it  is  submitted  to  both  processes,  by 
which  it  is  elongated  into  a  rough  bar.  The  shingling  is  sometimes 
performed  by  large  squeezers,  somewhat  like  huge  pliers,  or  by 
roughened  rollers  that  also  serve  to  compress  the  iron ;  but  the 
pondergus  flat-faced  helve  is  considered  the  more  effectively  to 
expel  the  dross  and  foreign  matters  from  the  bloom,  and  to  weld 
the  same  more  perfectly  at  every  point  of  its  length. 

The  machine  for  compressing  and  rolling  puddler's  balls,  in- 
vented by  John  F.  Winslow  of  Troy,  New  York,  is  very  effective 
and  possesses  many  advantages,  of  which  may  be  mentioned :  1. 


78  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

Great  expedition  in  shingling  puddler's  iron,  one  of  these  machines 
being  sufficient  to  do  the  work  of  twenty-five  puddling  furnaces. 
2.  The  saving  of  shinglers1  wages;  no  waste  of  iron;  turning  out 
the  blooms  while  very  hot,  enabling  the  roller  to  reduce  them  to 
very  sound  bars.  3.  The  ends  of  the  blooms  are  thoroughly  up- 
set, a  very  small  amount  of  power  operates  the  machine,  and  little 
or  no  expense  for  repairs. 

The  nature  of  the  first  part  of  this  invention  consists  in  rolling 
and  compressing  puddler's  balls  or  loops  of  iron  into  blooms,  etc,, 
by  means  of  a  rotating  cam-formed  compresser,  combined  with  two 
or  more  rollers  placed  near  to  one  another,  and  at  the  same  distance 
from  the  axis  of  motion  of  the  compresser,  so  that  the  compression 
and  elongation  of  the  loops  will  be  due  entirely  to  the  eccentricity 
of  the  compresser,  the  whole  being  so  geared  that  the  rollers  shall 
turn  in  the  direction  opposite  to  the  motion  of  the  compresser,  that 
the  loop  may  be  rotated  and  retained  between  the  rollers  and  *he 
compresser :  the  surfaces  of  the  rollers  are  formed  with  slight  pro- 
jections to  take  hold  of  and  turn  the  loop  of  iron,  and  the  surface 
of  the  cam-formed  compresser  with  teeth,  which  are  very  large  at 
first,  or  on  that  part  of  the  compresser  which  first  acts  on  the  loop, 
to  squeeze  out  the  impurities,  and  at  the  same  time  insure  the 
turning  of  the  loop,  and  then  gradually  diminished  until  the  surface 
becomes  quite  or  nearly  smooth  to  finish  the  bloom. 

And  the  second  part  of  this  invention  consists  in  combining 
with  the  compresser  and  rollers  two  cheeks,  one  on  each  side,  and 
provided  with  springs  that  force  them  towards  one  another  that 
they  may  yield  to  the  ends  of  the  loop  of  iron  as  it  is  lengthened 
out  by  the  action  of  the  compresser  and  rollers,  and  at  the  same 
time  to  make  sufficient  resistance  to  give  a  proper  form  to  the  ends 
of  the  blooms,  etc. 

And  the  third  part  of  this  invention  consists  in  combining  with 
the  compresser  and  rollers  a  feeder  or  sliding  frame,  operated  by 
a  projection  on  the  compresser  or  the  shaft  thereof,  to  carry,  in  the 
ball  of  iron  between  the  compresser  and  roller,  as  that  part  of  the 
compresser  which  is  recessed  for  that  purpose  comes  round  to  the 
proper  place  for  the  introduction  of  the  ball,  and  the  discharge  of 
the  bloom  ;  and  also  in  combining  in  like  manner  a  follower  for 
discharging  the  bloom  after  it  has  been  completed. 

(a)  represents  the  frame  of  the  machine  properly  adapted  to  the 
intended  purpose,  but  which  may  be  varied  at  pleasure.  In  ap- 
propriate boxes  (bb}  between  the'  standards  of  this  frame  run  the 
journals  of  an  eccentric  roller  (c),  the  periphery  of  which  is  cam- 
formed  and  provided  with  cogs,  for  the  purpose  of  squeezing  the 
ball  of  iron  and  forcing  out  the  impurities,  and  gradually  seducing 
its  diameter  and  elongating  it.  Below  this  squeezing  roller  are 
arranged  two  fluted  rollers  (dd)  whose  journals  are  fitted  to  ap- 
propriate boxes  in  the  frame.  These  rollers  constitute  the  concave 
on  which  the  ball  of  iron  rests  during  the  operations  of  the 
squeezer  ;  cog  wheels  (efg  h)  being  employed  to  connect  the  shaft 


REFINING   AND   WORKING   OF   IRON. 


79 


of  the  rollers  with  the  shaft  of  the  squeezer  in  such  a  manner 
that  the  peripheries  of  the  two  rollers  (dd]  shall  turn  in  the  same 
direction,  and  that  of  the  squeezer  in  a  reverse  direction,  and  thus 
cause  the  ball  or  mass  of  iron  during  the  operation  of  squeezing 


Fig.  26. 


to  rotate  about  its  axis,  or  nearly  so, — the  requisite  power  for  this 
purpose  being  communicated  to  the  machine  from  some  first  mover 
in  any  efficient  manner.  One  of  the  bottom  rollers  (d)  has  a  strong 
flanch  (i)  on  one  side  which  projects  sufficiently  to  pass  within  the 
periphery  of  that  part  of  the  squeezer  which  acts  on  the  iron, 


80  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT 

after  it  has  been  so  much  elongated  as  to  have  one  of  its  ends  ap- 
proach the  flanch,  and  therefore  towards  the  end  of  the  operation 
of  the  squeezer  that  end  of  the  bloom  or  mass  of  iron  which  is 
towards  this  flanch  will  be  upset  by  it  and  properly  formed.  On 
the  side  of  the  machine  opposite  to  the  flanch  (i)  is  a  hammer  (j) 
on  the  end  of  the  bar  (k)  which  slides  in  collars  (?).  The  face  of 
this  hammer  is  smooth,  and  made  as  hammers  for  working  iron 
usually  are,  and  its  edges  are  adapted  to  the  peripheries  of  the  two 
rollers  (dd)  and  to  that  part  of  the  periphery  of  the  squeezer  which 
acts  on  the  bloom  at  the  time  the  hammer  is  to  strike  the  ends  of 
the  bloom.  A  strong  helical  spring  surrounds  the  bar  (k)  of  the 
hammer,  one  end  bearing  against  one  of  the  collars  (I),  and  the 
other  against  the  back  of  the  hammer,  so  that  its  tension  will 
always  force  the  hammer  towards  the  flanch  (i)  of  the  roller  (d]  • 
and  towards  the  outer  end,  the  said  bar  (k)  is  provided  with  a  spur 
(m),  the  inner  face  of  which  is  slightly  rounded  to  bear  against  the 
face  of  a  cam  (ri),  so  formed  that  at  each  revolution  of  the  bottom 
rollers  it  gives  the  hammer  two  blows  upon  the  bloom,  and  at 
every  revolution  of  the  rollers  the  spring  is  liberated  and  the  ham- 
mer strikes  the  bloom,  and  thus  upsets  the  ends,  the  flanch  («')  in 
this  part  of  the  operation  performing  the  office  of  an  anvil ;  the 
face  of  the  cam  is  then  made  in  the  form  of  an  inclined  plane  to 
draw  back  the  hammer  preparatory  to  another  operation. 

Instead  of  forcing  the  hammer  towards  the  bloom  by  a  spring 
and  drawing  it  back  by  a  cam,  this  arrangement  may  be  reversed 
by  making  the  spring  simply  of  sufficient  length  to  draw  back  the 
hammer,  and  reversing  the  cam  that  it  may  force  the  hammer  to- 
wards the  bloom  at  the  required  time.  And  if  desired,  a  lever, 
operated  in  any  desired  manner,  such  as  by  a  cam  or  crank,  may 
be  used  to  operate  the  hammer  instead  of  a  cam,  and  under  this 
latter  modification  the  spring  may  be  dispensed  with  altogether  by 
connecting  the  hammer  bar  with  the  lever. 

The  bars  are  next  cut  into  short  pieces,  and  piled  in  groups  of 
four  to  six ;  they  are  again  raised  to  the  welding  heat  in  a  reheat- 
ing furnace,  and  passed  through  other  rollers  to  weld  them  through- 
out their  length,  and  reduce  them  to  the  required  sizes ;  and  some- 
times the  processes  of  cutting  and  welding  are  again  repeated  in 
the  manufacture  of  still  superior  kinds  of  iron. 

A  similar  process  of  manufacture  is  still  carried  on,  partly  with 
wood  charcoal,  in  place  of  coals  and  coke ;  the  iron  thus  manufac- 
tured, called  charcoal  iron,  is  much  purer,  but  it  is  also  more  ex- 
pensive in  England ;  it  is  sometimes,  "by  way  of  distinction,  left  in 
ridges  from  the  hammer,  when  it  is  called  dented  iron. 

The  rollers  or  rolls  of  the  iron  works  are  turned  of  a  variety  of 
forms,  according  to  the  section  of  the  iron  that  is  to  be  produced ; 
in  general  one  pair  is  used  exclusively  for  each  form  of  iron  re- 
quired ;  although  in  the  imaginary  sketch,  Fig.  27,  it  is  supposed  that 
the  shaded  portion  represents  the  upper  edge  of  the  bottom  roll ; 
and  that  the  top  roll,  which  is  not  drawn,  almost  exactly  meets  the 


REFINING   AND   WORKING   OF   IRON. 


81 


bottom  one,  with  the  exception  of  the  grooves,  and  which  are  in 
general  turned  partly  in  each  roll,  in  the  manner  denoted  by  the 
black  figures. 

Fig.  27. 
a      b     c  d        e         f 


One  pair  will  have  a  series  of  angular  grooves  for  square  iron, 
gradually  less  and  less,  as  a,  b,  c,  Fig.  27,  so  that  the  bar  may  be 
rapidly  reduced  without  the  necessity  for  altering  the  adjustment 
of  the  rolls,  which  would  lose  much  valuable  time ;  the  flat  bars  are 
prepared  square,  and  then  flattened  in  grooves,  such  as  that  at  d; 
round,  or  bolt  iron,  requires  semicircular  grooves,  e;  but  round  iron 
often  shows  a  seam  down  one  side,  from  the  thin  waste  spread  out 
between  the  rolls  being  afterwards  laid  down  without  being  welded, 
when  the  iron  is  turned  one  quarter  round  and  sent  again  through 
the  rollers :  therefore  the  best  round  works  are  mostly  forged  from 
square  bars. 

Figs. /and  g  are  described  as  angle,  and  T  iron;  these  are  par- 
ticularly used  in  making  boilers,  the  ribs  of  iron  steam- vessels ;  also 
frames,  sashes,  and  various  works  requiring  strength  with  lightness. 
Plain  cylindrical  rollers  serve  for  producing  plate  and  sheet  iron, 
which  vary  in  thickness  from  one  inch  to  that  of  writing-paper,  and 
rolls  turned  like  Fig.  i,  are  employed  for  curvilinear  ribbed  plates, 
or  the  corrugated  iron,  an  elegant  application  lately  patented  for 
roofs.  Other  rollers  composed  of  two  series  of  steeled  discs,  placed 
upon  spindles,  are  used  to  slit  thin  plates  of  iron  about  six  inches 
wide,  into  a  number  of  small  rods  for  the  manufacture  of  nails,  and 
similar  rods  are  also  made  of  larger  sizes  called  slit  iron,  they 
always  exhibit  two  ragged  edges,  and  from  being  tied  up  in  small 
parcels,  are  also  known  as  bundle  iron. 


Figs.  28 


Figs.  28,  29,  30  and  31,  represent  four  amongst  numerous  other 
sections  of  railway  iron ;  these  bars  are  produced  in  rollers  turned 
with  counterpart  grooves ;  as  before,  the  shaded  portions  represent 
fragments  of  the  lower  rollers,  and  the  upper  rollers  are  supposed 
to  occupy  the  spaces  immediately  adjoining  the  section  of  the  rails. 
For  these  also,  three,  four,  or  more  grooves,  varying  gradually  from 
that  of  the  roughly  prepared  bar,  to  that  of  the  finished  rail,  are 
employed,  and  this  in  like  manner  saves  the  necessity  for  adjusting 
the  distance  between  the  rollers  during  the  progress  of  the  work. 
6 


82  f&E   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

All  the  foregoing  rolls  are  supposed  to  be  concentric,  and  to  pro- 
duce parallel  bars  and  plates  of  the  respective  sections;  but  in 
making  fish-bellied  railway  bars  (no  longer  used),  taper  plates  for 
coach  springs,  and  similar  tapered  works,  the  rollers,  whether  plain 
or  grooved,  are  turned  eccentrically,  so  as  to  make  the  works  re- 
spectively thicker  or  deeper  in  the  middle,  as  in  Fig.  32 ;  this  re- 
quires additional  dexterity  on  the  part  of  the  workman  to  introduce 
the  material  at  the  proper  time  of  the  revolution,  upon  which  it  is 
unnecessary  to  enlarge. 

The  general  effect  of  the  manufacture  of  malleable  iron  is  to  de- 
prive the  cast-iron  of  its  carbon ;  this  is  done*  in  the  puddling  fur- 
nace ;  the  original  crystalline  structure  gives  way  to  the  fibrous, 
from  the  working  under  the  hammer  and  rollers,  by  which  every 
individual  particle  or  crystal  is  drawn'  out  as  it  were  into  a  thread, 
the  multitude  of  which  constitute  the  fibrous  bar  or  metallic  rope, 
to  which  it  has  some  resemblance  except  in  the  absence  of  twist. 
The  rod  may  now  be  bent  in  any  direction  without  risk  of  fracture  ; 
and  the  superior  kinds,  even  when  cold,  may  be  absolutely  tied  in 
a  knot,  like  a  rope,  when  a  sufficient  force  is  applied. 

Should  it  however  occur  that  the  first  operation,  or  shingling 
process,  were  imperfectly  performed,  the  error  will  be  extended  in 
a  proportional  degree  throughout  the  mass,  which  will  account  for 
the  general  continuance  of  any  imperfection  throughout  the  bar  of 
iron,  or  a  considerable  length  of  the  wire  in  which  the  reduc- 
tion or  elongation  is  further  extended ;  and  to  which  evil  all 
metals  and  alloys  subjected  to  these  processes  of  elongation  are  also 
liable. 

Malleable  iron  is  divided  into  three  principal  varieties.  First, 
red-short  iron ;  secondly,  cold-short  iron ;  thirdly,  iron  partaking 
of  neither  of  these  evils,  and  which  may  be  so  far  denominated 
pure  malleable  iron. 

The  first  kind  is  brittle  when  hot,  but  extremely  soft  and  ductile 
whilst  cold.  This  is  considered  to  result  from  the  presence  of  a 
little  carbon.  The  cold-short  withstands  the  greatest  degree  of  heat 
without  fusion,  and  may  be  forged  under  the  heaviest  hammers 
when  hot,  but  it  is  brittle  when  cold.  This  is  attributed  to  the 
presence  of  a  little  silex.  The  third  kind  is  considered  to  be  en- 
tirely free  from  either  carbon  or  silex,  etc.,  and  to  be  the  pure  sim- 
ple metal ;  but  in  the  general  way  the  characters  of  iron  are 
intermediate  between  those  described. 

From  one  and  a  half  to  two  tons  of  pig-iron  have  been  used  to 
produce  one  ton  of  malleable  iron ;  bat  the  average  quantity  is  now 
from  twenty-six  to  twenty-seven  tons  for  each  twenty  tons  of  produce. 
The  forge  pig,  ballast,  and  white  cast-iron,  is  the  kind  principally 
used,  as  it  contains  least  carbon,  the  whole  of  which  should  be  ex- 
expelled  in  the  conversion  of  the  cast  metal  into  wrought-iron. 

It  appears  to  be  unnecessary  to  attempt  any  minute  description 
of  the  different  marks  and  qualities  of  iron.  First,  as  these  de- 
scriptions have  been  minutely  given  in  many  works  ;  and  secondly, 


MANUFACTURE   OF   STEEL.  88 

as  in  common  with  most  other  articles,  the  quality  of  iron  governs 
the  price.  « 

I  will  only  add,  that  little  can  be  known  of  the  character  of  iron 
from  its  outside  appearance,  beyond  that  of  its  having  been  well 
or  ill  manufactured,  so  far  as  regards  its  formation  into  bars.  The 
smith  is  principally  guided  by  the  fracture  when  he  breaks  down 
the  iron,  that  is,  when  the  bar  is  nicked  on  opposite  sides  with  the 
cold  chisel,  laid  across  the  anvil  upon  a  strip  of  iron  near  to  the 
cut  'that  it  may  stand  hollow,  and  the  blows  of  the  pane  of  the 
sledge-hammer  are  directed  upon  the  cut. 

The  judgment  will  be  partly  formed  upon  the  force  thus  re- 
quired in  breaking  the  iron ;  ftie  weakest  and  worse  kinds  will 
yield  very  readily, — when  small,  sometimes  even  to  the  blow  of 
the  chisel  alone,  and  will  then  show  a  coarse  and  brilliant  appear- 
ance, entirely  granular  or  crystalline.  This  iron  would  be  called 
very  common  and  bad.  If,  on  the  other  hand,  the  iron  breaks 
with  difficulty,  and  the  line  of  separation,  instead  of  being  moder- 
ately flat,  is  irregular,  or  presents  what  may  be  called  a  hilly  sur- 
face, the  sides  of  which  have  a  fibrous  structure  and  a  sort  of  lead- 
colored  or  a  dull-gray  hue,  this  kind  will  have  a  large  proportion 
of  fibre,  and  it  will  be  called  excellent  tough  iron.  Other  kinds 
will  be  intermediate,  and  present  partly  the  crystalline  and  partly 
the  fibrous  appearance,  and  their  relative  values  will  depend  upon 
how  nearly  they  approach  the  one  or  other  character. 

Another  trial  is  the  extent  to  which  iron,  when  slightly  nicked, 
may  be  bent  to  and  fro  without  breaking.  The  coarse  brittle  kind 
will  scarcely  bend  even  once,  whereas  superior  kinds,  especially 
stub,  charcoal,  and  dented  irons,  will  often  endure  many  deflections 
before  fracture,  and  when  nicked  on  the  outside  only  and  doubled 
flat  together,  will  bend  as  an  arch  and  partly  split  open  through 
the  centre  of  the  bar,  somewhere  near  the  bottom  of  the  cut  made 
with  the  chisel,  the  entire  fracture  presenting  the  beautiful  fibrous 
appearance  and  dull  leaden  hue  before  described. 


CHAPTER  V. 
/ 

MANUFACTURE   OF   STEEL. 

STEEL  is  manufactured  from  pure  majueao  e  iron  by  the  process 
called  cementation.  The  Swedish  iron  from  the  Dannemora  mines, 
marked  with  the  letter  L  in  the  centre  of  a  circle,  and  called 
"  Hoop  L,"  is  generally  preferred.  Irons  of  a  few  other  marks  are 
also  used  for  second-rate  kinds  of  steel.  The  bars  are  arranged  in  a 
furnace  that  consists  of  two  troughs,  about  fourteen  feet  long  and 
two  feet  square.  A  layer  of  charcoal -powder  is  spread  over  the 
bottom,  then  a  layer  of  bars,  and  so  on  alternately.  The  full 


84  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

charge  is  about  ten  tons.  The  top  is  covered  over  first  with  char- 
coal, then  sand,  and  lastly  with  the  waste  or  slush  from  the  grind- 
stone trough,  applied  wet,  so  as  to  cement  the  whole  closely  down, 
for  the  entire  exclusion  of  the  air. 

A  coal  fire  is  now  lighted  below  and  between  the  troughs ;  and 
at  the  end  of  about  seven  days  the  bars  are  found  to  have  in- 
creased in  weight  the  one  hundred  and  fiftieth  part,  by  an  absorp- 
tion of  carbon,  and  to  present,  when  broken,  a  fracture  more  crys- 
talline, although  less  shining,  than  before.  The  bars,  when  thus 
converted,  are  also  covered  with  blisters,  apparently  from  the  ex- 
pansion of  the  minute  bubbles  of  air  within  them  ;  this  gives  rise 
to  the  appellation,  blistered  steel.  • 

The  continuance  of  the  process  of  cementation  introduces  more 
and  more  carbon,  and  renders  the  bars  more  fusible,  and  would 
ultimately  cause  them  to  run  into  a  mass  if  the  heat  were  not 
checked.  To  avoid  this  mischief  a  bar  is  occasionally  withdrawn 
and  broken  to  watch  the  progress  ;  and  the  work  is  complete  when 
the  cementation  has  extended  to  the  centre  of  the  bars.  The  con- 
version occupies,  with  the  time  for  charging  and  emptying  the 
furnace,  about  fourteen  days. 

A  very  small  quantity  of  steel  is  employed  in  the  blistered  state, 
for  welding  to  iron  for  certain  parts  of  mechanism,  but  not  for 
edge-tools.  The  bulk  of  the  blistered  steel  is  passed  through  one 
of  the  two  following  processes,  by  which  it  is  made  either  into 
shear-steel  or  cast-steel. 

Shear-steel  is  produced  by  piling  together  six  or  eight  pieces  of 
blistered-steel,  about  thirty  inches  long,  and  securing  the  ends 
within  an  iron  ring,  terminating  in  a  bar  about  five  feet  long  by 
way  of  a  handle.  They  are  then  brought  to  a  welding  heat  in  a 
furnace,  and  submitted  to  the  helve  or  tilt  hammer,  which  unites 
and  extends  them  into  a  bar  called  shear-steel,  from  its  having  been 
much  used  in  the  manufacture  of  shears  for  cloth  mills,  and  also 
German  steel,  from  having  been  in  former  years  procured  from 
that  country.  Sometimes  the  bars  are  again  cut  and  welded,  and 
called  double-shear  steel,  from  the  repetition. 

This  process  of  working,  as  in  the  manufacture  of  iron,  restores 
the  fibrous  character,  and  retains  the  property  of  welding :  the  shear 
steel  is  close,  hard,  and  elastic';  it  is  much  used  for  tools,  composed 
jointly  of  steel  and  iron ;  its  superior  elasticity  also  adapts  it  to  the 
formation  of  springs,  and  some  kinds  are  prepared  expressly  for  the 
same  under  the  name  of  spring-steel. 

In  making  cast-steel,  about  twenty-six  or  twenty -eight  pounds  of 
fragments  of  blistered-steel,  selected  from  different  varieties,  are 
placed  in  a  crucible  made  of  clay,  shaped  like  a  barrel,  and  fitted 
with  a  cover,  which  is  cemented  down  with  a  fusible  lute  that  melts 
after  a  time  the  better  to  secure  the  joining.  Either  one  or  two 
pots  are  exposed  to  a  vivid  heat,  in  a  furnace  like  the  brass-founders' 
*  air-furnace,  in  which  the  blistered-steel  is  thoroughly  melted  in  the 
course  of  three  or  four  hours ;  it  is  then  removed  by  the  workman 


MANUFACTURE   OK   STEEL.  85 

in  a  glowing  state,  and  poured  into  a  mould  of  iron,  either  two 
inches  square  for  bars,  or  about  six  by  eighteen  inches,  for  rolling 
into  sheet-steel.  For  large  ingots  the  contents  of  two  or  more  pots 
are  run  together  in  the  same  mould,  but  it  requires  extremely  great 
care  in  managing  the  very  intense  temperature,  that  it  shall  be  alike 
in  both  or  all  the  pots. 

.  The  ingots  are  reheated  in  an  open  fire  much  like  that  of  the 
common  forge,  and  are  passed  under  a  heavy  hammer  weighing 
several  tons,  such  as  those  of  iron- works;  the  blows  are  given 
gently  at  first,  owing  to  the  crystalline  nature  of  the  mass,  but  as 
the  fibre  is  eliminated  the  strength  of  the  blows  is  increased. 

Steel  is  reduced  under  the  heavy  hammer  to  sizes  as  small  as 
three-quarters  of  an  inch  square.  Smaller  bars  are  finished  under 
tilt  hammers,  which  are  much  lighter  than  the  preceding,  move 
considerably  Quicker,  and  are  actuated  by  springs  instead  of  grav- 
ity alone ;  these  condense  the  steel  to  the  utmost.  Rollers  are  also 
used,  especially  for  steel  of  round,  half-round,  and  triangular  sec- 
tions, but  the  tilt  hammer  is  greatly  preferred. 

Cast-steel  is  the  most  uniform  in  quality,  the  hardest,  and  alto- 
gether the  best  adapted  to  the.  formation  of  cutting  tools,  especially 
those  made  entirely  of  steel ;  but  much  of  the  cast-steel  will  not 
endure  the  ordinary  process  of  welding,  but  will  fly  in  pieces  under 
the  hammer  when  struck. 

In  respect  to  steel,  the  same  general  remarks  offered  upon  iron 
may  be  repeated,  namely,  that  price  in  a  great  measure  governs 
quality.  Steel  when  broken  does  not  show  the  fibrous  character 
of  iron,  and  in  general  the  harder  or  Jmrsher  the  steel,  the  more 
irregular  or  the  less  nearly  flat  will  be  its  fracture. 

The  blistered-steel  should  appear  throughout  its  substance  of  an 
uniform  appearance,  namely,  crystalline  and  coarse,  much  like  infe- 
rior iron,  but  with  less  lustre  and  less  of  the  bluish  tint ;  when  but 
partially  converted,  the  film  of  iron  will  be  readily  distinguished 
in  the  centre.  The  blistered-steel  when  it  has  been  once  passed 
through  the  fire  and  well  hammered,  assumes  as  may  be  supposed  a 
much  finer  grain,  as  in  fact  the  operation  converts  it  (although  in 
the  small  way)  into  shear-steel. 

Shear-steel  breaks  with  a  much  finer  fracture,  but  the  crystalline 
appearance  is  still  readily  distinguished.  Cast-steel  is  in  general  the 
finest  of  all  in  its  fracture,  and  unless  closely  inspected,  its  separate 
crystals  or  granulations  should  be  scarcely  observable,  but  the  ap- 
pearance should  be  that  of  a  fine,  light  slaty-gray  tint,  almost  with- 
out lustre. 

The  quality  of  steel  is  considerably  improved,  especially  as  re- 
gards cutting  tools,  when  after  being  forged  it  is  hammer-hardened, 
or  well  worked  with  the  hammer  until  quite  cold,  as  this  tends  to 
close  the  "  pores"  and  to  make  the  material  more  dense ;  above  all 
things  excess  of  heat  should  be  avoided,  as  it  makes  the  grain 
coarse  and  shining,  almost  like  that  of  bad  iron,  and  which  deteri- 
oration can  be  only  partially  restored,  by  good  sound  hammering 
under  a  peculiar  management.  The  particular  degrees  of  heat  at 


86  THE  PKACTICAL   METAL- WORKER'S  ASSISTANT. 

which  different  samples  of  iron  and  steel,  bearing  the  same  name, 
should  be  worked,  can  only  be  found  by  trial ;  and  it  would  be 
hardly  possible  to  describe  the  shades  of  difference. 

It  would  have  been  incompatible  with  the  nature  of  this  work  to 
have  entered  more  largely  into  the  manufacture  of  iron  and  steel, 
or  to  have  attempted  the  notice  of  all  the  various  alloys  of  steel 
which  have  received  many  attractive  denominations,  especially 
when  so  much  has  been  already  written  on  the  subject. 

Of  all  the  works  published  on  the  manufacture  of  iron  and  steel, 
those  of  the  most  importance  are  "Overman  on  Iron,"  Lesley's 
"Iron  Manufacturers'  Guide,"  Truran's  "Manufacture  of  Iron," 
"  Eeports  of  Experiments  on  Metals  for  Cannon,"  by  Officers  U.  S. 
Army,  Captain  Eodman's  Reports  on  the  same  subject,  "  Karsten 
on  Iron,"  and  Dr.  Hartmann's  •''  Iron  Manufacturers'  Hand  Book,"* 
the  two  latter  in  German,  and  the  collection  of  Mushet's  papers, 
which  have  appeared  in  the  "Philosophical  Magazine"  at  various 
times  subsequent  to  1798,  and  were  collected  and  published  by 
himself  under  the  title  "  Papers  on  Iron  and  Steel." 

Of  the  more  brief  and  popular  accounts  of  this  subject,  the  best 
are  Aikin's  Dictionary  of  Chemistry  and  Mineralogy ;  three  vol- 
umes on  the  Manufactures  in  Metal,  in  Lardner's  Cyclopedia ;  and 
lire's  Dictionary  of  Manufactures  and  Mines,  which  contain  a  very 
large  store  of  information  on  the  metals  generally.  The  reader  will 
also  consult  with  advantage  Aikin's  "Illustrations  of  Arts  and  Man- 
ufactures," and  an  admirable  article  in  Appleton's  "  New  American 
Cyclopedia." 


CHAPTER  VI 

FORGING   IRON  AND   STEEL. 

IN  entering  upon  this  subject,  which  performs  so  important  and 
indispensable  a  part  in  every  branch  of  mechanical  industry,  it  is 
proposed  first  to  notice  some  of  the  general  methods  pursued,  com- 
mencing with  the  heaviest  works,  and  gradually  proceeding  to 
those  of  the  smallest  proportions.  This  arrangement  however  shall 
not  prevent  us  for  greater  convenience,  giving  in  a  chapter  subse- 
quent to  this  general  view,  a  very  thorough  one  on  Wrought-Iron 
in  large  Masses,  alone. 

After  this,  the  management  of  the  fire,  and  the  degrees  of  heat 
required  for  various  purposes,  will  be  described ;  and  then  the  ele- 
mentary practice  of  forging  will  be  attempted :  those  works  made 
principally  in  one  piece  will  be  first  treated  of,  and  afterwards  such 
as  are  composed  of  two  or  more  parts,  and  which  require  the  opera- 
tion of  welding. 

*  A  translation  of  this  important  work  will  shortly  appear,  from  the  In- 
dustrial Press  of  Henry  Carey  Baird,  Philadelphia. 


TORGINQ   IRON  AND   STEEL.  87 

The  heaviest  works  of  all,  are  generally  heated  in  air  furnaces 
of  various  descriptions,  some  of  which  resemble  but  greatly  exceed 
in  size  those  employed  in  the  works  where  iron  is  manufactured, 
and  in  which  the  process  of  forging  may  be  truly  considered  to 
commence  with  the  very  first  blow  given  upon  the  ball,  as  it  leaves 
the  puddling  furnace  for  being  converted  into  a  bloom. 

At  these  works,  in  addition  to  the  ordinary  manufacture  of  bar, 
plate,  and  hoop  iron  in  all  their  varieties,  the  hammer-men  are  em- 
ployed in  preparing1  masses,  technically  called  "  uses,"  which  mean 
pieces  to  be  used  in  the  construction  of  certain  large  works,  by  the 
combination  or  welding  of  several  of  these  masses.  A  square  shaft, 
to  be  used  at  an  iron- works,  was  made  by  laying  together  sixteen 
square  pieces,  measuring  collectively  about  twenty-six  inches  square, 
and  six  feet  long.  These  were  bound  together,  and  put  into  a  power- 
ful air  furnace,  and  the  ends  of  the  group  were  welded  into  a  solid 
mass  under  the  heavy  hammer  weighing  five  tons ;  the  weld  was 
afterwards  extended  throughout  the  length.  The  paddle-shafts  of 
the  largest  steam-ships  are  wrought  by  successive  additions  at  the 
one  end,  as  follows :  A  slab  or  use  is  welded  on  one  side  close  to 
the  end,  and  when  drawn  down  to  the  common  thickness,  the 
additional  matter  becomes  thrown  into  the  length ;  the  next  use 
is  then  placed  on  the  adjoining  side  of  the  as  yet  square  shaft, 
and  also  drawn  into  the  length,  and  so  on  until  the  full  measure  is 
attained. 

These  ponderous  masses  are  managed  with  far  more  facility  than 
might  be  expected  by  those  who  have  never  witnessed  such  inter- 
esting proceedings.  First,  the  "heat'1'1  has  a  long  iron  rod  attached 
to  it  in  continuation  of  its  axis,  to  serve  as  a  "porter"  or  guide  rod ; 
the  mass  is  suspended  under  a  traversing  crane  at  that  point  where 
it  is  nearly  equipoised :  the  crane  not  only  serves  to  swing  it  round 
from  the  fire  to  the  hammer,  rjut  the  traverse  motion  also  moves 
the  work  endways  upon  the  anvil,  and  small  changes  of  elevation 
are  sometimes  affected  by  a  screw  adjustment  in  the  suspending 
chain.  The  circular  form  is  obtained  by  shifting  the  work  round 
upon  its  axis  by  means  of  a  cross  lever  fixed  upon  the  porter,  and 
moved  by  one  or  two  men,  so  as  to  expose  each  part  of  the  circum- 
ference to  the  action  of  the  helve  ;  this  is  readily  done,  as  the  crane 
terminates  in  a  pulley,  around  which  an  endless  band  of  chain  is 
placed,  and  the  work  lies  within  the  chain,  which  shifts  round 
when  the  work  is  turned  upon  the  anvil :  the  precision  of  the  forg- 
ings  produced  by  these  means  is  very  surprising.  (See  p.  110). 

A  similar  mode  of  work  is  adopted  on  a  smaller  scale  for  manv 
of  the  spindles,  shafts,  and  other  parts  of  ordinary  mechanism,  which 
are  forged  under  the  great  hammer,  often  of  several  bars  piled  to- 
gether and  fagoted ;  a  suitable  term,  as  they  are  frequently  made  of 
a  round  bar  in  the  centre,  and  a  group  of  bars  of  angular  section, 
called  mitre  iron,  around  the  same,  which  are  temporarily  wedged 
within  a  hoop,  somewhat  after  the  manner  of  a  fagot  of  wood.  Such 
works  are  likewise  made  of  scrao-iron,  which  consists  of  a  strange 


88  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

heterogeneous  medley  of  odd  scraps  and  refuse  from  a  thousand 
works,  scarcely  two  pieces  of  which  are  alike. 

A  number  of  these  fragments  are  enveloped  in  an  old  piece  of 
sheet  iron,  and  held  together  by  a  hoop,  the  mass  is  raised  to  the 
welding  heat  in  a  blast  or  air  furnace,  and  the  whole  is  consolidated 
and  drawn  down  under  the  tilt-hammer ;  one  long  bar  that  serves 
as  the  porter  being  welded  on  by  the  first  blow.  The  mingling  of 
the  fibres  in  the  scrap-iron  is  considered  highly  favorable  to  the 
strength  of  the  bar  produced.  The  scrap-iron  is  sometimes  twisted 
during  the  process  of  manufacture,  to  lay  all  the  filaments  like  a 
rope,  and  prevent  the  formation  of  spills,  or  the  longitudinal  dirty 
seams  found  on  the  surface  of  inferior  iron. 

Sometimes  the  formation  of  the  scrap-iron  is  immediately  followed 
by  the  production  of  the  shafts  and  other  heavy  works  for  which  it 
is  required ;  at  other  times  the  masses  are  elongated  into  bars  sold 
under  the  name  of  scrap-iron,  although  it  is  very  questionable  if 
all  the  iron  that  is  so  named  is  produced  in  the  manner  implied. 

The  long  furnaces  are  particularly  well  suited  to  straight  works 
and  bars,  but  when  the  objects  get  shorter  and  of  more  complex 
figures,  the  open  fire  or  ordinary  smith's  hearth  is  employed.  This, 
when  of  the  largest  kind,  is  a  trough  or  pit  of  brickwork  about  six 
feet  square,  elevated  only  about  six  inches  from  the  ground ;  the 
one  side  of  the  hearth  is  extended  into  a  vertical  wall  leading  to 
the  chimney,  the  lower  end  of  which  terminates  in  a  hood  usually 
of  stout  plate  iron,  which  serves  to  collect  the  smoke  from  the  fire. 
The  back  wall  of  the  forge  is  fitted  with  a  large  cast-iron  plate,  or 
a  back,  in  the  centre  of  which  is  a  very  thick  projecting  nozzle  also 
of  iron,  perforated  for  admitting  the  wind  used  to  urge  the  fire ;  the 
aperture  is  called  the  tuyere. 

The  blast  is  sometimes  supplied  from  ordinary  bellows  of  various 
forms ;  at  other  times,  by  three  enormous  air-pumps,  which  lead  into 
a  fourth  cylinder  or  regulator,  the  piston  of  which  is  loaded  with 
weights,  so  as  to  force  the  air  through  pipes  all  over  the  smithy,  and 
every  fire  has  a  valve  to  regulate  its  individual  blast ;  but  the  more 
modern  and  general  plan  is  the  revolving  fan,  also  worked  by  the 
engine,  the  blast  from  which  is  similarly  distributed. 

In  some  cases  the  cast-iron  forge  back  is  made  hollow,  that  a 
stream  of  water  may  circulate  through  it  from  a  small  cistern ;  the 
water-back  is  thereby  prevented  from  becoming  so  hot  as  the  others, 
and  its  durability  is  much  increased.  In  other  cases  the  air,  in  its 
passage  from  the  blowing  apparatus,  flows  through  chambers  in 
the  back  plate  so  as  to  become  heated  in  its  progress,  and  thus  to 
urge  the  fire  with  hot  blast,  which  is  by  many  considered  to  effect  a 
very  great  economy  in  the  fuel. 

Some  heavy  works  of  rather  complex  form,  such  as  anchors,  are 
most  conveniently  managed  by  hand  forging;  many  of  these  require 
two  gangs  of  men  with  heavy  sledge-hammers,  each  consisting  of 
six  to  twelve  men,  who  relieve  each  other  at  short  intervals,  as  the 
work  is  exceedingly  laborious.  Their  hammers  are  swung  round 


FORGING   IRON   AND   STEEL.  89 

and  made  to  fall  upon  one  particular  spot  with  great  uniformity ; 
the  conductor  of  this  noisy,  although  dumb  concert  so  far  as  relates 
to  voice,  stands  at  a  respectful  distance,  and  directs  the  blows  of  his 
assistants  with  a  long  wooden  wand.  The  Hercules,  or  crane,  used 
for  transferring  the  work  from  the  fire  to  the  anvil,  which  is  at 
about  the  same  elevation  as  the  fire  itself,  is  still  retained. 

The  square  shanks  of  anchors  are  partly  forged  under  a  vertical 
hammer  of  very  simple  construction,  called  a  " monkey"  It  con- 
sists of  a  long  iron  bar  running  very  loosely  through  an  eye  or 
aperture  several  feet  above  the  anvil,  and  terminating  at  foot  in  a 
mass  of  iron,  or  the  ram.  The  hammer  is  elevated  by  means  of  a 
chain,  attached  to  the  rod  and  also  to  a  drum  overhead,  which  is 
put  into  gear  with  the  engine,  and  suddenly  released  by  a  simple 
contrivance,  when  the  hammer  has  reached  the  height  of  from  two 
to  five  feet,  according  to  circumstances.  The  ram  is  made  to  fall 
upon  any  precise  spot  indicated  by  the  wand  of  the  foreman,  as  it 
has  a  horizontal  range  of  some  twenty  inches  from  the  central  posi- 
tion, and  is  guided  by  two  slight  guy  rods,  hooked  to  the  ram  and 
placed  at  right  angles ;  the  guys  are  held  by  two  men,  who  watch 
the  directions  given.  This  contrivance  is  far  more  effective  than 
the  blows  of  the  sledge-hammers,  and  although  now  but  little  used" 
is  perhaps  more  suitable  to  such  purposes  than  the  helve  or  lift- 
hammer,  which  always  ascends  to  one  height,  and  falls  upon  one 
fixed  spot. 

The  square  shank  of  the  anchor,  and  works  of  the  same  section, 
are  readily  shifted  the  exact  quarter  circle,  as  the  sling-chain  is 
made  with  flat  links,  each  a  trifle  longer  than  the  side  of  the  square 
of  the  work,  which,  therefore,  bears  quite  flat  upon  one  link,  and, 
when  twisted,  it  shifts  the  chain  the  space  of  a  link,  and  rests  as 
before. 

Many  implements  and  tools,  such  as  shovels,  spades,  mattocks, 
and  cleavers,  are  partly  forged  under  the  tilt-hammer ;  the  prepara- 
tory processes,  called  moulding,  which  include  the  insertion  of  the 
steel,  are  done  by  ordinary  hand  forging.  The  objects  are  then 
spread  out  under  the  broad  face  of  the  tilt-hammer,  the  workman 
in  such  cases  being  sometimes  seated  on  a  chair  suspended  from 
the  ceiling,  and,  by  paddling  about  with  his  feet,  he  places  himself 
with  great  dexterity  in  front  or  on  either  side  of  the  anvil  with  the 
progressive  changes  of  the  work:  the  concluding  processes  are 
mostly  done  by  hand  with  the  usual  tools.  A  similar  arrangement 
is  also  adopted  in  tilting  small-sized  steel. 

With  the  reduction  of  size  in  the  objects  to  be  forged,  the  num- 
ber of  hands  is  also  lessened,  and  the  crane  required  for  heavy  work 
is  abandoned  for  a  chain  or  sling  from  the  ceiling ;  but,  for  the 
majority  of  purposes,  two  men  only  are  required,  when  the  work 
is  said  to  be  two-handed.  The  principal,  or  the  fireman,  takes  the 
management  of  the  work  both  in  the  fire  and  upon  the  anvil ;  he 
directs  and  assists  with  a  small  hammer  of  from  two  to  four  pounds 
weight ;  the  duty  of  his  assistant  is  to  blow  the  bellows  and  wield 


90 


THE   PRACTICAL    METAL-WORKERS   ASSISTANT. 


the  sledge-hammer,  that  weighs  from  about  ten  to  fourteen  pounds, 
although  sometimes  more,  and  from  which  he  derives  his  name  of 
hammer-man. 

As  the  works  to  be  forged  become  smaller,  the  hearth  is  gradually 
lessened  in  size,  and  more  elevated,  so  as  to  stand  about  two  and  a 
half  feet  from  the  ground ;  it  is  now  built  hollow,  with  an  arch 
beneath  serving  as  the  ash-pit  to  receive  the  cinders  and  clinkers. 
The  single  hearths  are  made  about  a  yard  square,  and  those  forges 
which  have  two  fires  under  the  same  hood,  measure  about  two 
yards  by  one ;  a  double  trough,  to  contain  water  in  the  one  com- 
partment and  coals  in  the  other,  is  usually  added,  and  the  ordinary 
double  bellows  is  used.  In  proportion  as  the  hearth  is  more 
elevated,  so  is  the  anvil  likewise,  that  in  ordinary  use  standing 
about  two  feet  or  two  and  a  half  feet  from  the  ground,  its  weight 
being  from  two  to  four  hundred-weight. 

Numerous  small  works  are  forged  at  once  from  the  end  of  the 
bar  of  iron,  which  then  also  serves  the  office  of  the  porter  required 
for  heavy  masses ;  but  when  the  small  objects  are  cut  off  from  the 
bar,  or  the  pieces  are  too  short  to  be  held  in  the  hand,  tongs  of 
different  forms  are  needful  to  grasp  the  work.  These  are  made  of 
•various  shapes,  magnitudes,  and  lengths  according  to  circumstances  ; 
but  the  annexed  figures  will  serve  to  explain  some  of  the  most 
general  kinds,  although  variations  are  continually  made  in  their 
form  to  meet  peculiar  cases. 

Figs.  33  and  34  are  called  flat-bit  tongs ;  these  are  either  made  to 
fit  very  close,  as  in  Fig.  34,  for  thin  works,  or  to  stand  more  open, 


Figs.  34. 


35. 


36.         37 


38. 


as  in  Fig.  33,  for  thicker  bars,  but  always  parallel ;  and  a  ring,  or 
coupler,  is  put  upon  the  handles,  or  reins,  to  maintain  the  grip  upon 
the  work ;  others  of  the  same  general  form  are  made  with  hollow, 
half-round  bits ;  but  it  is  much  better  they  should  be  angular,  like 
the  ends  of  Fig.  35,  as  then  they  serve  equally  well  for  round  bars, 


FORGING   IRON   AND   STEEL.  91 

or  for  square  bars  held  upon  their  opposite  angles.  Tongs  that  are 
made  long,  and  swelled  open  behind,  as  in  Fig.  35,  are  very  excel- 
lent for  general  purposes,  and  also  serve  for  bolts  and  similar  objects 
with  the  heads  placed  inwards.  The  pincer  tongs,  Fig.  36,  are  also 
applied  to  similar  uses,  and  serve  for  shorter  bolts. 

Fig.  37  represents  tongs  much  used  at  Sheffield,  amongst  the 
cutlers;  they  are  called  crook-bit  tongs;  their  jaws  overhang  the  side 
so  as  to  allow  the  bar  of  iron  or  steel  to  pass  down  beside  the 
rivet,  and  the  nib  a^the  end  prevents  the  rod  from  being  displaced 
by  the  jar  of  hammering ;  these  are  very  convenient.  Fig.  38,  or 
the  hammer  tongs,  are  used  for  managing  works  punched  with 
holes,  such  as  hammers  and  hatchets:  as  the  pins  enter  the  holes, 
and  maintain  the  grasp,  they  should  be  made  stout  and  long,  so  as 
to  admit  of  being  repaired  from  time  to  time,  as  the  bits  get  de- 
stroyed by  the  fire. 

Fig.  39,  or  hoop  tongs,  are  very  much  used  by  ship-smiths,  for 
grasping  hoops  and  rings,  which  may  be  then  worked  either  on 
the  edge,  when  laid  flat  on  the  anvil,  or  on  the  side  when  upon 
the  beak-iron:  and  lastly,  Fig.  40  represents  the  smith's  pliers,  or 
light  tongs,  used  for  picking  up  little  pieces  of  iron,  or  small  tools 
and  punches,  many  of  which  are  continually  driven  out  upon  the 
ground  in  the  ordinary  course  of  work ;  they  are  also  convenient 
in  hardening  small  tools. 

In  addition  to  the  hearth,  anvil,  and  tongs,  the  smithy  contains 
a  number  of  chisels,  punches,  and  swages  or  striking  tools,  called 
also  top  and  bottom  tools,  of  a  variety  of  suitable  forms  and  gen- 
erally in  pairs ;  these  may  be  considered  as  reduced  copies  of  the 
grooves  turned  in  the  rollers,  and  occasionally  made  on  the  faces 
of  the  tilt-hammers  of  the  iron- works  for  the  production  of  square, 
flat,  round,  T  form  iron,  angle  iron,  and  railway  bars,  as  referred 
to.  The  bottom  tools  of  the  ordinary  smith's  shop,  have  square 
tangs  to  fit  the  large  hole  in  the  anvil ;  in  using  them  the  fireman 
holds  the  work  upon  the  bottom  tool,  and  above  the  work  he 
places  the  top  or  rod  tool,  which  is  then  struck  by  the  sledge-ham- 
mer of  his  assistant. 

In  fitting  the  hazel  rods  to  the  top  tools  the  rods  are  alternately 
wetted  in  the  middle  of  their  length,  and  warmed  over  the  fire  to 
soften  them,  that  portion  is  then  twisted  like  a  rope,  and  the  rod  is 
wound  once  round  the  head  of  the  tool  and  retained  by  an  iron 
ferrule  or  coupler ;  a  rigid  iron  handle  would  jar  the  hand. 

When  these  tools  are  used  for  large  works,  a  square  plate  of 
sheet-iron,  with  a  whole  punched  in  the  middle  of  it,  is  put  on  the 
rod  towards  the  tool,  to  shield  the  hand  of  the  workman  from  the 
heat ;  and  it  not  unfrequently  happens  with  such  large  works  that 
the  rod  catches  fire,  and  the  tool  is  then  dipped  at  short  intervals 
in  the  slake  trough  to  extinguish  it. 

The  smith  who  works  without  any  helpmate  is  much  more  circum- 
scribed as  to  tools,  and  he  is  from  necessity  compelled  to  abandon 
all  those  used  in  pairs,  unless  the  upper  tools  have  some  mechani- 


92 


THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 


cal  guide  to  support  and  direct  them.  In  addition  to  the  anvil  he 
only  uses  the  fixed  cutter  and  heading  tools ;  he  may  occasionally 
support  the  end  of  the  tongs  in  a  hook  attached  to  his  apron- 
string,  or  suspended  from  his  neck,  whilst  he  applies  a  hand-chisel, 
a  punch,  or  a  name-mark  in  the  left  hand,  and  strikes  with  the 
hammer  held  in  the  right.  The  method  is  however  ample  for  a 
variety  of  small  works,  such  as  cutlery,  tools,  nails,  and  small  iron- 
mongery, which  are  wrought  almost  exclusively  by  the  hand- 
hammer. 

Attempts  to  work  small  tilt-hammers  with  the  foot  have  been 
found  generally  ineffective,  as  the  attention  of  the  individual  is 
too  much  subdivided  in  managing  the  whole,  neither  is  his 
strength  sufficient  for  a  continued  exertion  at  such  work ;  but  the 
"  Oliver,'1'1  which  we  shall  now  describe,  is  one  of  the  best  tools  of 
this  class. 

THE  OLIVER,  OR  SMALL  LIFT-HAMMER. — Fig.  41  represents  a 
species  of  lift-hammer  worked  by  the  foot.  The  hammer  head  is 


Fig.  41. 

about  two  and  a  half  inches  square  and  ten  long,  with  a  swage 
tool  having  a  conical  crease  attached  to  it,  and  a  corresponding 
swage  is  fixed  in  a  square  cast-iron  anvil  block,  about  twelve 
inches  square,  and  six  deep,  with  one  or  two  round  holes  for 
punching,  etc.  The  hammer  handle  is  about  two  to  two  and  a  half 
feet  long,  and  mounted  in  a  cross  spindle  nearly  as  long,  supported  in 
a  wooden  frame  between  end  screws,  to  adjust  the  groove  in  the 
hammer  face  to  that  in  the  anvil  block.  A  short  arm,  five  or  six 
inches  long,  is  attached  to  the  right  end  of  the  hammer  axis,  and 


FORGING   IRON   AND   STEEL. 


93 


from  this  arm  proceeds  a  cord  to  a  spring  pole  overhead,  and  also 
a  chain  to  a  treadle  a  little  above  the  floor  of  the  smithy. 

When  left  to  itself  the  hammer  handle  is  raised  to  nearly  a  ver- 
tical position  by  the  spring,  and  it  is  brought  down  very  readily 
with  the  foot,  so  as  to  give  good  hard  blows  at  the  commencement 
of  moulding  the  objects,  and  then  light  blows  for  finishing  them. 
The  machine  was  used  when  the  author  first  saw  it,  in  making 
long  stout  nails,  intended  for  fixing  the  tires  of  wheels,  secured 
within  the  felloes  by  washers  and  riveting;  the  nails  were  made 
very  nicely  round  and  taper,  and  were  forged  expeditiously. 

For  single  hand-forging,  the  fire  becomes  still  further  reduced 
in  size,  and  proportionally  elevated  from  the  ground.  A  portable 
forge  of  suitable  dimensions  for  such  work,  and  made  entirely  of 
iron,  is  represented  in  Fig.  42.  The  bellows  are  placed  beneath 
the  hearth  and  worked  by  a  treadle. 


Fig.  42. 

This  forge  is  also  occasionally  fitted  with  a  furnace  for  melting 
small  quantities  of  metal,  and  with  various  apparatus  for  other 
applications  of  heat,  such  as  soldering,  either  with  a  small  charcoal 
fire,  or  a  lamp  and  blowpipe,  which  are  likewise  urged  with  the 


94-  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

bellows.  These  applications,  and  also  that  of  hardening  and  tem- 
pering tools,  which  will  be  severally  returned  to  at  their  respective 
places,  are  much  facilitated  by  the  bellows  being  worked  with  the 
foot,  as  it  leaves  both  hands  at  liberty  for  the  management  either 
of  the  work  or  fire,  with  the  so-called  fire-irons,  which  include  a 
poker,  a  slice  or  shovel,  and  a  rake,  in  addition  to  the  supply  of 
tongs  of  some  of  the  former  shown. 

The  forge  represented  is  sufficiently  powerful  for  a  moderate 
share  of  those  works  which  require  the  use  of  the  sledge-hammer ; 
but,  when  the  latter  tool  is  used,  the  anvil  should  not  fall  short  of 
one  hundred  pounds  in  weight ;  and  the  heavier  it  is,  the  less  it 
will  rebound  under  the  hammer. 

MANAGEMENT  OF  THE  FIRE  :  THE  DEGREES  OF  HEAT. — The  ordi- 
nary fuel  for  the  smith's  forge  is  coal,  and  the  kinds  to  be  pre- 
ferred are  such  as  are  dense  and  free  from  metallic  matters,  as 
these  are  generally  accompanied  with  sulphur,  which  is  highly 
detrimental. 

Copper  is  usually  forged  in  a  coke  fire — silver  and  gold  in  those 
made  of  charcoal ;  but  the  hearths  do  not  materially  differ  from 
those  used  for  iron.  Compressed  peat  charcoal  has  been  strongly 
recommended  on  account  of  its  freedom  from  sulphur — one  of  the 
greatest  enemies  in  nearly  all  metallurgic  operations. 

The  fire  is  sometimes  made  open,  at  other  times  hollow,  or  like 
a  tunnel ;  and  the  larger  the  fire  is  required  to  be,  so  much  the 
more  distant  is  it  situated  from  the  tuyere  iron.  Before  lighting  the 
fire,  the  useful  cinders  are  first  turned  back  on  the  hearth,  and  the 
exhausted  dust  or  slack  is  cleared  away  from  the  iron  back  and 
thrown  into  the  ash-pit ;  a  fair-sized  heap  of  shavings  is  then 
lighted,  and  allowed  to  burn  until  the  flame  is  nearly  extinguished, 
when  the  embers  are  covered  over  with  the  cinders,  and  the  bel- 
lows are  urged  A  dense  white  smoke  first  rises,  and,  in  two  or 
three  minutes,  the  flame  bursts  forth,  unless  the  fire  be  choked, 
when  the  poker  is  carefully  passed  into  the  mouth  of  the  tuyere. 
The  work  is  now  laid  on  the  fire,  and  covered  over  with  green  or 
fresh  coals,  which  are  beaten  around  the  tuyere  and  the  work,  the 
blast  being  continued  all  the  while ;  the  whole  mass  will  soon 
be  in  a  state  of  ignition.  A  heap  of  fresh  coals  is  always  kept  at 
the  outside  wall  of  the  fire,  and  they  are  gradually  advanced  at 
intervals  into  the  centre  of  the  flame  to  make  up  for  those  con- 
sumed. 

In  making  a  large  hollow  fire,  after  a  good-sized  fire  has  been 
lighted  in  the  ordinary  way,  the  ignited  fuel  is  brought  forward  on 
the  hearth  to  expose  the  tuyere  iron,  into  the  central  aperture  of 
which  the  poker  is  introduced.  A  mass  of  small  wetted  coal  is  beaten 
hard  round  the  poker  to  constitute  the  stock,  the  magnitude  of 
which  will  depend  on  the  distance  at  which  the  fire  is  required  to 
stand  off,  and  a  second  stock  is  also  made  opposite  the  first,  the 
two  resembling  two  hills  with  the  lighted  fuel  lying  between  them. 
The  durability  of  the  fire  will  depend  on  the  stocks  being  hard 


FORGING  IRON  AND  STEEL.  95 

rammed,  which,  for  large  works,  is  often  done  with  the  sledge- 
hammer. The  work  is  now  laid  in  the  hollow  just  opposite  the 
blast-pipe,  and  covered  on  its  two  sides  and  top  with  thin  pieces 
of  wood,  and  a  heap  of  wetted  coals  is  carefully  banked  up  around 
the  same  and  beaten  down  with  the  slice  or  shovel.  When  care- 
fully done,  the  heap  is  made  to  assume  the  smooth  form  of  an  em- 
bankment of  earthwork.  The  bellows  are  blown  gently  all  the 
time,  and  the  work  is  not  withdrawn  until  the  wood  is  consumed, 
and  the  flame  peeps  through  at  each  end  of  the  aperture,  so  as  to 
cake  the  coals  well  together  into  a  hard  mass;  after  which  the  work 
may  be  removed  or  shifted  about  without  any  risk  of  breaking 
down  the  fire. 

In  localities  where  wood  is  scarce,  small  iron  rods  are  placed 
around  the  principal  mass,  often  designated  the  heat ;  the  small 
rods  are  first  withdrawn  when  the  fire  has  burned  up,  to  allow 
room  for  the  removal  of  the  work. 

Sometimes  when  a  fire  is  required  only  for  hardening,  the  cen- 
tering of  the  arch  is  made  entirely  of  wood,  either  in  one  or  several 
pieces  :  and  in  this  manner  it  may  be  built  of  any  required  form, 
as  angular  for  knees,  circular  for  hoops,  and  so  on  (although  such 
works  are  usually  done  in  open  fires,  which  resemble  the  above  in 
all  respects,  except  the  covering-in  or  roof) :  small  coal  is  thrown 
at  intervals  into  the  hollow  fire  to  replace  that  which  is  burned, 
and  by  careful  management  one  of  these  combustible  edifices  will 
last  half  a  day,  or  even  the  entire  day,  without  renewal.  Occa- 
sionally, the  stock  around  the  tuyere  iron  will  serve  with  a  little 
repair  for  a  second  day,  if,  when  the  fire  is  turned  back  at  night,  that 
part  is  allowed  to  remain,  and  the  fire  is  extinguished  with  water. 

When  a  small  hollow  fire  is  required,  the  same  general  methods 
are  less  carefully  followed,  and  an  iron  tube  introduced  amidst  the 
coals,  makes  a  very  convenient  muffle  or  oven  for  some  purposes. 

In  forging,  the  iron  or  steel  is  in  almost  every  case  heated  to  a 
greater  or  less  degree,  to  make  it  softer  and  more  malleable  by 
lessening  its  cohesion ;  the  softening  goes  on  increasing  with  the 
accession  of  temperature,  until  it  arrives  at  a  point  beyond  that 
which  can  be  usefully  employed,  or  at  which  the  material,  whether 
iron  or  steel,  falls  in  pieces  under  the  blows  of  the  hammer,  but 
which  degree  is  very  different  with  various  materials,  and  even 
with  varieties  bearing  the  same  name. 

Pure  iron  will  bear  an  almost  unlimited  degree  of  heat.  The  hot 
short  iron  bears  much  less,  and  is  in  fact  very  brittle  when  heated. 
Other  kinds  are  intermediate.  Of  steel,  the  shear-steel  will  gen- 
erally bear  the  highest  temperature,  the  blistered-steel  the  next, 
and  the  cast-steel  the  least  of  all.  But  all  these  kinds,  especially 
cast- steel,  differ  very  much  according  to  the  processes  of  manu- 
facture, as  some  cast-steel  may  bo  readily  welded,  but  it  is  then 
somewhat  less  certain  to  harden  pjrfectly. 

Without  attempting  any  roiinel  division,  I  may  add,  the  smith 
commonly  speaks  of  live  degrees  of  temperature,  namely: 


96  THE   PRACTICAL   METAL- WORKER'S   ASSISTANT. 

The  black-red  heat,  just  visible  by  daylight ; 

The  low-red  heat ; 

The  bright-red  heat,  when  the  black  scales  may  be  seen ; 

The  white-heat,  when  the  scales  are  scarcely  visible ; 

The  welding-heat,  when  the  iron  begins  to  burn  with  vivid 
sparks. 

Steel  requires  on  the  whole  very  much  more  precaution  as  to 
the  degree  of  heat,  than  iron.  The  temperature  of  cast-steel 
should  not  generally  exceed  a  bright-red  heat ;  that  of  blistered 
and  shear-steel  that  of  a  moderate  white-heat.  Although  steel 
cannot  in  consequence  be  so  far  softened  in  the  fire  as  iron,  and  is 
therefore  always  more  dense  and  harder  to  forge  ;  still  from  its  su- 
perior cohesion  it  bears  a  much  greater  amount  of  hard  work  under 
the  hammer  when  it  is  not  over-heated  or  burned ;  but  the  small- 
est available  temperature  should  be  always  employed  with  this 
material,  as  in  fact  with  all  others. 

It  has  been  recommended  to  try  by  experiment  the  lowest  de- 
gree of  heat  at  which  every  sample  of  steel  will  harden,  and  in 
forging  always  to  keep  a  trifle  below  that  point.  This  proposal 
however  is  rarely  tried,  and  still  less  followed,  as  the  usual  attempt 
is  to  lessen  the  labor  of  forging  by  softening  the  steel  so  far  as  it 
is  safely  practicable. 

Iron  is  more  commonly  worked  at  the  bright-red  and  the  white- 
heats,  the  welding-heat  being  reserved  for  those  cases  in  which 
welding  is  required  ;  or  others  in  which,  from  the  great  extension 
or  working  of  the  iron,  there  is  risk  of  separating  its  fibres  or 
laminae,  so  as  to  cause  the  work  to  become  unsound  or  hollow 
from  the  disrupture  of  its  substance ;  whereas  the  same  processes 
being  carried  on  at  the  welding 'temperature,  the  work  would  be 
kept  sound,  as  every  blow  would  effect  the  operation  of  welding 
rather  than  that  of  separation.  The  cracks  and  defects  in  iron  are 
generally  very  plainly  shown  by  a  difference  in  color  at  the  parts 
when  they  are  heated  to  a  dull-red.  This  method  of  trial  is  often 
had  recourse  to  in  examining  the  soundness  both  of  new  and  old 
forgings. 

When  a  piece  of  forged  work  is  required  to  be  particularly 
sound,  it  is  a  common  practice  to  subject  every  part  of  the  ma- 
terial in  succession  to  a  welding  heat,  and  to  work  it  well  under 
the  hammer,  as  a  repetition  of  the  process  of  manufacture  to  in- 
sure the  perfection  of  the  iron ;  this  is  technically  called  taking 
a  heat  over  it — in  fact,  a  heat  is  generally  understood  to  imply  the 
welding  heat.  For  a  two-inch  shaft  of  the  soundest  quality,  two 
and  a  half  inch  iron  would  be  selected,  to  allow  for  the  reduction 
in  the  fire  and  the  lathe.  Some  also  twist  the  iron  before  the  ham- 
mering to  prevent  it  from  becoming  "  spilty" 

The  use  of  sand  sprinkled  upon  the  iron  is  to  preserve  it  from 
absolute  contact  with  the  air,  which  would  cause  it  to  waste  away 
from  the  oxidation  of  its  surface,  and  fall  off  in  scales  around  the 
anvil.  If  the  sand  is  thrown  on  when  the  metal  is  only  at  the  full 


ORDINARY   PRACTICE   OF   FORGING.  97 

red  heat  it  falls  off  without  adhering;  but,  when  the  white  heat  is  ap- 
proached, the  sand  begins  to  adhere  to  the  iron ;  it  next  melts  on 
its  surface,  over  which  it  then  runs  like  fluid  glass,  and  defends  it 
from  the  air.  When  this  point  has  been  rather  exceeded,  so  that 
the  metal  nevertheless  begins  to  burn  with  vivid  sparks  and  a 
hissing  noise  like  fireworks,  the  welding  temperature  is  arrived  at, 
and  which  should  not  be  exceeded.  The  sparks  are,  however, 
considered  a  sign  of  a  dirty  fire  or  bad  iron,  as  the  purer  the  iron 
the  less  it  is  subject  to  waste  or  oxidation,  in  the  course  of  work. 

In  welding  two  pieces  of  iron  together,  care  must  be  taken  that 
loth  arrive  at  the  welding  heat  at  the  same  moment ;  it  may  be 
necessary  to  keep  one  of  the  pieces  a  little  on  one  side  of  the  most 
intense  part  of  the  fire  (which  is  just  opposite  the  blast),  should 
the  one  be  in  advance  of  the  other.  In  all  cases,  a  certain  amount 
of  time  is  essential,  otherwise,  if  the  fire  be  unnecessarily  urged, 
the  outer  case  of  the  iron  may  be  at  the  point  of  ignition  before 
the  centre  has  exceeded  the  red  heat.  In  welding  iron  to  steel, 
the  latter  must  be  heated  in  a  considerably  less  degree  than  the 
iron,  the  welding  heat  of  steel  being  lower  from  its  greater  fusi- 
bility. But  the  process  of  welding  will  be  separately  considered 
under  a  few  of  its  most  general  applications,  when  the  ordinary 
practice  of  forging  has  been  discussed,  and  to  which  we  will  now 
proceed. 


ORDINARY  PRACTICE  OF   FORGING. 

THE  general  practices  of  forging  works  from  the  bar  of  iron  or 
steel  are,  for  the  most  part,  included  in  the  three  following  modes ; 
the  first  two  occur  in  almost  every  case,  and  frequently  all  three 
together,  namely : 

By  drawing-down,  or  reduction ; 

By  jumping,  or  up-setting ;  otherwise,  thickening  and  shortening;. 

By  building-up,  or  welding. 

When  it  is  desired  to  reduce  the  general  thickness  of  the  object, 
both  in  length  and  width,  then  the  flat  face  of  the  hammer  is  made 
to  fall  level  upon  the  work;  but,  where  the  length  or  breadth 
alone  is  to  be  extended,  the  pane  or  narrow  edge  of  the  hammer 
is  first  used,  and  its  blows  are  directed  at  the  right  angles  to  the 
direction  in  which  the  iron  is  to  be  spread.  To  meet  the  variety 
of  cases  which  occur,  the  smith  has  hammers  in  which  the  panes 
are  made  in  different  ways — either  at  right  angles  to  the  handle, 
parallel  with  the  same,  or  oblique. 

In  order  to  obtain  the  same  results  with  more  precision  and 
effect,  tools  of  the  same  characters,  but  which  are  struck  with  the 
7 


98  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

sledge-hammer,  are  also  commonly  used.  Those  with  flat  faces 
are  made  like  hammers,  and  usually  with  similar  handles,  except 
that,  for  the  convenience  of  reversing  them,  they  are  not  wedged 
in ;  these  are  called  set-hammers ;  others,  which  have  very  broad 
faces,  are  called  flatters ;  and  the  top  tools,  with  narrow  round 
edges  like  the  pane  of  the  hammer,  are  called  top-fullers.  They 
all  have  the  ordinary  hazel  rods. 

When  the  sides  of  the  object  are  required  to  be  parallel,  and  it 
is  to  be  reduced  both  in  width  and  thickness,  the  flat  face  of  the 
hammer  is  made  to  fall  parallel  with  the  anvil,  as  represented  in 
Fig.  43,  or  oblique,  for  producing  taper  pieces,  as  in  Fig.  44,  and, 
action  and  reaction  being  equal,  the  lower  face  of  the  work  re- 
ceives the  same  absolute  blow  from  the  anvil  as  that  applied 
above  by  the  hammer  itself.  It  is  not  requisite,  therefore,  to  pre- 
sent every  one  of  the  four  sides  to  the  hammer,  but  any  two  at 
right  angles  to  each  other.  This  is  only  true  for  works  of  moderate 
dimensions ;  in  large  masses,  such  as  anchors,  the  soft  doughy  state 
of  the  metal  acts  as  a  cushion,  and  greatly  lessens  the  recoil  of  the 
anvil,  and  on  this  account  such  works  are  presented  to  the  ham- 
mer on  all  four  sides.  It  is  also  very  injudicious  in  such  cases  to 
continue  the  exterior  finish,  or  lattering-off,  too  long,  as  this  ex- 
tends the  outer  case  of  the  metal  more  than  the  inner  part,  and 
sometimes  separates  the  two.  When  imperfect  forgings  are 
broken  in  the  act  of  being  proved,  the  inner  bars  are  sometimes 
found  not  to  be  even  welded  together,  and  the  outside  part  is  a 
detached  sheath,  almost  like  the  rind  or  bark  of  a  tree. 

In  twisting  the  work  round  the  quarter  circle,  some  practice  is 
called  for,  in  order  to  retain  the  rectangular  section,  and  not  to 
allow  it  to  degenerate  into  the  lozenge  or  rhomboidal  form,  which 
error  it  is  difficult  to  retrace. 

«•  This  indeed  may  be  considered  the  first  stumbling-block  in 
forging,  and  one  for  which  it  is  difficult  to  provide  written  rules. 
Of  course  in  converting  a  round  bar  into  a  square  with  the  ham- 
mer, the  accuracy  will  depend  almost  entirely  upon  the  change 
of  exactly  ninety  degrees  being  given  to  the  work,  and  this  the 
experienced  smith  will  accomplish  with  that  same  degree  of  feeling, 
or  intuition,  which  teaches  the  exact  distances  required  upon  the 
finger-board  of  a  violin,  which  is  defined  by  habit  alone. 

In  the  original  manufacture  of  the  iron,  the  carefully  turned 
grooves,  «,  b,  c,  of  the  rollers,  page  81,  produce  the  square  figure 
with  great  truth  and  facility ;  and  under  the  tilt-hammer  the  two 
opposite  sides  are  sure  to  be  parallel,  from  the  respective  parallel- 
ism of  the  faces  of  the  hammer  and  anvil;  and  the  tietrs,  from 
constant  practice,  apply  the  work  with  great  truth  in  its  second 
position.  So  that  under  ordinary  circumstances  the  prepared  ma- 
terials are  true  and  square,  and  the  smith  has  principally  to  avoid 
losing  that  accuracy. 

First,  he  must  acquire  the  habit  of  feeling  when  the  bar  lies  per- 
fectly flat  upon  the  anvil,  by  holding  it  slenderly,  leaving  it  almost 


ORDINARY   PRACTICE   OF   FORGING. 


99 


to  rotate  in  his  grasp,  or  in  fact  to  place  itself.  Next,  he  must 
cause  the  hammer  to  fall  flat  upon  the  work ;  with  which  view  he 
will  neither  grasp  its  handle  close  against  the  head  of  the  hammer, 
nor  at  the  extreme  end  of  the  handle,  but  at  that  intermediate 
point  where  he  finds  it  comfortably  to  rebound  from  the  anvil, 
with  the  least  effort  of,  or  jar  to  his  wrist.  And  the  height  of  the 
wrist  must  also  be  such  as  not  to  allow  either  the  front  or  back 
edge  of  the  hammer-face  to  strike  the  work  first,  which  would  in- 
dent it,  but  it  must  fall  fair  and  parallel,  and  without  bruising  the 


work. 


Figs.  43. 


44. 


45. 


It  would  be  desirable  practice  to  hammer  a  bar  of  cold  iron,  or 
still  better  one  of  steel,  as  there  would  be  more  leisure  for  obser- 
vation, the  indentations  of  the  hammer  could  be  easily  noticed ; 
and  if  the  work,  especially  steel,  were  held  too  tightly,  or  without 
resting  fairly  on  the  anvil,  it  would  indicate  the  error  by  addi- 
tional noise  and  by  jarring  the  wrist ;  whereas,  when  hot,  the  false 
blows  or  positions  would  cause  the  work  to  get  out  of  shape,  with- 
out such  indications. 

As  to  the  best  form  of  the  hammer,  there  is  much  of  habit  and 
something  of  fancy.  The  ordinary  hand-hammer  is  represented  in 
Figs.  43  and  4-i,  but  most  tool  makers  prefer  the  hammer  without 
a  pane,  and  with  the  handle  quite  at  the  top,  the  two  forming 
almost  a  right  angle,  or  from  that  to  about  eighty  degrees ;  and 
sometimes  the  head  is  bent  like  a  portion  of  a  circle.  Similar  but 
much  heavier  hand-hammers,  Occasionally  of  the  weight  of  twelve 
or  fourteen  pounds,  are  used  by  the  spade-makers  for  planishing ; 
but  the  work  being  thin  and  cold,  the  hammer  rises  almost  ex- 
o/usively  by  the  reaction,  and  requires  little  more  than  guidance. 
Again,  the  farriers  prefer  for  some  parts  of  their  work,  a  hammer 
the  head  of  which  is  almost  a  sphere ;  it  has  two  flat  faces,  one 
rounded  face  for  the  inside  of  the  shoe,  and  one  very  stunted  pane 
at  right  angles  to  the  handle,  used  for  drawing  down  the  clip  in 
front  of  the  horse-shoe ;  in  fact,  nearly  a  small  volume  might  be 
written  upon  all  the  varieties  of  hammers. 

To  return  to  the  forging :  the  flat  face  of  the  hammer  should  not 
only  fall  flat,  but  also  centrally  upon  the  work ;  that  is,  the  centre 
of  the  hammer,  in  which  point  the  principal  force  of  the  blow  is 
concentrated,  should  fall  on  the  centre  of  the  bar  otherwise  that 
edge  of  the  work  to  which  the  hammer  might  lean  would  be  the 
more  reduced,  and  consequently  the  parallelism  of  the  work  would 


100  THE   PRACTICAL   METAL- WORKER'S   ASSISTANT. 

be  lost.  It  would  also  be  bent  in  respect  to  length,  as  the  thinned 
edge  would  become  more  elongated,  and  thence  convex;  and  when 
the  blows  were  irregularly  scattered,  the  work  would  become 
twisted  or  put  in  winding,  which  would  be  a  still  worse  error. 

I  will  suppose  it  required  to  draw  down  (the  technical  term  for 
reduction),  six  inches  of  the  end  of  a  square  or  rectangular  bar  of 
iron  or  steel ;  the  smith  will  place  the  bar  across  the  anvil  with 
perhaps  four  inches  overhanging,  and  not  resting  quite  flat,  but 
tilted  up  about  a  quarter  or  half  an  inch  at  the  near  side  of  the 
anvil,  as  in  Fig.  44,  but  less  in  degree,  and  the  hammer  will  be 
made  to  fall  as  there  shown,  except  that  it  will  be  at  a  very  small 
angle  with  the  anvil. 

Having  given  one  blow,  he  will  as  the  only  change,  twist  the 
work  a  quarter  turn,  and  strike  it  again ;  then  he  will  draw  the 
bar  half  an  inch  or  an  inch  towards  him,  and  give  it  two  more 
similar  blows,  and  so  on  until  he  arrives  at  the  extreme  end,  when 
he  will  recommence ;  but  this  will  be  done  almost  in  the  time  of 
reading  these  words.  The  descent  of  the  hammer,  the  drawing  the 
work  towards  himself  (whence  perhaps  the  term),  and  the  quarter 
turn  backwards  and  forwards,  all  go  on  simultaneously  and  with 
some  expedition.  At  other  times  the  work  is  drawn  down  over 
the  beak  iron,  in  which  case  the  curvature  of  this  part  of  the  anvil 
makes  it  less  material  at  what  angle  the  work  is  held  or  the  blows 
given,  provided  the  two  positions  be  alike. 

In  smoothing  off  the  work,  the  position  of  Fig.  43  is  assumed ; 
the  work  is  laid  flat  upon  the  anvil,  and  the  hammer  is  made  to 
fall  as  nearly  as  possible  horizontally ;  a  series  of  blows  are  given 
all  along  the  work  between  every  quarter  turn,  the  hammer 
being  directed  upon  one  spot,  and  the  work  drawn  gradually  be- 
^neath  it. 

The  circumstances  are  exactly  the  same  as  regards  the  sledge- 
hammer, which  is  used  up-hand  for  light  work  ;  the  right  hand  be- 
ing slid  towards  the  head  in  the  act  of  lifting  the  hammer  from  off 
the  work,  and  slipped  down  again  as  the  tool  descends ;  and  the 
conditions  are  scarcely  altered  when  the  smith  swings  the  hammer 
about  in  a  circle,  the  signal  for  which  is  "  about  sledge ;"  whereas 
when,  in  either  case,  the  blows  of  the  sledge  hammer  are  to  be  dis- 
continued, the  fireman  taps  the  anvil  with  his  hand-hammer, 
which  is,  I  believe,  an  universal  language. 

In  drawing  down  the  tang  or  taper-point  of  a  tool,  the  extreme 
end  of  the  iron  or  steel  is  placed  a  little  beyond  the  edge  of  the 
anvil,  as  in  Fig.  44  by  which  means  the  risk  of  indenting  the 
anvil  is  entirely  removed,  and  the  small  irregular  piece  in  excess 
beyond  the  taper  is  not  cut  off  until  the  tang  is  completed.  Fig. 
45  shows  the  position  of  the  chisel  in  cutting  off  the  finished  ob- 
ject from  the  bar  of  which  it  formed  a  part;  that  is,  the  work  is 
placed  betwixt  the  edge  of  the  anvil,  and  that  of  the  chisel  imme- 
diately above  the  same ;  the  two  resemble  in  effect  a  pair  of  shears. 
Sometimes  the  edge  of  the  anvil  alone  is  used  for  small  objects, 


ORDINARY   PRACTICE   OF    FORGING. 


101 


first  to  indent,  and  then  to  break  off  the  work,  but  this  is  likely 
to  injure  the  anvil,  and  is  a  bad  practice. 

When  it  is  required  to  make  a  set-off,  it  is  done  by  placing  the 
intended  shoulder  at  the  edge  of  the  anvil :  the  blows  of  the  ham- 
mer will  be  effective  only  where  opposed  to  the  anvil,  but  the  re- 
mainder of  the  bar  will  retain  its  full  size  and  sink  down,  as  repre- 
sented in  Fig.  46.  Should  it  be  necessary  to  make  a  shoulder  on 


Figs.  4G 


48. 


o 


both  sides,  a  flat-ended  set  hammer,  struck  by  the  sledge,  is  used 
for  setting  do*wn  the  upper  shoulder,  as  in  Fig.  47,  as  the  direct 
blows  of  the  hammer  could  not  be  given  with  so  much  precision. 
In  each  of  these  cases  some  precaution  must  be  observed,  as  other- 
wise the  tools,  although  so  much  more  blunt  than  the  chisel, 
Fig.  45,  will  resemble  it  in  effect,  and  cripple  or  weaken*  the  work 
in  the  corner.  On  this  account  the  smith's  tools  are  rarely  quite 
sharp  at  the  angles.  This  mischief  is  almost  removed  when  the 
round  fullers,  Fig.  48,  are  used  for  reducing  the  principal  bulk,  and 
the  sharper  tools  are  only  employed  for  trimming  the  angles  with 
moderate  blows. 

When  the  iron  is  to  be  set  down,  and  also  spread  laterally,  as  in 
Fig.  49,  it  is  first  nicked  with  a  round  fuller  as  upon  the  dotted 
line  at  a,  and  the  piece  at  the  end  is  spread  by  the  same  tool,  upon 

a  Fig.  49. 


the  short  lines  of  the  object,  or  parallel  with  the  length  of  the  bar. 
The  first  notch  greatly  assists  in  keeping  a  good  shoulder  at  the 
bottom  of  the  part  set  down,  and  the  lines  are  supposed  to  repre- 
sent the  rough  indications  of  the  round  fuller  before  the  work  is 
trimmed  up. 

There  is  often  considerable  choice  of  method  in  forging,  and  the 
skillful  workman  selects  that  method  of  proceeding  which  will  pro- 
duce the  result  with  the  least  portion  of  manual  labor.  Thus  an 
ordinary  screw-bolt,  that  I  will  suppose  to  measure  five-eighths  of 
an  inch  in  diameter  in  the  stem,  and  one  inch  square  in  the  head, 
may  be  made  in  either  of  the  three  following  ways  adverted  to  in 
the  outset: 


102 


THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 


First,  by  drawing-down : — A  bar  of  iron  is  selected  one  inch 
square,  or  of  the  size  of  the  head  of  the  bolt,  and  a  short  portion 
of  the  same  is  set  down,  according  to  Fig.  48,  by  a  pair  of  fullers 
that  are  convex  in  profile  as  shown,  and  also  slightly  concave  upon 
the  line  at  right  angles  to  the  paper.  This  prepares  the  shoulder 
or  joining  of  the  two  dimensions.  The  bolt  is  made  cylindrical, 
and  of  proper  diameter  between  the  rounding  tools,  Fig.  50 ;  and 
lastly,  it  is  cut  off  with  the  chisel,  as  in  Fig.  45,  so  much  of  the 
original  square  bar  as  suffices  for  the  thickness  of  the  head  being 
allowed  to  remain. 

Secondly,  by  jumping : — A  piece  of  bolt-iron  of  five-eighths  of 
an  inch  in  diameter,  or  of  the  size  of  the  stem  of  the  bolt,  is  cut 
off  somewhat  longer  than  the  intended  length:  "a  short  heat"  is 
taken  upon  it,  that  is,  the  extreme  end  alone  is  made  white-hot, 
then  placed  perpendicularly  upon  .the  anvil,  and  the  cold  end  is 
struck  with  the  hammer  as  in  driving  in  a  nail.  This  thickens 
the  metal  or  upsets  it,  and  makes  a  thick  conical  button.  The 
head  is  completed  by  driving  the  bolt  into  a  heading  tool  with  a 
circular  hole  of  five-eighths  diameter.  The  thickened  part  of  the 
head  prevents  the  piece  from  passing  through,  and  the  lump  is 
flattened  out  by  the  hammer  into  an  irregular  button  or  disk,  which 
is  afterwards  beaten  square  to  complete  the  bolt.  Figs.  51,  52,  and 
53,  explain  these  processes.  The  latter  is  a  single  tool,  but  the 
heading  tool,  Fig.  54,  with  several  holes,  is  also  used. 


Figs.  50       53 


52     51 


In  upsetting  the  end  of  the  work,  if  more  convenient,  it  may  be 
held  horizontally  across  the  anvil  and  struck  on  the  heated  ex- 
tremity with  the  hand  hammer;  or  it  can  be  jumped  forcibly  upon 
the  anvil,  when  its  own  weight  will  supply  the  required  momen- 
tum. If  too  considerable  a  portion  of  the  work  is  heated,  it  will 
either  bend,  or  it  will  swell  generally ;  and  therefore  to  limit  the 
enlargement  to  the  required  spot,  should  the  heat  be  too  long,  the 
neighboring  part  is  partially  cooled  by  immersing  it  in  the  water 
trough,  as  near  to  the  heat  as  admissible. 


ORDINARY   PRACTICE   OF   FORGING.  103 

Thirdly,  the  same  bolt  may  be  made  by  building-up  or  welding : 
— An  eye  is  first  made  at  the  end  of  a  small  rod  of  square  or  flat 
iron  ;  by  bending  it  round  the  beak  iron,  as  in  Fig.  55,  it  is  placed 
around  the  rod  of  five-eighths  round  iron,  and  the  curled  end  is 
cut  off  with  the  chisel,  as  in  Fig.  56,  enough  iron  being  left  in  the 
ring,  which  is  afterwards  welded  to  the  five-eighths  inch  rod  to 
form  the  head  of  the  bolt,  by  a  few  quick  light  blows  given  at  the 
proper  heat.  The  bolt  is  then  completed  by  any  of  the  tools  already 
described  that  may  be  preferred.  A  swage  at  the  angle  of  sixty 
degrees,  Fig.  57,  will  be  found  very  convenient  in  forming  hex- 
agonal heads,  as  the  horizontal  blow  of  the  hammer  completes  the 
equilateral  triangle,  and  two  positions  operate  on  every  side  of  the 
hexagon ;  Fig.  57  is  essential  likewise  in  forging  triangular  files 
and  rods. 

Of  these  three  modes  of  making  a  bolt,  and  which  will  apply  to 
a  multitude  of  objects  somewhat  analogous  in  form,  the  first  is  the 
most  general  for  small  and  short  bolts ;  the  second  for  small  but 
longer  kinds ;  and  the  third  is  perhaps  the  most  common  for  large 
bolts,  although  the  least  secure ;  it  is  used  for  bolts  for  ordinary 
building  purposes,  but  is  less  generally  employed  for  the  parts  of 
mechanism. 

For  works  of  the  same  character,  in  which  a  considerable  length 
of  two  different  sections  or  magnitudes  of  iron  are  required,  the 
method  by  drawing  down  from  the  large  size  would  be  too  expen- 
sive ;  the  method  by  upsetting  would  be  impracticable ;  and  there- 
fore a  more  judicious  use  is  made  of  the  iron  store,  and  the  object 
is  made  in  two  parts,  of  bars  of  the  exact  sections  respectively. 
The  larger  bar  is  reduced  to  the  size  of  the  smaller,  generally  upon 
the  beak  iron  with  top  fullers,  and  with  a  gradual  transition  or 
taper  extending  some  few  inches,  as  represented  in  Fig.  58 ;  the 
two  pieces  are  scarfed  or  prepared  for  welding,  but.  which  part  of 
the  subject- is  for  the  present  deferred,  in  order  that  the  different 
examples  of  welding  may  be  given  together. 

The  Fig.  58  is  also  intended  to  explain  two  other  proceedings 
very  commonly  required  in  forging.  Bars  are  bent  down  at  right 
angles  as  for  the  short  end  or  corking  of  the  piece,  Fig.  58,  by  lay- 
ing the  work  on  the  anvil,  and  holding  it  down  with  the  sledge- 
hammer, as  in  Fig.  59  ;  the  end  is  then  bent  with  the  hand-hammer, 
and  trimmed  square  over  the  edge  of  the  anvil ;  or  when  more  pre- 
cision is  wanted,  the  work  is  screwed  fast  in  fie  tail- vice,  which  is 
one  of  the  tools  of  every  smith's  shop,  and  it  is  bent  over  the  jaws 
of  the  vice.  When  the  external  angle,  as  well  as  the  internal,  is 
required  to  be  sharp  and  square,  the  work  is  reduced  with  the 
fuller  from  a  larger  bar  to  the  form  of  Fig.  60,  to  compensate  for 
the  great  extension  in  length  that  occurs  at  the  outer  part,  or  heel 
of  the  bend,  of  which  the  inner  angle  forms  as  it  were  the  centre. 

The  holes  in  Fig.  58,  for  the  cross  bolts,  are  made  with  a  rod- 
punch,  which  is  driven  a  little  more  than  half  way  through  from 
the  one  side  whilst  the  work  lies  upon  the  anvil,  so  that  when 


104 


THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 


turned  over,  the  cooling  effect  of  the  punch  may  serve  to  show  the 
place  where  the  tool  must  be  again  applied  for  the  completion  of 
the  hole ;  the  little  bit  or  burr  is  then  driven  out,  either  through 
the  square  hole  in  the  anvil  that  is  intended  for  the  bottom  tools, 
or  else  upon  the  bolster,  Fig.  61,  a  tool  faced  with  steel,  and  having 
an  aperture  of  the  same  form  and  dimensions  as  the  face  of  the 
punch. 


Figs.  59 


64 


65 


Fig.  6-i  shows  the  ordinary  mode  of  making  the  square  nuts  for 
bolts.  A  flat  bar  is  first  nicked  on  the  sides  with  the  chisel,  then 
punched,  and  the  rough  nuts  if  small,  are  separated  and  strung 
upon  the  end  of  the  poker  (a  slight  round  rod  bent  up  at  the  end), 
for  the  convenience  of  managing  them  in  the  fire,  from  which  they 
are  removed  one  at  a  time  when  hot,  and  finished  on  the  triblet, 
Fig.  65,  which  serves  both  as  a  handle,  and  also  as  the  means  of 
perfecting  the  holes. 

For  making  hexagon  nuts,  the  flat  bar  is  nicked  on  both  edges 
with  a  narrow  round  fuller ;  this  gives  a  nearer  approach  to  the 
hexagon:  the  nuts  are  then  flattened  on  the  face,  punched,  and 
dressed  on  the  triblet  within  the  angular  swage,  Fig.  57,  before 
adverted  to.  Thick  circular  collars  are  made  precisely  in  the  same 
way,  with  the  exception  that  they  are  finished  externally  with  the 
hammer,  or  between  top  and  bottom  rounding  tools  of  correspond- 
ing diameter. 

It  is  usual  in  punching  holes  through  thick  pieces,  to  throw  a 
little  coal-dust  into  tfie  hole  when  it  is  partly  made,  to  prevent  the 
punch  sticking  in  so  fast  as  it  otherwise  would :  the  punch  generally 
gets  red-hot  in  the  process,  and  requires  to  be  immediately  cooled 
on  removal  from  the  hole. 

In  making  a  socket,  or  a  very  deep  hole  in  the  one  end  of  a  bar, 
some  difficulty  is  experienced  in  getting  the  hole  in  the  axis  of  the 
bar,  and  in  avoiding  to  burst  open  the  iron ;  such  holes  are  pro- 
duced differently,  by  sinking  the  hole  as  a  groove  in  the  centre  of 
a  flat  bar  by  means  of  a  fuller ;  the  piece  is  cut  nearly  through  from 
the  opposite  side,  folded  together  lengthways,  and  welded.  The 


ORDINARY  PRACTICE   OF  FORGING.  105 

hole  thus  formed  will  only  require  to  be  perfected  by  the  introduc- 
tion of  an  appropriate  punch,  and  to  be  worked  on  the  outside,  with 
those  tools  required  for  dressing  off  its  exterior  surface,  whilst  the 
punch  remains  in  the  hole  to  prevent  its  sides  from  being  squeezed 
in  :  this  method  is  very  good. 

For  punching  square  holes,  square  punches  and  bolsters  are 
used,  and  Fig.  62,  the  split  bolster,  is  employed  for  cutting  out 
long  rectangular  holes  or  mortises,  which  are  often  done  at  two  or 
more  cuts  with  an  oblong  punch. 

Mortises,  when  of  still  greater  length,  are  usually  made  by  punch- 
ing a  hole  of  their  full  width  at  each  end,  and  cutting  out  a  strip 
of  metal  between  them,  by  two  long  incisions  made  with  the  rod- 
•  •hisel;  at  other  times  one  cut  only  is  made,  and  the  mortise  is 
opened  out ;  this  retains  all  the  iron,  but  makes  the  ends  narrower 
than  the  middle.  In  finishing  a  mortise,  a  parallel  plate  or  drift  is 
inserted  in  the  slit ;  the  drift  is  laid  across  the  chaps  of  the  vice, 
whilst  the  bar  of  iron  lies  partly  between  its  jaws,  in  order  that  the 
blows  of  the  hammer  may  be*  effective,  on  the  upper  and  under 
surfaces  of  the  one  rib  at  the  same  time.  The  drift  serves  as  a 
temporary  anvil ;  the  other  rib  is  completed  in  the  same  manner, 
and  the  work  is  finally  closed  to  its  true  width  upon  the  anvil,  the 
drift  still  lying  in  the  mortise. 

When  a  thick  lump  is  wanted  at  the  end  of  a  bar,  it  is  often 
made  by  cutting  the  iron  nearly  through  and  doubling  it  backwards 
and  forwards,  as  in  Fig.  63 ;  the  whole  is  then  welded  into  a  solid 
mass  as  the  preparatory  step. 

Fig.  66.  Fig.  67. 


A  piece  with  three  tails,  such  as  Fig.  66,  is  made  from  a  large 
square  bar ;  an  elliptical  hole  is  first  punched  through  the  bar,  and 
the  remainder  is  split  with  a  chisel,  as  in  Fig.  67,  the  work  at  the 
time  being  laid  upon  a  soft  iron  cutting  plate  in  order  to  shield  the 
chisel  from  being  driven  against  the  hardened  steel  face  of  the  an- 
vil ;  the  end  is  afterwards  opened  into  a  fork,  and  moulded  into 
shape  over  the  beak-iron,  as  indicated  by  the  dotted  lines. 

The  concave  lines  about  the  object  are  principally  worked  with 
the  fuller,  or  half-round  set-hammer ;  and  in  making  all  the  holes, 
narrow  oval  punches  are  used  as  described  at  the  commencement, 
and  the  slits  are  enlarged  into  circular  holes  by  conical  mandrels  ; 
these  bulge  the  metal  out,  and  the  holes  arc  more  judiciously  formed 
in  this  manner  than  if  the  metal  were  wasted  by  cutting  out  great 
circular  holes,  which  would  sever  a  large  quantity  of  the  fibres  and 
reduce  the  strength 


106  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

The*  mandrels  are  left  in  the  holes  whilst  the  parts  around  them 
are  finished,  which  tends  to  the  perfection  of  both  parts ;  as  the 
holes  more  closely  copy  the  mandrels,  and  the  marginal  parts  are 
better  finished  when  the  apertures  are  for  the  time  rendered  solid. 
Supposing  a  hole  to  be  wanted  in  the  cylindrical  part  of  the  work 
that  should  be  finished  between  the  rounding  tools,  the  mandrel 
could  not  be  allowed  to  remain  in ;  and  therefore  a  short  piece  of 
iron  is  forged  or  drawn  down  to  the  size  of  the  hole,  cut  off  in  length 
to  the  diameter  of  the  part,  and  inserted  in  the  hole  to  preserve  it 
from  being  compressed,  yet  without  interference  with  the  completion 
of  the  cylindrical  portion;  which  accomplished,  this  little  bit,  called 
by  the  un-mechanical  name  of  a  devil,  is  driven  out,  unless  by  a 
very  careless  use  of  the  welding  temperature  it  should  have  been 
permanently  fastened  in.  Towards  the  conclusion  a  long  mandrel 
is  passed  through  the  two  holes  in  the  fork  of  Fig.  66,  to  show 
whether  their  common  axis  is  at  right  angles  to  the  main  rod, 
otherwise  the  one  or  other  arm  is  drawn  out,  or  upset,  accord- 
ing as  the  work  may  err  in  respect  to  deficiency  or  excess  of 
length.  Such  a  piece  as  Fig.  66,  if  of  large  dimensions,  would  be 
made  in  two  sep'arate  parts,  and  welded  through  the  central  line 
or  axis. 

Should  it  happen  the  two  arms  are  not  quite  parallel,  that  is, 
when  viewed  edgeways  should  they  stand  oblique  to  each  other,  or 
to  the  central  bar,  an  error  that  could  scarcely  be  corrected  by  the 
hammer  alone ;  the  work  would  be  fixed  in  the  vice  with  the  two 
tails  upwards,  and  the  one  or  other  of  these  would  be  twisted  to  its 
true  position  by  a  hook  wrench  or  set,  made  like  the  three  sides  of  a 
square,  but  the  one  very  long  to  serve  as  a  lever ;  it  is  applied 
exactly  in  the  manner  of  a  key,  spanner,  or  screw  wrench,  in  turn- 
ing round  a  bolt  or  screw.  The  hook  'wrench  is  constantly  used 
for  taking  the  twist  out  of  work,  or  the  error  of  winding,  as  the 
hammer  can  only  be  successfully  employed  for  correcting  the  cur- 
vatures of  length. 

Some  bent  objects,  such  as  cranks  and  straps,  are  made  from  bar- 
iron,  bent  over  specific  moulds,  which  are  sometimes  made  in  pairs 
like  dies,  and  pressed  together  by  screw  contrivances.  When  the 
moulds  are  single,  the  work  is  often  retained  in  contact  with  the 
same,  at  some  appropriate  part,  by  means  of  straps  and  wedges ; 
whilst  the  work  is  bent  to  the  form  of  the  mould  by  top  tools  of 
suitable  kinds. 

Objects  of  more  nearly  rectilinear  form  are  cut  out  of  large  plates 
and  bars  of  iron  with  chisels ;  for  example,  the  cranks  of  locomotive 
engines  are  faggoted  up  of  several  bars  or  uses  laid  together,  and 
pared  to  the  shape ;  they  are  sometimes  forged  in  two  separate 
parts,  and  welded  between  the  cranks,  at  other  times  they  are  forged 
out  of  one  parallel  mass,  and  afterwards  twisted  with  a  hook- wrench, 
in  the  neck  between  the  cranks,  to  place  the  latter  at  right  angles. 
The  notches  are  sometimes  cut  out  on  the  anvil  whilst  the  work  is 
red-hot ;  or  otherwise  bv  machinery  when  in  the  cold  state. 


ON   WROUGHT-IRON   IN    LARGE    MASSES.  107 

A  very  different  method  of  making  rectangular  cranks  and 
similar  works  is  also  recommended,  by  bending  one  or  more  straight 
bars  of  iron  to  the  form,  the  angles,  which  are  at  first  rounded,  are 
perfected  by  welding  on  outer  caps.  In  this  case  the  fibre  runs 
round  the  figure,  whereas  when  the  gap  is  cut  out,  a  large  propor- 
tion of  the  fibres  are  cut  into  short  lengths,  and  therefore  a  greater 
bulk  must  be  allowed  for  equal  strength :  this  method  is  however 
seldom  used. 

All  kinds  of  levers,  -arms,  brackets  and  frames,  are  made  after 
these  several  methods,  partly  by  bending  and  welding,  and  partly 
by  cutting  and  punching  out;  and  few  branches  of  industry  pre- 
sent a  greater  variety  in  the  choice  of  methods,  and  which  call  the 
j  udgment  of  the  smith  continually  into  requisition. 


CHAPTER  VII. 

ON   WROUGHT-IRON   IN   LARGE   MASSES. 

THE  manufacture  of  wrought-iron  in  large  masses  cannot  boast 
of  a  very  early  origin.  Although  we  read  in  the  most  ancient  of 
Books  that  Tubal  Cain,  before  the  Flood,  was  an  instructor  of 
every  artificer  in  brass  and  iron,  it  would  doubtless  have  puzzled 
even  that  great  founder  of  the  iron  trade,  had  he  been  furnished 
with  an  order  to  make  the  large  masses  of  wrought-iron  required 
for  a  "Niagara,"  "New  Ironsides,"  "Roanoke,"  or  "Great  Eastern" 
steam-ship ;  and  he  would  have  been  equally  at  a  loss  with  many 
modern  craftsmen,  had  he  been  requested  to  forge  a  monster  gun 
or  a  double-throw  crank-shaft  for  engines  of  1000  horse-power. 
Were  he  again  permitted  to  visit  the  world,  the  mighty  machinery 
at  work  on  every  hand  would  compel  the  admission  that  his  trade 
had  made  great  strides  during  his  absence.  These  advances  in 
the  manufacture  of  wrought-iron  in  large  masses  have  taken  place 
almost  entirely  within  the  present  century,  if  not,  indeed,  within 
the  last  thirty  years.  Up  to  that  period,  the  improvements  upon 
Tubal  Cain's  (we  presume  original)  inventions  were  of  so  limited  u 
nature,  that,  in  the  year  1820,  the  manufacture  of  a  shaft — say  of 
about  6  inches  diameter,  and  weighing  15  or  20  cwt. — required  the 
concentrated  exertions  of  a  large  establishment,  and  was  considered 
a  vast  triumph  if  successfully  accomplished ;  whereas  we  are  now 
accustomed  to  forgings  of  20  and  30  tons'  weight,  as  matters  of 
every-day  occurrence,  scarcely  exciting  the  slightest  notice.  Nor 
do  we  stop  even  here :  much  larger  masses  will  no  doubt,  ere  long, 
be  manufactured  for  the  construction  of  iron  ships,  which  in  future 
years,  owing  to  the  increased  size  and  strength  of  the  plates,  will 
be  built  upon  a  scale  that  would  but  recently  have  been  deemed 


108 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT, 


fabulous.  This  consideration,  combined  with  the  requirements  of 
rapid  communication,  which  demand  more  colossal  engines,  call 
for  renewed  energy  in  conducting  this  important  manufacture. 

It  may,  perhaps,  not  be  out  of  place  to  mention  here,  as  a  fact 
having  few  parallels  in  other  branches  of  the  industrial  arts,  that, 
almost  without  exception,  all  the  improvements  that  have  latterly 
crowded  upon  each  other  in  this  trade  have  originated  with  the 
"hammermen"  or  workmen  themselves,  and  have  been  worked 
without  even  the  protection  of  an  exclusive 
patent- right. 

Our  subject  naturally  divides  itself  into  two 
chief  heads,  viz.,  the  materials  of  which  forgings 
are  made,  and  the  tools  with  which  the  manu- 
facture is  accomplished.  We  purpose  treating 
of  the  latter  first. 

DESCRIPTION  OF  FORGE-TOOLS. — A  forge  has 
necessarily  three   principal   divisions,  viz.,  the 
furnace,  the  crane,  and  the  hammer ;  and  they 
compose  the  chief  fixtures.     The  furnace  (Fig. 
68)  is,  in  this  country,  of  the  ordinary  reverberat- 
ing description,  strongly  bound  together  with 
plates  and  binders  of  iron,  of  a  proportionate  size 
to  the  description  of  work  intended  to  be  per- 
formed.   A  very  great  deal  more  depends  upon 
the  furnace  than  might  be  supposed  by  those 
who  are  not  thoroughly  conversant  with  the 
practical  working  of  one.     Variations   in   the 
slightest  detail  in  their  construction 
or  working  are  followed  by  such 
great  differences  in  the  results,  that 
even  a  good  and  experienced  fur- 
naceman,  if  set  to  manage  a  strange 


Fig.  63. 


ON  WROUGHT-IRON  IN   LARGE   MASSES.  109 

furnace,  will  find  some  difficulty  until  he  lias  made  himself  thoroughly 
acquainted  with  its  peculiarities. 

The  selection  of  a  proper  description  of  fire-brick  with  which  to 
construct  the  furnace  is  a  matter  of  considerable  importance.  With- 
out attempting  to  enter  into  the  merits  of  different  fire-bricks,  we 
would  observe  that  the  question  of  expense  is  infinitesimal  when 
compared  with  the  consequences  of  using  cheap  and  inferior  bricks, 
which  would  be  costly  at  the  lowest  price,  from  the  great  wear  and 
tear  upon  them,  and  from  the  annoyance  and  loss  caused  by  the 
often-repeated  stoppages  for  repairs.  It  is,  therefore,  the  wisest 
and  best  economy  always  to  use  the  very  best  fire-bricks  that 
money  can  procure.  In  some  cases  where  large  work  is  intended 
to  be  made,  a  furnace,  with  a  grate  at  each  end,  and  having  the 
.«tack  or  chimney  in  the  centre,  has  been  tried;  but,  as  it  has  not 
been  generally  introduced,  we  presume  it  possesses  few,  if  any,  ad- 
vantages over  the  ordinary  furnace.  In  fact,  for  the  largest  forg- 
ings  that  have  ever  been  made,  furnaces  with  single  grates  have 
proved  successful,  where  double-grated  furnaces  have  failed.  The 
sketch  we  have  given  in  Fig.  68  is  a  furnace  such  as  is  gener- 
ally used,  and  which  is  found  very  effective  for  the  purposes 
required. 

With  anthracite  coal,  furnaces  with  closed  ash-pits,  and  blown 
with  a  fan,  are  used,  and  which  answer  very  well. 

Mr.  Mallet,  in  his  work  on  the  "Construction  of  Artillery," 
page  114,  states,  that  "at  length  the  limit  is  found  when  with  our 
present  known  modes  of  working  wrought-iron  (even  with  the 
heaviest  and  best  appliances)  we  can  no  longer  add  to  its  size. 
The  limit  is  reached  by  the  failure,  of  power  to  heat  the  mass,  or 
the  required  part  of  it,  to  the  welding  heat.  The  time  required 
for  the  piece  to  remain  in  the  furnace  to  effect  this,  continually  in- 
creases as  its  bulk  grows,  and  with  it  the  sources  through  which 
heat  is  lost  and  dissipated;  but  a  certain  proportion  of  iron  is 
burned  away,  or  melted  from  the  surface  at  the  part  requiring  to 
be  brought  to  welding,  as  equals  the  weight  of  the  '  slab'  or  mass 
laid  on,  and  the  labor  is  then  in  vain :  the  work,  like  that  of  the 
embroidery  of  Penelope,  becomes  an  endless  task,  and  the  limit 
has  been  reached  beyond  which  the  piece  can  be  forged  no  bigger. 
The  point  at  which  this  limit  is  reached  can  be  stretched  a  good 
deal  by  the  extreme  skill  of  the  operative  forge  man,  and  the  skil- 
ful construction  of  his  furnace;  but,  however  great  these  may  be, 
the  limit  is  at  length  reached  by  all;  and,  with  our  existing  tools,  in 
Great  Britain  is  probably  reached  in  every  case  at  a  diameter  (of  a 
cylindrical  mass)  of  about  four  feet,  and  about  twenty  feet  m 
length." 

There  is  considerable  truth  and  force  in  these  observations  as 
applied  to  existing  machinery  :  but  the  paragraph  seems  to  con- 
vey the  impression  that  we  are  not  expected  to  exceed  the  limits 
laid  down  by  Mr.  Mullet.  We  should  be  sorry  to  indorse  this 
opinion,  or  to  believe  that  we  have  even  approached  the  maxi- 


110 


THE   PEACTICAL   METAL-WORKER'S  ASSISTANT. 


mum  size  in  our  forgings,  having  so  frequently  and  so  recently 
seen  that  which  is  in  one  year  deemed  impracticable  in  the  manu- 
facture of  forgings^  accomplished  with  the  utmost  ease  in  the  suc- 
ceeding one ;  while  the  necessary  requirements  of  that  year  are 
again  followed  by  still  further  improvements,  even  where  inven- 
tion and  mechanical  skill  had  apparently  reached  their  highest 
development.  And  so  it  will  continue  to  the  end  of  the  chapter. 
"We  might  as  well  attempt  to  obstruct  the  progress  of  the  engi- 
neer, and  say  to  him,  "Thus  far  canst  thou  go,  but  no  farther  "  as 
attempt  to  limit  the  sizes  to  which  forgings  may  be  made  in  future 
years.  If  larger  forgings  are  required,  and  money  is  forthcoming 
to  pay  the  cost  of  their  manufacture,  the  work  will  not  stand  still 
for  the  want  of  workmen  to  undertake  it,  or  machinery  wherewith 
to  handle  it,  however  large  it  may  be.  The  only  real  obstacle  to 
the  production  of  forgings  of  larger  size  is  the  cost ;  the  bugbear 
set  up  in  the  above  extract,  that  more  iron  is  wasted  than  is  added, 
being  but  another  mode  of  accounting  for  inexperience  and  bad 
workmanship. 

CRANE. — The  crane  is  a  very  useful  auxiliary  in  the  working  of 
the  forge.  Without  its  aid  it  would  be  impossible  to  fabricate 
those  large  masses  of  iron,  the  almost  daily  manufacture  of  which 
has  ceased  to  excite  surprise  at  their  magnitude. 

The  crane  (Fig.  69),  as  is  well  known,  is  composed,  first  of  a 

strong  upright,  either  in- 

Flg-  69>  dependency   fixed   in    a 

^  "  solid   foundation   in   the 

ground,  or  dependent  on 
the  walls  or  roof  of  a 
building ;  next,  of  the  top 
pieces,  called  "  cheeks," 
and  the  "  stays,"  to  which 
is  attached  a  winch  of 
ordinary  construction ; 
and  a  strong  pair  of 
blocks,  with  a  chain  lead- 
ing to  the  winch.  It  is 
necessary  that  the  blocks 
should  be  capable  of 
working  backward  and 

_____^ forward    on   the   cheeks, 

which  is  technically  called 

"  racking  out,"  or  "  in,"  from  the  fact  that  a  rack  and  pinion-wheel 
are  generally  employed  to  effect  the  object.  The  crane  must  also 
be  so  placed  that  the  centre  is  exactly  equidistant  from  the  centre 
of  the  furnace-door  and  the  centre  of  the  anvil,  its  use  being  to 
swing  "  the  piece"  from  the  furnace  to  the  anvil,  and  vice  versa. 

Cranes  have  generally  been  made  of  wood,  although  very  few 
sorts  of  wood  are  capable  of  resisting  the  great  heat  to  which 
cranes  for  forging  are  subjected.  Others,  however,  have  lately 


ON   WROUGHT-IRON   IN   LARGE   MASSES. 


Ill 


been  made  of  iron,  or  of  a  mixture  of  iron  and  wood.  Cast-iron, 
being  comparatively  brittle,  is  decidedly  objectionable  and  unsafe, 
in  consequence  of  the  great  weight  they  have  to  bear,  and  the  ex- 
cessive jar  of  the  forge-hammer.  There  is  less  obj ection  to  wrought- 
iron,  which,  if  rightly  proportioned,  is  we  believe  the  best  material 

for  the  purpose. 

HAMMERS.  —  We 
now  come  to  what 
is,  perhaps,  the  most 
important,  or,  at  any 
rate,  what  is  con- 

sidered  the  most  im- 

~"  portant   tool  in  the 

forge,  viz.,  the  hammer ;  and  we  purpose  giving  a  slight  description 
of  the  various  sorts  in  use  at  the  present  time,  including  the  beauti- 
ful direct-acting  tool  known  as  the  Nasmyth  or  steam-hammer. 
We  are  unable,  in  the  limits  of  this  work,  to  consider  the  merits, 
or  give  any  description  of  the  various  improvements  that  have 
been  attempted  on  the  original  steam-hammer ;  some  of  them  being 
confined  to  matters  of  detail,  while  others  introduce  defects  so 
palpable,  that  we  gladly  return  to  the  original  Nasmyth. 

The  most  ancient  form  of  forge-hammer  was  probably  that 
technically  called  the  "  tennant-helve,"  Fig.  70,  known  in  France  as 
the  "  Marteau  frontal."  from  its  being  lifted  at  the  front  end.  This 
hammer  is  a  heavy  mass  of  cast-iron,  which  was  lifted  by  project- 
ing arms,  fixed  in  a  ring  of  iron,  called  the  "cam-ring,"  falling 
through  a  certain  space  by  its  own  gravity.  The  pivots  behind, 
on  which  it  rested,  were  of  a 
curved  form,  to  allow  its  being 


Fig.  71. 


a  similar 


easily  worked.  This  was,  and 
still  is  in  many  works,  a  very 
effective  tool,  performing  its  work 
with  regularity,  and  seldom  get- 
ing  out  of  order. 

The  "  tennant-helves "  being  found  inconvenilnt  for  certain  de- 
scriptions of  work,  the  "  tilt-hammer,"  Fig.  71,  was  introduced.     In- 
stead of  being  raised  at  the  front  end,  this  hammer  is  depressed  by 
«  B;m;i«.  «  cam-ring "  from  a  part  projecting  behind.    It  is  composed 
Fig.  72.  of  wood  and  iron,  the  shank  being  of 

good  tough  oak,  wedged  into  a  ring 
in  which  it  works ;  the  hammer-head 
being  also  wedged  on  to  the  shank. 
The  shank  is  surmounted  by  a  beam 
of  wood,  which,  acting  as  a  powerful 
spring,  gives  greater  force  and  rapidity 
to  the  blow.  This  form  of  hammer 
was  peculiarly  adapted  to  the  "  tilting" 
of  the  different  sorts  of  steel. 
Another  improvement  on  the  original  "tennant-helve/'  was  to 


112 


THE   PRACTICAL    METAL-WORKERS   ASSISTANT. 


lift  the  helve  between  the  head  of  the  hammer  and  the  pivots  on 
which  it  worked  (Fig.  72),  an  advantage  being  thus  given  to  the 
hammerman,  which  the  tilt  also  possesses,  by  enabling  him  to  go 
all  round  the  end  of  his  hammer.  But  the  last  and  greatest  im- 
provement was  that  known  to  the  trade  as  the  "  belly-helve,"  Fig.  73 ; 
a  not  very  euphonious  name,  but  one  which  indicates  the  nature 
of  the  tool.  It  was  lifted,  as  its  name  indicates,  under  the  bottom 

part  of  the  helve,  by 
means*  of  a  "bray?' 
which  could  be  length- 
ened or  shortened  ac- 
cording to  the  size  of 


Fig.  73. 


Fig.  74. 


the  "  piece"  to  be  acted 
upon.  With  some  of 
the  largest  size  a  very 
effectual  blow  is  struck  with  a  piece  of  iron  of  from  3  feet  to  4 
feet  in  diameter  —  the  "helve",  being  raised,  and  the  "bray"  being 
lengthened  in  proportion.  This  hammer  also  permits  the  hammer- 
man to  go  completely  round  his  hammer,  to  inspect  the  work  under 
operation.  For  plain  ordinary  work  it  is  not  surpassed  in  efficiency, 
even  by  the  direct-acting  steam-hammer.  It  is  of  very  great  im- 
portance that  the  foundation  be  perfectly  firm,  and  capable-  of  re- 
sisting the  force  of  the  blows  to  which  it  is  subjected.  The  most 
usual  way  of  securing  this  end,  is  by  placing  under  the  anvil-block 

—  which  of  itself  is 
a  very  massive  cast- 
ing, weighing,  with 
the  cup  upon  which 
it  rests,  from  twelve 
to  fifteen  tons  —  a 
considerable  mass 
of  timber,  carefully 
placed  and  fittecl 
cross-wise.  This 
foundation  must  be 
strongly  secured,  for 
unless  the  anvil- 
block  is  very  firm, 
a  considerable  por- 
tion of  the  blow  will 
be  dissipated,  and 
its  value  lost. 

We  come,  lastly, 
to  Nasmy  th's  steam- 
hammer,  Fig.  74,  a 
nas  de- 


-Tranaar 
servedly  come  into  very  general  use.     Although  many  of  the  very 

largest   forgings   have   been   made   by  the  old-fashioned  helves, 
especially  the  "  belly  -helve  "  above  described;  nevertheless,  the  in- 


ON   WROl'GHT-IRON-   IN   LARGE   MASSES.  113 

vention  has  been  of  immense  importance,  not  only  to  the  forge- 
masters,  but  in  many  other  branches  of  manufacture.  The  steam- 
hammer,  like  other  great  inventions,  has  its  faults  as  well  as  its 
merits.  The  first  great  merit  of  the  steam-hammer  is,  that  it  is  a 
simple  direct-acting  machine,  dispensing  with  much  of  the  cum- 
brous wheel- work  required  with  the  old  helves.  It  takes  up  little 
room,  and  requires  no  "  gagger,"  as  the  attendant  workman  is 
called,  who  attends  to  the  hammer.  The  presence  of  the  "  gagger" 
we  object  to,  not  so  much  on  account  of  the  expense,  which  is 
partly1  counterbalanced,  in  the  case  of  the  steam-hammer,  by  the 
necessity  of  employing  an  engineer ;  but  on  account  of  the  almost 
insufferable  torture  from  heat  which  the  "gagger"  has  to  endure: 
for  if  the  "  gag"  is  not  inserted  and  the  hammer  stopped  at  the 
critical  moment,  a  valuable  piece  of  work  may  be  damaged. 
Another  of  the  excellences  of  the  steam-hammer  is,  that  the  blow 
can  be  varied  according  to  the  size  of  the  "  piece"  under  operation, 
and  the  force  of  the  blow  required.  •  This  is  not,  practically,  such 
a  great  advantage  as  might  at  first  appear ;  but  in  small  works  it 
is  of  considerable  importance.  We  would,  however,  ourselves 
rather  see  the  different  sizes  and  classes  of  work  effected  under 
different  sized  hammers — with  hammers  perfectly  proportioned  to 
each  description  of  work.  Excepting  in  very  large  establishments, 
however,  where  there  are  a  considerable  number  of  hammers  em- 
ployed, this  cannot  always  be  accomplished.  The  consequence  is 
that  the  hammer  is  used  more  as  a  squeezer,  Frequently  crushing 
the  iron  at  the  heart  instead  of  drawing  it  in  a  sound  manner  under 
a  hammer  proportioned  to  its  size.  Where  the  works,  therefore, 
are  not  extensive,  or  where  the  number  of  hammers  is  limited,  the 
facility  of  regulating  the  stroke  by  the  steam-hammer  is  an  im- 
portant advantage  in  many  descriptions  of  work.  Another  advan- 
tage is,  that  the  hammer  is  always  working  parallel  with  the  "piece" 
under  operation,  which  is  not  the  case. with  the  old-fashioned  helves, 
in  using  which  the  hammerman  has  to  resort  to  many  ingenious 
plans,  such  as  employing  thickness  pieces,  for  overcoming  this 
difficulty. 

The  hammerman  is  saved  a  great  deal  of  trouble  in  regulating 
his  tools,  by  using  the  steam-hammer.  With  the  old-fashioned 
helve,  almost  every  different  heat  requires  an  alteration  of  the  tools 
employed ;  with  the  steam-hammer  there  is  no  necessity  for  any 
such  change.  This  of  itself  is  a  considerable  advantage.  With 
the  Nasmyth  hammer  he  is  also  enabled  to  work  on  each  side  of 
the  hammer,  as  it  can  be  placed  in  such  a  position  as  to  be  accessible 
on  both  sides. 

There  are,  however,  a  few  defects  even  in  this  beautiful  tool ;  and 
the  first  which  presents  itself  to  our  mind  is,  that  the  same  quantity 
of  steam  is  consumed  in  striking  a  blow  of  one  foot  upon  a  piece, 
say  of  three  feet  diameter,  as  is  required  for  a  blow  of  three  feet 
upon  a  piece  one  foot  diameter ;  for,  the  stroke  of  the  hammer  being 
fixed,  the  cylinder  takes  the  same  quantity  of  steam  in  lifting  the 
8 


114  THE   PRACTICAL   METAL-WORKER^  ASSISTANT. 

harnmer  the  last  foot  as  it  does  in  lifting  it  the  whole  of  the  stroke. 
This  might,  no  doubt,  be  remedied  by  some  arrangement  for  raising 
or  lowering  the  cylinder  according  to  the  height  of  the  "  piece" 
upon  which  the  blow  is  to  be  struck,  which  would  be  somewhat 
similar  to  the  arrangement  in  operating  with  the  belly-helve,  already 
described.  Another  defect,  but  one  which  attempts  have  been 
made  to  remedy  in  some  modifications  of  the  steam-hammer,  arises 
from  the  difficulty  of  swinging  the  "  piece"  to  be  operated  upon, 
from  the  furnace  to  the  hammer,  one  of  the  legs  of  the  hammer 
being  sometimes  in  the  way.  This  difficulty  might  be  overcome 
by  allowing  the  hammer  to  stand  upon  one  strong  leg,  which  would 
in  many  cases  be  a  considerable  improvement.  We  have,  also,  a 
great  objection  to  the  amount  of  gearing  connected  with  the  work- 
ing of  the  valves.  They  are  certainly  very  beautiful,  and  of  most 
ingenious  construction :  but  in  all  forging  tools  it  is  desirable  that 
the  greatest  simplicity,  combined  with  the  greatest  strength,  should 
always  be  the  first  consideration.  Arrangements  have  lately  been 
made,  we  believe,  for  dispensing  with  these  valves,  and  introducing 
in  their  place  a  simple  balance-valve  capable  of  being  worked  with 
great  ease,  and  not  so  liable  to  get  out  of  order. 

'We  have  thus  given  some  slight  description  of  the  different 
hammers  employed  in  a  forge.  It  has  not  been  our  intention  to 
enter  into  very  minute  details  upon  this  subject,  nor  to  advance  any 
very  decided  opinion  as  to  the  relative  merits  of  the  different  imple- 
ments ;  for  we  are  aware  that  opinions  greatly  differ  upon  these 
points.  The  improvements  that  have  taken  place  in  this  descrip- 
tion of  tools  during  the  last  fifteen  years  have  been  very  great ; 
but  we  are  prepared  to  witness  still  greater  developments  of  me- 
chanical application  in  connection  with  this  branch  of  the  art. 

MATERIALS. — We  now  propose  to  give  a  short  description  of  the 
materials  consumed  in  the  forge,  the  chief  of  which  are  the  coals 
and  the  iron.  It  is  of  considerable  importance  that  care  should  be 
used  in  the  selection  of  the  fuel  for  the  manufacture  of  forgings,  as 
great  difference  exists  in  this  important  mineral,  some  being  very 
much  more  suitable  for  the  manufacture  than  others.  The  best 
bituminous  for  the  purpose  is  a  strong,  dense,  durable  coal,  possess- 
ing a  good  body,  and  having  a  dull,  dirty  appearance.  Coal  of 
this  kind  with  a  bright  clean  look,  easily  broken,  as  a  general 
rule  is  not  suitable.  Of  course  it  is  desirable  that  the  coal  should 
be  as  free  from  sulphur  as  possible,  and  that  it  should  not  contain 
any  large  proportion  of  those  foreign  matters  which,  having  an 
affinity  for  iron,  fuse  on  the  bars  in  the  shape  of  clinkers. 

We  now  come  to  the  consideration  of  the  best  description  of  iron 
for  this  manufacture.  Scrap-iron  is  that  most  generally  used ;  but, 
far  from  agreeing  with  the  generally  received  opinion  that  it  is  the 
best,  we  think  that  it  is  the  very  worst  description  of  iron  for  the 
purpose ;  and  for  more  reasons  than  one.  Engineers  usually  re- 
quire, in  their  contracts  with  the  forge-master,  that  their  forging* 
shall  be  made  from  the  best  scrap-iron ;  and  it  is,  of  course,  the 


ON   WROUGHT-IRON   IN   LARGE   MASSES.  115 

duty  of  the  forge-master  to  comply  with  the  terms  of  his  instruc- 
tions and  contract.  Let  us  first  endeavor  to  see  how  this  almost 
universal  belief  in  the  superiority  of  scrap-iron  has  arisen.  At 
the  time  when  small  forgings  were  first  attempted  to  be  made  as  an 
article  of  commerce,  the  manufacture  of  iron  was  in  such  an  im- 
perfect state,  and  the  quality  so  indifferent,  that  large  quantities  of 
the  best  iron  had  to  be  imported  from  Sweden  and  Russia,  and  for  a 
long  time  the  scrap-iron  was  of  a  quality  that  could  not  be  approached 
by  our  own  iron  of  that  period.  Since  that  time,  the  use  of  Russian 
and  Swedish  iron  has  been  almost  entirely  discontinued,  except  for 
the  manufacture  of  steel ;  the  greater  part  of  the  scrap-iron  now  pro- 
duced, therefore,  is  of  a  very  different  quality  to  that  formerly  known 
as  best  scrap-iron.  This  material  was  deservedly  considered  the  most 
proper  material  for  the  manufacture  of  forgings  that  could  then  be 
procured ;  but  it  must  be  borne  in  mind  that,  at  the  date  we  speak  of, 
the  forgings  were  so  limited  in  size  that  the  practical  evils  result- , 
ing  from  the  use  of  scrap-iron,  which  we  are  about  to  explain,  were 
not  so  perceptible. 

In  the  ordinary  manufacture  of  bar-iron  it  is  the  practice,  in  most 
works,  in  order  to  obtain  it  of  the  toughest  and  best  description,  to 
work  and  re-work  it  several  times  over.  The  number  of  workings 
the  iron  undergoes  is  marked  by  the  number  of  "  best"  stamps  that 
it  bears,  as  "  best,  best  best,"  "  treble  best,"  etc.,  each  "  best"  indicat- 
ing a  better  quality,  an  extra  working,  and  with  a  correspondingly 
higher  price.  But  this  progressive  improvement  has  its  limits,  as 
will  be  perceived,  from  a  series  of  experiments  which  were  insti- 
tuted by  the  writer  with  the  object  of  testing  the  correctness  and 
limits  of  this  improvement. 

Taking  a  quantity  of  ordinary  fibrous  puddled-iron,  and  reserv- 
ing samples  marked  No.  1,  we  piled  a  portion  five  feet  high,  heated 
and  rolled  the  remainder  into  two  bars  marked  No.  2 ;  again  re- 
serving two  samples  from  the  centre  of  these  bars,  the  remainder 
were  piled  as  before,  and  so  continued  until  a  portion  of  the  iron 
had  undergone  twelve  workings.  The  following  table  shows  tho 
tensible  strain  which  each  number  bore : 

No.  1  puddled  bar  43,904  Ibs. 

"    2  re-heated  .  .  52,864  " 

"    3         '  59,585  " 

"    4        "  59,585  " 

"5        "  57,344  « 

6  "  61,824  " 

7  "  59,585  " 

8  "  57,344  " 

9  "  57,344  " 

10  "      54,104  " 

11  "      51,968  " 

12  "      43,904  " 

It  will  thus  be  seen  that  the  quality  of  the  iron  regularly  in- 


116  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

creased  up  to  No.  6  (the  slight  difference  of  No.  5  may  perhaps  be 
attributed  to  the  sample  being  slightly  defective) ;  and  that  from 
No.  6  the  descent  was  in  a  similar  ratio  to  the  previous  increase. 
From  these  experiments  it  appears  that  scrap-iron,  or  any  other 
iron,  highly  refined,  is  the  very  worst  material  for  the  construction 
of  large  forgings  which  can  be  used ;  and  that  if  we  take,  in  the 
first  instance,  a  strong  fibrous  fresh-puddled  iron,  the  ordinary 
workings  required  in  the  process  of  forging  will  be  sufficient  to 
improve  it  to  the  average  maximum  of  strength  required  ;  whereas 
highly  refined  iron,  such  as  Lowmoor  or  Bowling,  although  the 
very  best  description  for  many  purposes,  has  already  reached  the 
highest  point  in  its  strength;  from  which  it  is  more  likely  to  be 
deteriorated  by  additional  workings. 

It  may  then  be  asked — how  can  we  hope,  with  any  degree  of 
success,  to  manufacture  large  forgings,  which  require  to  be  worked 
over  perhaps  a  score  of  times,  each  working  beyond  a  given  num- 
ber tending  to  vitiate  the  iron  ?  We  can  conceive  that  this  deteri- 
oration does  not  penetrate  the  iron  to  any  great  depth ;  that  few 
forgings  are  heated  more  than  six  times  in  one  place  before  fresh 
iron  is  added ;  and  that  the  various  layers  thus  successively  added 
to  the  mass  protect  the  under  portion  from  the  deteriorating  in- 
fluences of  the  successive  'heatings.  It  is  also  to  be  observed  that 
any  crystallization  which  might  take  place,  commences  from  the 
outside  of  the  mass;  and  as  this  is  the  portion  which  is  most 
immediately  acted  upon  by  the  blows  of  the  hammer,  the  fibre  is 
elongated  in  a  greater  degree,  and  thus  restored  to  its  original 
quality.  As  a  proof  of  this,  we  may  instance  the  manufacture  of 
the  monster  gun,  which  was  built  up  in  seven  distinct  layers,  the 
forging  of  which  took'  seven  weeks. 

At  the  meeting  of  the  British  Association  at  Glasgow,  in  Sep- 
tember, J855,  a  question  was  raised  in  the  mechanical  section  as 
to  the  causes  of  the  deterioration  of  the  metal  of  which  the  artil- 
lery of  the  present  day  was  constructed.  On  this  question  a  long 
and  interesting  discussion  ensued,  both  in  reference  to  the  compara- 
tive weakness  of  cast-iron  as  now  produced,  and  the  adaptation  of 
forged  and  malleable  iron  as  being  stronger  and  better  adapted  for 
this  purpose.  The  accounts  received  from  the  Baltic  and  Black 
Seas  of  the  bursting  of  guns  and  mortars  of  recent  construction, 
indicated  that  something  was  wrong.  These  failures  gave  rise  to 
conjectures  on  the  part  of  the  Government  as  well  as  of  the  public  ; 
and,  in  order  to  trace  the  cause  of  this  apparent  weakness  to  its 
source,  an  inquiry  was  institued  by  the  authorities  at  Woolwich ; 
and  subsequently  the  Association  appointed  a  Committee  to  co- 
operate with  the  Government  in  the  investigation  of  this  very  im- 
portant question.  In  order  that  no  time  might  be  lost,  the  secre- 
tary of  the  section  was  directed  to  issue  circulars  to  engineers,  iron- 
masters, and  manufacturers,  requesting  that  they  would  forward  to 
the  members  of  the  Committee  such  opinions  and  observations  as 


ON   WROUGHT-IRON   IN   LARGE   MASSES.  117 

they  deemed  advisable,  in  regard  to  the  material  itself,  and  to  its 
treatment  preparatory  to  the  manufacture  of  ordnance." 

It  is  to  be  regretted  that  these  circulars  were  not  made  more 
general,  and  that  more  of  them  were  not  addressed  to  practical 
forge-masters ;  for  we  observe,  among  the  replies  elicited,  the 
name  of  one  man  only  practically  and  intimately  connected  with 
the  manufacture  of  large  masses  of  wrought-iron  ;  and  his  reply 
is  the  only  one  indicating  any  hope  of  success  in  the  application  of 
wrought-iron  for  ordnance  purposes.  All  the  other  writers  who  no- 
ticed wrought-iron  at  all  (for  many  passed  it  by  without  the  slightest 
attention)  most  unequivocally  condemned  it,  and  came  to  the  con- 
clusion, that  "the  tendency  to  crystallization  which  the  long-con- 
tinued heating  produces  is  such,  that  powerful  ordnance  cannot  be 
manufactured  advantageously  from  malleable  iron." 

It  was,  perhaps,  fortunate  that  the  manufacturers  of  the  monster 
gun  were  not  aware  of  the  adverse  opinions  thus  pronounced 
against  wrought-iron  for  ordnance;  otherwise,  they  might  have 
been  discouraged  in  their  attempt,  aud  what  must  now  be  consid- 
ered the  successful  manufacture  of  large  wrought-iron  ordnance 
might  have  been  postponed.  The  following  table  of  the  tensile 
strength  of  the  iron  before  it  entered  into  the  composition  of  the 
gun ;  of  the  iron  cut  from  it,  and  as  it  now  is  in  the  gun,  both 
transverse  and  longitudinal  to  the  grain ;  and  of  the  borings  from 
the  gun,  worked  over  again  in  different  ways, — tend  to  show  that, 
so  far  from  deterioration  or  crystallization  having  taken  place,  the 
metal  was  improved  by  its  long-continued  heating  and  working : 

Breaking 
Experiment  Description  of  Iron.  strain  in  Ibs. 

per  sq.  iu. 

No.    1.  Original  iron  of  which  the  gun  was  made     48-384 
No.    2.  Ditto  ditto  50-624 

No.    3.  Cut  across  the  grain  from  muzzle  of  gun     41-644 
No.    4.  Ditto  ditto  43-904 

No.    5.  Ditto  ditto  50-624 

No.    6.  Cut  with  the  grain  from  muzzle  of  gun        48-384 
No.    7.  Ditto  ditto  50-624 

No.    8.  Ditto  ditto  62-864 

No.    9.  Borings  from  gun  worked  over  with  coal       60-584 
No.  10.  Ditto  ditto  62-824 

No.  11.  Borings  from  gun  worked  over  with  charcl.  76-584 
No.  12.  Swedish  iron  as  imported,  ^  sq.         ',     ,       60-564 

From  the  above  experiments  it  will  be  seen  that  the  original 
iron  put  into  the  gun  was  of  no  extraordinary  strength,  which  is 
accounted  for  by  the  fact  that  it  was  designedly  selected,  in  conse- 
quence of  the  experiments  already  quoted,  from  what  is  commonly 
known  as  "  No.  2  iron,"  or  iron  once  worked  over  from  the  pud- 
dling- process,  though  of  considerable  strength  and  body,  and  com- 
mercially called  "  common  iron."  This  iron,  after  seven  weeks 
heating  and  shaping  into  a  gun,  was,  as  we  have  already  stated,  so 
far  from  being  deteriorated  by  this  "  long  exposure  to  great  heat/' 
as  to  be  actually  improved  in  quality ;  for  we  find  that  the  aver- 
age of  the  trials  gives  an  increase  oi  tensile  strength  from  49'504 


118  THE   PEACTICAL   METAL-WORKER'S  ASSISTANT. 

Ibs.  per  square  inch  to  50624  Ibs.,  both  trials  being  longitudinal 
with  the  fibre  or  grain  of  the  iron. 

The  strength  of  the  iron  across  the  grain  can  hardly  be  regarded 
as  of  much  importance,  although  it  exhibits  a  remarkable  amount 
of  cohesion,  for  it  was  laid  in  the  direction  of  the  strain,  and  there- 
fore the  cut  transverse  to  the  grain  might  have  been  expected  to 
possess  less  cohesion  in  that  direction  than  if  the  grain  had  been 
placed  in  its  position  accidentally. 

If  we  follow  this  question  further,  and  examine  the  result  of 
working  over  again  the  borings  from  this  forging,  we  find  that  the 
tensile  strength  is  increased  from  49 '504  Ibs.  per  square  inch  to 
61-704  Ibs.  when  treated  with  coke,  and  76*584  Ibs.  when  worked 
with  charcoal ;  and  we  think  with  results  such  as  these — without 
parallel  in  any  English  make  of  iron,  even  under  the  most  favor- 
able circumstances — we  may  be  allowed  to  assent  that  the  myth 
commonly  called  "  crystallization  from  long  exposure  to  great 
heats,"  does  not  apply  to  the  fabrication  of  this  the  largest  forging 
ever  made.  We  have  given  these  details  to  illustrate  and  enforce 
the  preference  given  to  puddled-iron  over  scrap-iron ;  but  there  is 
another  very  important  reason  why  scrap-iron  should  not  be  used 
for  the  manufacture  of  forgings — scrap-iron  is  composed  of  many 
various  qualities  of  iron,  and  all  of  them  have  their  own  special 
welding  points.  When  worked  together,  one  portion  that  is  less 
refined  is  too  much  heated,  and^  consequently  deteriorated,  before 
the  more  highly  refined  portions  are  at  a  welding  heat ;  and  we 
are  thus  placed  in  the  awkward  dilemma  of  either  burning  the 
one,  or  of  being  unable  to  weld  the  other.  It  may  be  said  that 
this  objection  is  a  mere  theoretical  one,  and  that,  practically,  no 
such  difficulty  exists.  This,  however,  is  not  the  case,  for  the  dif- 
ference of  temperature  at  which  puddled-iron  and  a  highly-refined 
iron  weld  is  very  considerable ;  although,  from  the  difficulty  of 
finding  a  really  good  pyrometer  for  these  extreme  heats,  we  are 
unable  to  give  exact  data  in  degrees.  If  any  proof  were  required 
of  this,  which  is  a  matter  of  every-day  economy,  it  is  only  neces- 
sary to  inquire  into  the  heating  of  iron  for  our  rolling-mills.  It 
is  a  well-established  fact,  that,  in  the  mixing  of  different  descrip- 
tions of  iron  in  the  piles  for  that  purpose,  the  hardest  and  most 
refined  iron  is  always  placed  outside,  and  the  puddled  or  common 
iron  inside.  Were  a  contrary  practice  pursued,  and  puddled-iron 
of  ordinary  quality  placed  at  the  outside,  and  the  highly-refined 
or  scrap  placed  in  the  centre  of  the  pile,  the  outer  or  puddled-iron 
would  be  wasted  and  destroyed  before  the  inner  portion  was  suffi- 
ciently hot  to  weld. 

We  may  also  call  attention  to  the  various  qualities  found  among 
scrap-iron,  some  being  what  are  termed  "hot-short,"  and  others 
"  cold-short."  We  have  before  quoted  a  writer  on  the  subject  of 
the  manufacture  of  wrought-iron  for  ordnance,  who  has  stated  that 
the  limit  has  been  reached  beyond  which  forgings  cannot  be  made  ; 
assigning  reasons  for  those  limits  according  to  his  own  ideas  and 


ON  WROUGHT-IRON   IN   LARGE   MASSES.  119 

experience,  the  principal  one  being  the  assumed  difficulty  of  heat- 
ing such  large  masses.  Now,  if  we  take  strong  puddled-iron  in 
place  of  the  "  scrap,"  which  has  hitherto  been  the  material  generally 
used,  we  effect,  as  we  have  shown,  a  saving  of  say  about  20  per 
cent,  in  the  heat  required  to  unite  soundly  the  various  slabs  or  por- 
tions of  which  the  "  piece"  is  composed ;  in  other  words,  by  this 
simple  substitution  of  the  material  used,  we  increase,  to  the  extent 
of  about  20  per  cent.,  the  suppositions  limits  of  the  writer  from 
whom  we  have  quoted,  but  the  accuracy  of  whose  conclusions  we 
challenge. 

MANUFACTURE. — But  scrap-iron,  though,  as  we  have  endeavored 
to  show,  the  worst  for  our  purpose,  is  the  material  from  which 
forgings  are  generally  made ;  and  we  must  say  a  word  or  two  as  to 
its  preparation.  It  is  necessary,  in  the  first  place,  that  the  small 
pieces  of  scrap-iron  should  undergo  a  cleaning  process.  For  this 
purpose,  they  are  generally  placed  in  a  large  drum  or  vessel,  which 
is  caused  to  rotate  at  a  considerable  velocity  by  machinery ;  and 
they  are  thus,  to  a  certain  extent,  freed  from  oxide  and  various 
other  superficial  impurities,  that  would  otherwise  injure  the  material 
for  forging  purposes.  In  some  works,  where  large  quantities  of 
scrap-iron  are  consumed  for  this  and  other  purposes,  the  scrap  is 
usually  carefully  selected ;  and  none  but  blue  and  clean  iron,  pure 
as  when  it  came  from  the  manufacturer's  hands,  is  permitted  to  be 
used  for  forgings,  the  rusty  and  dirty  iron  being  set  aside  for  con- 
version to  more  common  purposes,  such  as  the  manufacture  of 
" bar-iron,"  "grate-bars,"  etc. 

The  scrap-iron,  having  been  thus  cleaned  or  selected,  is  divided 
into  lumps  or  masses  of  various  descriptions,  by  being  piled  in 
quantities  generally  varying  from  100  to  200  Ibs.  in  weight  on  a 
slate  or  tile.  These  piles  are  charged  into  a  reverberating  furnace, 
commonly  called  a  "heating"  or  "balling"  furnace.  After  re- 
maining about  one  hour  and  a  quarter,  they  are  sufficiently  heated 
to  be  forged  out  into  slabs  or  "  blooms."  The  piling  of  the  iron  is 
an  operation  requiring  considerable  skill  and  experience,  for  if  the 
pile  is  not  solidly  put  together,  it  will  fall  down  in  the  furnace,  and 
perhaps  become  attached  to  others.  About  ten  to  eighteen  of  these 
piles,  according  to  their  size,  constitute  a  charge  or  "heat;"  and  a 
good  workman  will  turn  out  six  charges  per  day,  or  about  3  tons 
10  cwt.  to  4  tons.  Larger  descriptions  of  slabs  are  used  for  many 
purposes;  and  several  of  those  described  are  again  piled  together, 
subjected  to  the  heating  process,  and  hammered  to  the  required 
shape.  In  some  forges  the  same  workman  "  shingles"  or  hammers 
his  iron  from  the  scrap-pile,  and  heats  it  in  the  same  furnace  in 
which  he  heats  his  forgings;  but  this  is  by  no  means  a  judicious 
arrangement.  It  is  much  better,  especially  with  large  work,  that 
there  should  be  a  division  of  these  operations,  and  that  a  certain 
number  of  men,  of  inferior  skill,  and  consequently  of  less  value, 
should  heat  and  "  shingle"  the  iron  for  the  first  processes,  and  de- 
liver it  to  the  more  highly -paid  and  skillful  hammerman  in  a  further 


120 


THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 


advanced  and  more  convenient  shape.  There  is  another,  and  by 
no  means  inconsiderable  advantage  to  be  obtained  by  this  arrange- 
ment. A  much  larger  amount  of  work  can  be  accomplished  with 
the  same  number  of  men  and  tools,  than  in  the  case  where  the  two 
classes  of  work  are  completed  by  one  workman.  These  slabs  vary 
in  shape  and  size,  according  to  the  nature  of  the  work  for  which 
they  are  intended ;  and  are  delivered  to  the  hammerman  accord- 
ingly. 

In  large  forgings,  each  particular  piece  requires  different  treat- 
ment, according  to  the  shape  and  use  for  which  it  is  intended.  On 
this  depends  tthe  question  of  the  best  manner  of  making  it.  For 
instance,  a  screw-shaft,  which  is  subject  to  torsion,  requires  that 
the  iron  should  be  put  together  in  a  manner  very  different  from 
the  mode  in  which  a  crank  or  cross-head  is  prepared.  We  will 
take  the  case  of  shafts.  The  most  ancient  method  of  forging  them 
was  to  take  a  certain  number  of  slabs  or  plates  of  iron,  made  into 
a  pile  thus,  (Fig.  75),  and  after  heating  them,  to  hammer  them  into 


Fig.  75.     End  View, 


Fig.  75.     Front  View. 


the  round  shape  required.  As  it  soon  became  necessary  to  make 
larger  shafts,  however,  and  as  this  pile  could  not  conveniently  be 
increased,  an  improvement  was  introduced,  which  consisted  in 
taking  a  pile  of  slabs  as  before,  and  drawing  a  portion  only  of  the 
mass  into  the  shape  required  (see  Fig.  76),  leaving  a  lump  on  the 
end  on  which  to  place  more  slabs  as  needed ;  then  drawing  a  little 
more  at  A  to  the  required  shape,  adding  more  and  more  slabs  as 
occasion  required.  This  method  is  still  practised  at  many  works, 
and  with  considerable  success ;  but  it  requires  the  utmost  care  and 
circumspection,  both  in  regard  to  workmanship  and  materials. 
This  is  the  method  by  which  shafts  are  generally  made  in  the  north 
of  England  and  Scotland,  and  in  America. 

Fig.   76.     Front  View. 


Another  plan  is  to  lay  up  a  faggot  of  square  bars  sufficient  to 
make  the  required  shaft  (Fig.  77).  This  is  a  considerable  improve- 
ment upon  the  slab-plan,  there  being  much  less  risk  of  false  weld- 


ON   WROUGHT-IRON   IN   LARGE   MASSES.  121 

ings  and  careless  workmanship ;  and  for  this  reason,  when  slabs 
are  used,  if  the  heat  has  not  been  sufficient  to  give  a  perfect  weld 
to  the  iron,  or  if  any  oxide  or  dirt  should  intrude,  the  flaw  or  de- 
fect would  run  more  across  the  shaft  than  in  the  faggot,  where 
indeed  any  flaw  from  such  causes  would  run  longitudinally  with 
the  shaft,  and  consequently  would  not  interfere  in  any  thing  like 
the  same  degree  with  its  strength.  But  this  method  also  requires 
great  care  and  attention ;  for  if  the  faggot  of  square  bars  be  made 
too  large  at  one  heat,  the  interior  of  the  mass  cannot  be  sufficiently 

Fig.  77.     Front  view. 


heated  to  allow  of  the  iron  being  welded  at  the  centre.     I  have 

Fig.  77.    End  view.  Fig.  78.    End  view. 


often  seen  a  broken  steamboat  shaft  which  has  never  been  united 

Fig.  78.     Front  view. 


at  all  at  the  heart,  the  bars  from  which  it  was  made  being  in  the 
same  shape  and  state  as  when  they  were  placed  in  the  faggot.  To 
avoid  this  great  evil  it  is  necessary  to  be  especially  careful  not  to 
pack  faggots  too  large  at  once,  but  to  make,  in  the  first  instance,  a 
moderate-sized  one,  which,  after  being  worked  perfectly  sound,  has 
another  layer  of  bars  packed  round  it,  and  so  on  with  further 
layers,  until  the  necessary  size  is  attained  with  perfect  soundness. 
Thus  Fig.  78,  A  being  the  original  faggot  after  it  has  been  made 
sound  and  solid,  has  the  bars,  as  shown,  packed  round  it ;  it  is  then 
again  heated  and  hammered  into  the  required  shape. 

The  tliird  method  of  manufacturing  large  shafts  is  commenced 


122  THE   PRACTICAL    METAL-WORKEli's   ASSISTANT. 

by  making  a  round  core  or  heart,  B;  and  taking  bars  of  a  V  form 
to  pack  round  it  (Fig.  79).  This  is  a  method  of  forging  railway 
Fig.  79.  Knd  view.  a^es  which  is  frequently  adopted.  It  was  also 
the  method  adopted,  with  some  variations,  in 
forging  the  monster  gun  at  the  Mersey  Iron 
Works.  In  a  previous  page  we  have  given  the 
tensile  strength  of  the  iron  before  it  was  forged 
into  the  gun,  and  its  condition  after  undergoing 
that  process ;  and  it  may  be  satisfactory  if  we 
give  some  details  of  the  manner  in  which  this 
large  forging  was  worked.  * 

We  have  already  stated  that  it  was  built  up  in  seven  distinct 

•        Fig.  79.     Front  view. 


layers  or  slabs,  and  that  the  forging  occupied  seven  weeks.  Nor 
will  this  time  seem  unreasonable  when  its  dimensions  and  weight 
are  remembered.  The  chief  points  to  be  considered  by  the  de- 
signer of  the  gun  were,  to  obtain  sound  weldings ;  to  place  the 
iron,  with  its  fibres,  in  the  proper  direction  for  resisting  the  most 
severe  strains  to  which  it  could  be  exposed  ;  and  to  take  care  that, 
while  working  one  part  of  the  forging,  other  portions  were  not 
wasted  under  the  action  of  the  furnace  by  burning  or  crystalliza- 
tion. The  first  operation  was  to  prepare  a  core  of  suitable  dimen- 
sions, and  nearly  the  whole  length  of  the  gun.  This  was  done  by 
taking  a  number  of  rolled  bars,  about  six  feet  in  length,  welding 
them  together,  and  drawing  them  out  until  the  proper  length  was 
obtained.  A  series  of  V  -shaped  bars  were  now  packed  round  the 
core,  the  whole  mass  heated  in  a  reverberatory  furnace,  and  forged 
under  the  largest  belly-helve  hammer.  Another  series  of  bars  were 
now  packed  on,  and  the  mass  was  heated  again,  and  worked  per- 
fectly sound.  Another  longitudinal  series  of  bars  were  still  re- 
quired over  the  whole  length  of  the  forging,  which  were  added  ; 
and  the  mass  now  presented  a  forging  about  fifteen  feet  in  length 
and  thirty-two  inches  in  diameter,  but  requiring  to  be  augmented 
to  forty-four  inches  at  the  breach,  tapering  down  to  twenty-seven 
inches  at  the  muzzle.  This  was  accomplished  by  two  layers  of 
iron,  placed  in  such  a  manner  as  to  resemble  hoops,  laid  at  right 
angles  to  the  axis  of  the  mass;  and,  after  two  more  heatings  and 
careful  welding,  the  forging  of  the  gun  was  completed.  After 
each  important  addition,  a  "  securing"  heat  was  given  to  prevent 
flaws.  It  would  be  foreign  to  our  purpose  here  to  deal  with  this 
implement  otherwise  than  as  a  mass  of  forged  iron.  Its  di- 


ON   WROUGHT   IRON   IN   LARGE   MASSES.  123 

mansions,  as  given  bj  Captain  Vandaleur,  in  his  report,  are  as 

follow: 

Ft.  IDS. 

Length 15  10 

Diameter  at  base 3       7| 

Diameter  at  muzzle 2       3£ 

Diameter  at  trunnions 3  3£ 

Length  of  bore 13  4 

Diameter  of  bore 0  13'05 

Its  present  weight  is  21  tons  17  cwt.  1  qr.  14  Ibs.  The  original 
weight,  before  boring,  was  25  tons.  The  furnace  employed  was  a 
reverberatory  one;  and  the  hammer,  as  we  have  seen,  was  the 
great  belly -helve  tilt-hammer,  weighing  10  tons.  As  already  inti- 
mated, the  iron  bored  out  of  the  gun  was  tough,  sound,  and  per- 
fectly homogeneous,  some  of  the  borings  being  curled  like  a  watch- 
spring  seven  times  round  ;  and,  when  worked  up  again,  it  bore  the 
test  applied  to  prove  its  strength,  as  reported  at  page  117 ;  and 
Messrs.  Horsfall  have  the  satisfaction  of  having  produced  a  forging 
which  the  scientific  world  had  hitherto  deemed  impracticable. 

Shafts  have  sometimes  been  made  after  another  method,  which 
we  consider  very  injudicious.  Many  specimens  of  this  mode  of 
manufacture  have  come  under  the  notice  of  the  writer  in  the  shape 
of  broken  shafts,  where  the  unsoundness,  arising  from  the  method 
of  working  adopted,  has  been  so  great  as  to  make  it  a  matter  of 
surprise  that  the  shaft  had  done  any  duty  at  all. 

The  method  in  question  was  to  forge  four  large  square  bars, 
proportioned,  of  course,  to  the  size  of  the  shaft  required ;  packing 
them  together  (Fig.  80).  This  faggot  was  of  such  immense  size, 

Pig.  80.     Front  view. 


that  the  furnace  and  hammer  employed  were  altogether  insufficient 

tO   produce    SOUnd   WOrk.      As   a       Fig.  80.   End  view.  Fig.  81. 

necessary  consequence,  when  the 
shafts  so  made  were  broken,  the 
fracture  had  an  appearance  sim- 
ilar to  Fig.  81,  being  only  welded 
on  the  circumference ;  while  the 
four  fissures  at  the  centre  were  sufficient,  in  many  cases,  to  receive 
a  man's  hand,  while  a  rod  of  iron  could  be  inserted  from  one  end 
to  the  other. 

CRYSTALLIZATION.— A  great  deal  has  been  said  and  written  with 
reference  to  a  supposed  deterioration,  or,  as  it  has  been  called, 
'•  crystallization"  of  iron,  when  rolled  in  large  masses,  from  long- 
continued  and  frequent  heatings.  It  has  also  been  asserted  that  the 


124  TIIE   PRACTICAL   METAL  WORKER'S   ASSISTANT. 

iron,  while  lying  in  the  furnace,  is  continually  attracting  carbon 
from  the  grate,  until,  in  course  of  time,  it  becomes  carburetted, — 
that  is,  reconverted  into  pig-iron.  When  this  theory  was  first  pro- 
pounded, the  writer  determined  to  test  its  accuracy ;  and  that  in 
the  presence  of  the  gentlemen  by  whom  it  had  been  promulgated. 
A  small  knob,  or  corner,  was  accordingly  detached  from  a  large 
forging  which  had  been  over-heated  or  burnt.  It  broke  off  with 
a  large  flaky  appearance  very  similar  to  some  descriptions  of  lead 
ore.  This  was  pronounced  to  be  very  similar  in  its  nature  to  cast- 
iron,  and  in  the  so-called  crystallized  state.  Proceeding  to  the 
smiths'  department,  the  iron  was  heated  in  the  fire,  and  drawn 
down  to  about  three  times  its  original  length.  It  worked  well 
under  the  hammer ;  and  when  broken  again  in  the  usual  way,  was 
as  beautifully  fibrous  as  the  iron  from  which  it  was  originally  made. 
This  experiment  led  to  the  conclusion  that  the  iron  acted  upon  was 
very  different  in  its  nature  from  cast-iron,  and  certainly  failed  in 
sustaining  the  crystallization  theory. 

It  may  be  well,  however,  in  the  first  place,  to  consider  what  is 
the  meaning  attached  to  this  term  "  crystallization."  It  has  been 
generally  used  to  signify  that  the  structure  or  composition  of  the 
iron  has  entirely  changed  its  character  and  assumed  a  new  form. 
Mr.  Mallet,  in  page  110  of  his  work  before  quoted,  thus  describes 
this  change : 

"  With  the  same  iron  and  the  same  volume  of  forging,  however, 
the  size  of  the  crystals  appears  to  be  large  and  more  developed  in 
proportion  to  the  time  that  the  mass  is  maintained  hot  and  in  pro- 
cess of  forging.  This  time  is  necessarily  greater  as  the  mass  is  so ; 
and  as  the  operation  of  reducing  it  to  the  required  form  is  more 
complex  or  laborious.  In  fact,  as  in  cast-iron,  we  saw  that  the 
crystals  were  larger  the  longer  the  mass  required  to  cool ;  so  in 
wrought-iron,  they  are  larger  the  longer  the  mass  is  kept  hot :  and 
thus  it  happens  that  in  very  large  and  massive  forgings,  requiring 
often  to  be  maintained  perhaps  for  weeks,  at  temperatures  varying 
from  welding-heat  down  to  dull  redness,  crystals  are  developed 
within  the  mass  of  a  size  tending  materially  to  diminish,  in  some 
places,  the  average  cohesion  of  the  iron,  where  their  planes  of 
cleavage  produce  partial  planes  of  weakness.  The  size  of  these 
crystals  is  occasionally  surprising  ;  the  broadest  and  flattest  planes 
of  cleavage  frequently  running  in  the  direction  in  which  surfaces 
of  the  integrant  slabs,  or  portions  of  iron  of  which  the  mass  has 
been  formed,  have  been  welded  together.  The  author  has  observed 
crystals  to  deposit  flat  planes  as  large  as  the  surface  of  a  half-crown 
piece  in  forgings  under  seven  tons  weight." 

We  have  little  doubt  that  in  many  instances  this  statement  is 
perfectly  correct ;  we,  however,  at  the  same  time  declare  our  belief 
that  cases  are  referred  to  where  the  greatest  carelessness  and  inat- 
tention on  the  part  of  the  workmen  have  been  exhibited.  We  think, 
moreover,  that  some  experiments  which  have  taken  place,  and  others 
which  are  still  making,  under  the  direction  of  Mr.  Mallet,  will 


ON  WROUGHT   IRON   IN   LARGE   MASSES.  125 

induce  him  to  alter  his  opinion  on  this  point.  To  one  of  these  we 
may  here  allude  in  support  of  this  view :  a  sample  bar  has  been 
planed  out  of  the  body  of  a  large  wrought-iron  mortar  piece  made 
for  him,  and  the  sample  shows  a  highly  fibrous  development,  very 
different  in  appearance  from  the  specimens  described  by  Mr.  Mallet 
in  the  above  extract — a  description,  be  it  observed,  which  may  be 
at  any  time  observed  in  a  forge  on  examining  a  piece  of  burnt  iron 
or  in  an  exposed  corner  which  has  been  subjected  to  very  great  but 
not  necessarily  continued  heat. 

It  seems  to  us  that  all  wrought-iron  is,  more  or  less,  crystalline 
in  its  structure;  and  that  the  difference  between  what  we  call 
fibrous  and  crystallized  iron  only  consists  in  the  degree  of  fineness 
in  the  crystals,  and  perhaps  in  the  manner  in  which  they  are  laid 
together ;  the  presence,  also,  of  foreign  matters,  such  as  silicon,  in 
some  form,  may  also  have  its  influence.  Whatever  the  cause  may 
be,  however,  it  is  known  that  a  piece  of  good  fibrous  iron  will  break, 
under  the  smith's  hammer,  with  a  long  silky  appearance ;  if  suddenly 
fractured  by  an  irresistible  blow,  the  same  piece  of  iron  will  break 
crystalline,  but  the  crystals  will  be  very  fine  and  close,  and  of  a 
good  color. 

In  some  experiments  made  at  Woolwich,  in  the  year  1842,  to 
test  the  effect  of  shot  against  wrought-iron  plates,  and  determine 
whether  wrought-iron  was  a  suitable  material  for  ships  of  war,  it 
was  found  that  the  toughest  and  most  fibrous  plate-iron,  when 
struck  by  shot,  was  instantaneously  crystallized ;  while  the  pieces 
struck  out  were  so  hot,  that  the  fragments,  even  after  passing  a 
considerable  distance  through  the  air,  could  not  be  handled  with 
the  naked  hand ;  in  many  cases  the  fracture  had  that  blue  appear- 
ance, which  is  indicative  of  considerable  heat. 

A  68-pounder  wrought-iron  gun  burst  with  the  first  charge  at 
Woolwich,  on  the  12th  of  July,  1855 ;  on  examination,  the  iron 
was  pronounced  to  be  crystallized,  and  its  nature  changed,  by  long 
exposure  to  great  heat.  This  crystalline  appearance  was,  most 
probably,  the  result  of  the  very  sudden  disruption,  as  in  the  ex- 
periments with  'the  iron  plates ;  and,  according  to  our  view  of  the 
case,  is  traceable  to  bad  workmanship.  A  considerable  portion  of 
the  bars  of  which  the  forging  was  composed  had  never  been  welded 
at  all ;  and  no  doubt  the  fracture  commenced  with  these  false  weldings. 
The  crystalline  appearance,  where  the  iron  was  torn  from  the  solid 
mass,  arose,  at  any  rate,  to  a  great  extent,  from  the  sudden  fracture. 
Other  causes,  no  doubt,  assisted ;  among  which  the  selection  of  iron 
too  highly-refined  may  be  included.  From  this  crystalline  ap- 
pearance, the  authorities  of  the  Ordnance  Department  arrived  at 
the  conclusion,  that  large  masses  of  iron,  from  long-continued  heat- 
ing, have  a  tendency  to  crystallize,  and  lose  the  properties  peculiar 
to  wrought-iron.  Acting  on  this  hypothesis,  they  put  a  stop  to 
what  were  called  "Nasmyth's  experiments"  at  Patricroft,  pro- 
nouncing the  manufacture  of  a  wrought-iron  gun  of  large  size  im- 
possible— a  theory  which  the  successful  manufacture  of  a  much 


126  THE  PEACTICAL   METAL-WORKER'S   ASSISTANT. 

larger  piece  lias  since  practically  shown  to  be  incorrect.  As  we 
have  before  shown,  a  bar  of  iron,  planed  transversely  from  a  piece 
cut  off  the  end  of  the  gun,  broke  with  a  fibrous  texture,  and  with 
a  very  slight  tendency  to  crystallization ;  and  that  crystal  by  no 
means  of  a  large  character.  This  sample  had  never  been  treated  or 
.altered  in  the  slightest  degree  since  it  was  cut  off  the  gun,  and  it 
would  be  pronounced  "  excellent  best  iron."  A  portion  of  this  was 
afterwards  rolled  down  to  three-eighths  of  an  inch  round  bar-iron, 
and  it  was  bent  cold  in  all  ways  without  giving  way  in  the  slightest 
degree. 

Having  thus  endeavored  to  explain  the  meaning  of  the  term 
"  crystallization,"  let  us  now  endeavor  to  trace  the  causes  which 
produce  this  result. 

The  change  in  the  structure  of  the  mass  of  iron,  when  it  occurs 
during  the  process  of  heating,  is  usually  produced  from  the  furnace 
being  urged  to  a  much  greater  heat  than  is  necessary  for  welding 
the  iron ;  in  fact,  the  outside  first,  and,  if  the  heat  be  not  checked, 
the  whole  of  the  mass,  is  reduced  to  a  pasty  or  partially  fluid  con- 
dition. The  structure  of  the  iron  is  thus  entirely  changed ;  and  in 
the  process  of  cooling  the  mass,  crystallization  takes  place  in  the 
same  manner  as  with  other  substances  which  crystallize  in  passing 
from  the  fluid  to  the  solid  state.  Under  these  circumstances,  the 
iron  may  be  injured — in  other  words,  it  may  be  burned :  but  we 
are  not  to  suppose  that  such  a  result  is  either  inevitable  or  by  any 
means  common ;  on  the  contrary,  the  heat  necessary  to  produce  the 
evil  is  with  difficulty  obtained  in  our  ordinary  furnaces,  under  the 
most  favorable  circumstances. 

Some  years  ago  the  experiment  was  tried  at  the  Mersey  Steel 
Works  of  fusing  wrought-iron,  with  the  idea  of  casting  it  into  such 
shapes  as  "  cranks,"  "  cross-heads,"  and  other  forms  required  by 
engineers.  They  succeeded  perfectly  in  obtaining  excellent  castings : 
but  it  was  found  that  the  deterioration  of  the  structure  of  the  iron 
in  passing  from  the  fluid  to  the  solid  state  was  such,  that  the  work 
produced  had  little  more  strength  than  ordinary  cast-iron.  Of 
course,  the  manufacture  was  at  once  given  up.  But  in  the  appear- 
ance of  the  fracture  of  the  ingots  resulting  from  Mr.  Bessemer's 
experiments  at  Baxter-house,  there  was  a  great  similarity  between 
it  and  the  results  obtained  in  melting  scrap  wrought-iron. 

Mr.  Mallet,  in  his  work  (Note  E, page  251),  says: — "Late  ex- 
perience has  shown  me  that  in  very  large  cylindrical  masses  of 
forged  wrought-iron  (i.  e.  of  three  feet  diameter  and  upwards), 
amongst  the  other  abnormal  circumstances  involved  in  their  pro- 
duction, is  that  of  their  frequently  rending  or  tearing  internally  in 
planes  nearly  parallel  with,  and  about  the  axis,  though  not  always 
in  it,  presenting  a  character  similar  to  those  described  in  section 
217  ;  the  cause  appears  to  be,  that  in  the  progress  of  cooling  such  a 
mass  the  exterior  cools  first  and  becomes  rigid,  while  the  internal 
portions  are  still  red-hot  and  soft.  The  external  parts  contract  as 
they  cool,  but  they  already  grasp,  in  perfect  contact,  the  still  hot 


ON   WROUGHT   IRON   IN   LARGE   MASSES. 


127 


Fig.  82. 


interior ;  the  exterior  therefore  cannot  contract  fully,  but  becomes 
solid  under  constraint  circumferentially,  partly  itself  extended  in 
virtue  of  its  compressing  the  still  hot  and  soft  interior.  The  latter 
at  length  also  becomes  cold  and  rigid ;  but  its  contraction  is  now 
resisted  by  the  rigid  arch  of  the  exterior  with  which  it  is  surrounded. 
The  contraction  of  the  interior,  therefore,  is  limited  to  taking  place 
radially  outwards  from  the  centre ;  and  thus  the  mass  rends  itself 
asunder  in  some  one  or  more  planes  parallel  to  the  axis  of  the 
cylinder. 

"Inacylindric  mass  of  forged  iron,  varying  from  24  to  36  inches 
in  diameter,  rents  of  18  inches  in  width 
across  a  diameter  were  found,  with  jag- 
ged counterpart  surfaces  clearly  torn  as- 
under, and  about  fths  of  an  inch  apart  at 
the  widest  or  central  part;  the  fact  is 
most  instructive  as  to  the  enormous  in- 
ternal strains  that  must  exist  from  like 
causes  in  cast-iron  guns  and  mortars  of 
larje  size." 

We  give  a  sketch  (Fig.  82)  of  the  form 
of  this  forging,  showing  the  faults  or  "fis- 
sures" that  were  found  in  it,  and  which 
no  doubt  took  place  from  contraction  after 
the  piece  had  left  the  hammerman's  hands 
perfectly  sound. 

When  !he  forging  was  cooling,  the 
part  D  would  of  course  cool  first ;  and  as 
there  was  no  great  differential  diameter 
between  D  and  B,  the  differential  con- 
traction was  not  greater  than  the  elns- 
ticity  of  the  materials  permitted:  but  the 
sudden  and  great  difference  in  the  diam- 
eters B  and  A  caused  the  forging  at  B 
to  be  comparatively  cool;  whilbi  the  lorg- 
ing  at  A  had  very  considerable  beat,  the 
parts  of  the  forging  at  B  and  D,  being 
nearly  cold,  became  rigid  and  unalter- 
able, constituting  a  very  strong  arch, 
which  prevented  the  forging  from  con- 
tracting in  a  regular  manner. 

If  this  forging  had  been  of  one  uni- 
form  cylindrical    shape,   these   fissures 
would  not  have  taken  place,  as  the  con- 
traction would  have  been  uniform  throughout,  at  the  same  time  the 
conducting  power  of  iron  is  sufficient  to  allow  of  the  heat  passing 
from  the  interior  to  the  outside  with  sufficient  rapidity  to  prevent 
any  fissure  or  unsoundness  taking  place  in  the  forging. 

Mr.  Mallet  proceeds  to  say — "It  is  probably  from  this  cause  that 
more  or  less  hollowncss  is  found  in  tlio  centre  of  almost  every  large 


123  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

forging,  greater  i  n  proportion  as  the  forging  is  larger.  The  difficulty 
is  one  not  easily  overcome.  Very  slow,  and,  as  far  as  possible,  uni- 
form cooling  of  the  whole  mass  in  an  annealing  oven,  suggests  itself 
as  one  remedy;  but  this  has  disadvantages  in  enlarging  the  crystal- 
line development  of  the  metal,  or  providing  a  central  cylindrical 
opening,  so  as  to  cool  the  circumference  and  the  centre  together." 

Here,  at  last,  we  come  to  a  tangible  danger  to  be  feared  in  the 
manufacture  of  large  forgings,  provided  that  due  care  and  atten- 
tion be  not  paid  to  its  proper  manipulation.  But  this  danger  is 
also  common  to  castings;  being  created  not  by  equal,  but  by  dif- 
ferential contraction.  There  is  nothing  more  to  be  dreaded  in 
casting  metals  of  any  sort,  but  more  especially  those  in  which  the 
contraction  is  great,  than  that  any  part  of  the  casting  should  be 
suddenly  reduced  or  increased  in  size.  When  this  is  the  case, 
what  the  founders  call  "  a  draw"  evidently  takes  place ;  and  the 
same  result  is  observed  in  large  forgings,  from  the  cooling  of  the 
smaller  portions  before  the  larger.  In  such  a  case  as  this,  let  us  fol- 
low the  practice  of  the  engineer  and  founder,  who,  from  experi- 
ence and  long  practice,  discourage  such  shapes  as  are  found  im- 
practicable, and  make  such  modifications  in  their  plans  as  shall  do 
away  with  these  differential  results. 

Whilst  Mr.  Mallet's  work  was  passing  through  the  press,  and 
without  any  communication  frorn^  him,  the  maker  of  the  forgings 
he  mentions,  after  three  failures,  overcame  the  difficulty  in  the 
manner  proposed :  viz.,  by  making  a  cylindrical  opening  in  the 
centre,  which  allowed  the  interior  of  the  forgings  to  cool  as  rapidly 
as  the  external  ring,  and  which  permitted  the  necessary  contrac- 
tion without  producing  fissures.  To  endeavor  to  overcome  the 
difficulties  incident  to  an  important  manufacture,  which  is  still  in 
its  infancy,  appears  to  be  much  preferable  to  the  theory  and  max- 
ims of  the  "  Ho  w-not- to-do-it"  school,  who  would  sit  quietly  down 
under  a  difficulty  without  attempting  to  remove  it. 

In  the  Report,  made  by  a  Committee  of  the  Franklin  Institute, 
on  the  bursting  of  the  wrought-iron  gun  on  board  the  United 
States  steam-frigate  "Princeton,"  the  following  facts  were  elicited: 

"1.  The  iron  of  which  the  gun  was  principally  made  was  capa- 
ble of  being  rendered  of  a  good  quality  by  sufficient  working. 

"2.  From  the  state  in  which  the  iron  was  put  into  the  gun,  it 
was  not  in  a  proper  condition  for  the  purpose  to  which  it  was  ap- 
plied. 

"  3.  The  metal,  as  it  existed  in  the  gun,  was  decidedly  bad. 

"4.  As  to  the  manufacture  of  the  gun,  the  welding  was  imperfect. 

"These  facts  relate  exclusively  to  the  gun  submitted  to  the  ex- 
amination  of  the  committee,  and  they  are  derived  from  immediate 
experiments  and  observation.  But  besides  giving  these  to  the 
public,  the  committee  felt  themselves  bound  to  express  the  opinion, 
that  in  the  present  state  of  the  arts  the  use  of  wrought-iron  guns 
of  large  calibre,  made  on  the  same  plan  as  the  gun  now  under  ex- 
amination, ought  to  be  abandoned  for  the  following  reasons : 


ON  WROUGHT-IRON   IN   LARGE   MASSES.  129 

"  1.  The  practical  difficulty,  if  not  impossibility,  of  welding  such 
a  large  mass  of  iron,  so  as  to  insure  perfect  soundness  and  uni- 
formity throughout. 

"  2/The  uncertainty  that  will  always  prevail  in  regard  to  imper- 
fections in  the  welding.  And, 

"  3.  From  the  fact  that  iron  decreases  in  strength  from  long  ex- 
posure to  the  intense  heat  necessary  in  making  a  gun  of  this  size, 
without  a  possibility  of  restoring  the  fibre  by  hammering  with  the 
hammer  at  present  in  use  in  this  country.  At  the  same  time  the 
committee  would  not  wish  to  be  understood  as  expressing  any 
opinion  whether  the  construction  of  a  safe  wrought-iron  gun  upon 
some  other  plan  is  practicable  or  otherwise,  in  the  present  state  of 
the  arts,  inasmuch  as  this  subject  has  not  been  referred  to  them  by 
the  Department." 

"We  are  sorry  that  Mr.  Mallet  thinks  it  necessary  to  add  to  this 
Report,  which  he  quotes  at  length  in  his  valuable  work  on  the 
"  Construction  of  Artillery,"  the  following  remarks : 

"  Nothing  can  more  strikingly  show  the  deteriorating  effects  of 
forging  in  large  masses  (however  done)  upon  the  tenacity  of 
wrought-iron,  than  the  fact  of  the  preceding  Report,  nor  the  un- 
certainty of  the  process  as  respects  welding.  That  the  latter  diffi- 
culty may  be  greatly  mitigated  (though  it  cannot  be  removed)  by 
pre-eminent  skill  on  the  part  of  the  hammerman,  is  proved  by  the 
success  of  the  Mersey  Steel  Company  in  the  duplicate  perfected  by 
them  of  the  gun  which  failed  for  the  '  Princeton,'  and  still  more 
in  the  stupendous  and  apparently  perfect  forging  they  have  now 
almost  finished  into  a  gun  for  the  Government,  no  doubt  by  far 
the  largest  ever  made  in  one  piece,  being  13J  feet  length  of  chase, 
13  inches  calibre,  14  or  15  inches  thick  at  the  charge,  and  about  9 
inches  at  the  muzzle,  a  solid  shot  of  which  will  weigh  300  Ibs." 
Mr.  Mallet  thus  gives  the  weight  of  his  authority  (for  which  we 
entertain  the  greatest  respect)  to  sentiments  which,  in  our  opinion, 
hardly  need  any  further  refutation  than  the  facts  which  he  himself 
mentions. 

The  several  failures  in  the  manufacture  of  wrought-iron  guns 
should  not  be  a  matter  of  surprise  ;  for  it  is  hardly  reasonable  to 
expect  immediate  success  in  any  new  fabrication.  How  many 
failures,  it  might  he  asked,  occurred  before  cast-iron  guns  were 
brought  to  the  comparative  perfection  they  have  now  reached? 
When  we  consider  that  an  attempt  has  been  successfully  made  to 
construct  two  of  the  largest  guns  ever  attempted  of  wrought-iron, 
without  having  had  any  failure  to  record,  we  think  it  hardly  pro- 
bable that  failure  should  occur  where  sufficient  skill  in  workman- 
ship is  used,  and  with  it  added  experience.  It  would,  indeed,  be 
somewhat  strange,  if,  with  additional  experience,  less  successful 
results  were  to  be  obtained  than  in  the  first  comparatively  novel 
experiments. 

One  of  the  most  common  forms  of  real  crystallization  results 
from  what  is  technically  called  "  hammer-hardening."  In  the  year 
9 


130  THE   PEACTICAL   METAL-WOKKER's  ASSISTANT. 

1854,  at  the  meeting  of  the  British  Association  in  Liverpool,  a 
paper  was  read  by  the  writer  of  this  article  on  the  subject  of  crys- 
tallization of  iron  under  certain  circumstances.  He  selected  a 
piece  of  good,  tough,  fibrous  bar-iron,  which  he  tested  by  treating 
in  the  usual  manner.  He  then  heated  it  to  a  full  red  heat,  and 
hammered  it  by  light,  rapid,  tapping  blows,  until  it  was  what  is 
called  "  black-cold."  After  it  was  allowed  to  cool,  he  again  broke 
it,  and  found  that  the  structure  of  the  iron  was  entirely  changed; 
and  that,  instead  of  bending  nearly  double  without  fracture,  and, 
when  the  fracture  did  occur,  breaking  with  a  fine,  silky  fibre,  an 
entire  alteration  had  taken  place,  and  the  bar  was  of  a  rigid,  brit- 
tle, sonorous  character,  incapable  of  bending  in  the  slightest  de- 
gree, but  breaking  with  a  glassy,  crystallized  appearance.  By 
simply  heating  the  bar  to  the  same  red-heat  again,  the  fibre  was 
restored  exactly  as  before.  This  change  in  the  structure  of  iron 
has  been  observed  in  railway  axles  and  chains ;  and  we  believe 
that  it  is  now  customary,  in  some  manufactories,  to  anneal  such 
articles  as  are  exposed  to  any  jar  or  percussion,  at  regular  periods, 
and  with  a  beneficial  result.  Now  this  crystallization  is  particu- 
larly to  be  dreaded  in  forgings,  for,  unless  great  care  is  used,  this 
error  of  "  hammer-hardening"  will  often  take  place — sometimes 
from,  the  vanity  of  the  forge-man,  who  is  naturally  desirous  to  turn 
out  a  pretty  well-finished  forging ;  at  other  times,  as  is  more  gen- 
erally the  case,  from  the  requisition  of  the  engineer,  who,  without 
thinking  of  the  result,  wishes  to  have  his  forging  delivered  to  him 
as  nearly  as  possible  to  the  finished  size  ;  and  when,  as  is  often  the 
case,  a  very  small  allowance  or  margin  is  given  between  the  forged 
and  finished  dimensions,  the  forge-man  is  under  the  necessity  of 
working  his  iron  much  colder  than  is  consistent  with  a  due  regard 
to  strength.  It  is  very  true  that  some  forge-men  will  work  much 
nearer  to  the  sizes  given  them  than  others,  and  still  avoid  the  dan- 
gerous error  of  cold-hammering ;  but  when  certain  dimensions  are 
a  sine  qua  non,  inferior  workmen,  to  keep  anywhere  near  the  mark, 
must  "  cold-hammer"  their  work ;  for  none  but  a  first-rate  work- 
man, and  one  who  has  every  confidence  in  his  own  powers,  dare 
bring  his  iron  down  to  the  required  size  at  full  heat. 

Some  engineers,  and  we  have  known  instances  among  the  most 
eminent,  in  ordering  their  forgings,  have  made  the  remark — "  Pray 
take  care  not  to  finish  the  work  too  cold,  for  we  do  not  care  for  a 
fine  polish  to  our  forgings ;"  and  this  language  we  would  urge  all 
engineers  to  use.  Such  an  instruction  shows  a  true  appreciation 
of  the  danger  of  cold-hammering,  and  a  knowledge  of  his  craft, 
which  it  is  the  object  of  this  work  to  convey  to  all.  But  while  we 
have  a  very  strong  objection  to  cold-hammered  forgings,  we  should 
be  sorry  to  be  understood  as  encouraging  that  slovenly  description 
of  forging,  which  leaves  the  pieces  so  clumsy  and  unsightly  as  to 
require  more  than  a  necessary  amount  of  cutting  or  turning.  This 
is  an  error  that  ought  also  to  be  avoided.  If  proper  care  and 
attention  were  paid  to  the  quality  of  the  material  used,  as  well  as 


GENERAL   EXAMPLES   OF   WELDING.  131 

to  the  workmanship,  we  should  have  fewer  break-downs  in  our 
sea-going  steamers,  and  might,  with  perfect  safety  and  great  advan- 
tage, reduce  the  weight  of  those  parts  that  are  made  of  wrought- 
iron.  In  the  selection  of  forgings,  the  cheapest  are  generally  a 
long  way  from  being  the  least  costly ;  for  the  extra  weight  of  mate- 
rial used,  often  brings  the  actual  cost  up  to  a  level  with  the  dearer, 
but  better-finished  and  lighter  forgings.  Where  cheapness  of  first 
cost  is  the  rule,  though  accepted  as  the  cheapest,  it  will,  in  all 
probability,  be  the  dearest  in  the  end. 

In  concluding  this  chapter,  we  would  observe,  that  the  opin- 
ions and  facts  here  developed  (although  the  result  of  long  practical 
experience)  have  been  put  together  at  a  short  notice,  during  the 
pressure  of  onerous  business  engagements,  which  permitted  but 
little  time  to  be  devoted  to  the  subject.  The  author  does  not  for  a 
moment  pretend  to  treat  this  important  subject  in  the  scientific 
manner  that  it  deserves  ;  but,  when  requested,  he  gave  his  humble 
assistance  to  further,  though  in  a  slight  degree,  the  development 
of  knowledge  on  a  subject  which  has  hardly  ever  received  the 
attention  of  those  practically  competent  to  write  upon  it ;  but 
which,  he  is  convinced,  is  of  great  and  growing  importance  to  the 
country,  as  a  national  manufacture  in  which  it  stands  proudly  pre- 
eminent. 

Should,  however,  the  few  remarks  which  we  have  put  together 
awaken  more  inquiry,  and  further  investigation  of  the  subject,  by 
those  who  have  leisure  and  ability  to  pursue  it,  the  author  will  re- 
joice that  his  humble  endeavors  have  not  been  altogether  in  vain. 


CHAPTER  VIII. 

GENERAL   EXAMPLES   OF   WELDING. 

THE  former  illustrations  of  forging  have  been  to  some  extent  de- 
scriptive of  such  works  as  could  be  made  from  a  single  bar  of 
iron,  on  purpose  that  the  examples  to  be  advanced  in  welding  or 
joining  together  two  pieces  of  iron  by  heat,  technically  called 
"shutting  together"  or  "  shutting -up"  might  be  collected  at  one 
place. 

There  are  several  ways  of  accomplishing  this  operation,  and 
which  bear  some  little  analogy  to  the  joints  employed  in  carpentry ; 
more  particularly  that  called  scarfing,  used  in  the  construction  of 
long  beams  and  girders  by  joining  two  shorter  pieces  together  end- 
ways, with  sloping  joints,  which  in  carpentry  are  interlaced  or 
mortised  together  in  various  ways,  and  then  secured  by  iron  straps 
or  bolts.  In  smith's  work,  likewise,  the  joinings  are  called  scarfs, 
but  from  the  adhesive  nature  of  the  iron  when  at  a  suitable  tern- 


132 


THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 


perature,  the  accessories  called  for  in  carpentry,  such  as  glue,  bolts, 
straps  and  pins,  are  no  longer  wanted. 

The  example,  Fig.  58,  was  left  unfinished,  but  we  will  proceed 
to  show  the  mode  of  joining  the  two  cylindrical  ends  of  the  work. 
The  scarfs  required  for  the  "shut,"  are  made  by  first  upsetting  or 
thickening  the  iron  by  blows  upon  its  extremity,  to  prepare  it  for 
the  loss  it  will  sustain  from  scaling  off,  both  in  the  fire  and  upon 
the  anvil,  and  also  in  the  subsequent  working  upon  the  joint.  It 
is  next  rudely  tapered  off  to  the  form  of  a  flight  of  steps,  as  shown 
in  Figs.  83  and  84,  and  the  sides  are  slightly  beveled  or  pointed, 
as  in  Fig.  84,  the  proportions  being  somewhat  exceeded  to  render 
the  forms  more  apparent. 


84 


» The  two  extremities  are  next  heated  to  the  point  of  ignition ; 
and  when  this  is  approached,  a  little  sand  is  strewed  upon  each 
part,  which  fuses  and  spreads  something  like  a  varnish,  and  parti- 
ally defends  them  from  the  air ;  the  heat  is  proper  when,  notwith- 
standing the  sand,  the  iron  begins  to  burn  away  with  vivid  sparks. 
The  two  men  then  take  each  one  piece,  strike  them  forcibly  across 
the  anvil  to  remove  any  loose  cinders,  place  them  in  their  true 
positions,  exactly  as  in  Fig.  83,  and  two  or  three  blows  of  the 
small  hammer  of  the  principal  or  fireman  stick  them  together ;  the 
assistant  then  quickly  joins  in  with  the  sledge-hammer,  and  the 
smoothing  off  and  completion  of  the  work  are  soon  accomplished. 

It  is  of  course  necessary  to  perform  the  work  with  rapidity,  and 
literally  "  to  strike  whilst  the  iron  is  hot ;"  the  smith  afterwards 
jumps  the  end  of  the  rod  upon  the  anvil,  or  strikes  it  endways 
with  the  hammer ;  this  proves  the  soundness  of  the  joint,  but  it  is 
mostly  done  to  enlarge  the  part,  should  it  during  the  process  have 
become  accidentally  reduced  below  the  general  size.  The  sand 
appears  to  be  quite  essential  to  the  process  of  welding,  as  although 
the  heat  might  be  arrived  at  without  its  agency,  the  surface  of  the 
metal  would  become  foul  and  covered  with  oxide  when  unprotected 
from  the  air — at  all  events  common  experience  shows  that  it  is 
always  required.  The  scarf  joint,  shown  in  Figs.  83  and  84,  is 
commonly  used  for  all  straight  bars,  whether  flat,  square  or  round, 
when  of  medium  size. 


GENERAL   EXAMPLES    OF   WELDING.  133 

In  very  heavy  works  the  welding  is  principally  accomplished 
within  the  fire :  the  two  parts  are  previously  prepared  either  to  the 
form  of  the  tongue  or  split  joint,  Fig.  85,  or  to  that  of  the  butt  joint, 
Fig.  86,  and  placed  in  their  relative  positions  in  a  large  hollow 
fire.  When  the  two  parts  are  at  the  proper  heat,  they  are  jumped 
together  endways,  which  is  greatly  facilitated  by  their  suspension 
from  the  crane,  and  they -are  afterwards  struck  on  the  ends  with 
sledge-hammers,  a  heavy  mass  being  in  some  cases  held  against 
the  opposite  extremity  to  sustain  the  blows ;  the  heat  is  kept  up, 
and  the  work  is  ultimately  withdrawn  from  the  fire,  and  finished 
upon  the  anvil. 

The  butt  joint,  Fig.  86,  is  materially  strengthened,  when,  as  it  is 
usually  the  case  for  the  paddle  shafts  of  steam  vessels  and  similar 
works,  the  joint  whilst  still  large  is  notched  in  on  three  or  four 
sides,  and  pieces  called  stick-in  pieces,  dowels,  or  charlim,  one  of 
which  is  represented  by  the  dotted  lines,  are  prepared  by  another 
fire,  and  laid  in  the  notches ;  the  whole,  when  raised  to  the  weld- 
ing heat,  is  well  worked  together  and  reduced  to  the  intended 
size ;  this  mingles  all  the  parts  in  a  very  substantial  manner.  For 
the  majority  of  works,  however,  the  scarf  joint,  Fig.  83,  is  used, 
but  the  stick-in  pieces  are  also  occasionally  employed,  especially 
when  any  accidental  deficiency  of  iron  is  to  be  feared. 

When  two  bars  are  required  to  form  a  T  joint,  the  transverse 
piece  is  thinned  down  as  at  a,  in  Fig.  87;  for  an  angle  or  corner  the 
form  of  b  may  be  adopted ;  but  c,  in  which  each  part  is  cut  off  ob- 
liquely, is  to  be  preferred.  The  pieces  a,  b,  c,  are  represented  up- 
side down,  in  order  that  the  ridges  set  down  on  their  lower  sur- 
faces may  be  seen.  4  In  most  cases  when  two  separate  bars  are  to 
be  joined,  whatever  the  nature  of  the  joint,  the  metal  should  be 
first  upset,  and  then  set  down  in  ridges  on  the  edge  of  the  anvil, 
or  with  a  set  hammer,  as  the  plain  chamfered  or  sloping  sur- 
faces are  apt  to  slide  asunder  when  struck  with  the  hammer,  and 
prevent  the  union.  When  a  T  joint  is  made  of  square  or 
thick  iron,  the  one  piece  is  upset,  and  moulded  with  the 
fuller  much  in  the  form  of  the  letter ;  it  is  then  welded  against 
the  flat  side  of  the  bar :  such  works  are  sometimes  welded  with 
dowel  or  tenon  joints,  but  all  the  varieties  of  method  cannot  be 
noticed. 

There  are  many  works  in  which  the  opposite  edges,  or  the  ends 
of  the  same  piece,  require  to  be  welded.  In  these  the  risk  of  the 
two  parts  sliding  asunder  scarcely  exists,  and  the  scarfs  are  made 
with  a  plain  chamfer,  or  simply  to  overlap  or  fold  together  with- 
out any  particular  preparation. 

Of  the  last  kind  Fig.  63  may  be  taken  as  an  example,  in  which 
the  parts  have  no  disposition  to  separate.  In  this  and  similar  cases 
the  smith  often  leaves  the  parts  slightly  open,  in  order  that  the 
very  last  process  before  welding  may  be  the  striking  the  whole 
edgeways  upon  the  anvil,  to  drive  out  any  loose  scales,  cinders  or 
sand,  situated  between  the  joints :  which  if  allowed  to  remain 


134  -THE  PRACTICAL   METAL-WORKERS   ASSISTANT. 

would  be  either  inclosed  amidst  the  sound  parts  of  the  work,  or 
would  partially  prevent  the  union. 

In  works  that  have  accidentally  broken  in  the  welded  part,  the 
fracture  will  be  frequently  seen  to  have  arisen  from  some  dirty 
matter  having  been  allowed  to  remain  between  them,  on  which 
account,  shuts  or  welded  joints  extending  over  a  large  surface  are 
often  less  secure  than  those  of  smaller  area,  from  the  greater  risk 
of  their  becoming  foul.  In  fact,  throwing  a  little  small  coal  be- 
tween the  contiguous  surfaces  of  work  not  intended  to  be  united, 
is  a  common  and  sometimes  a  highly  essential  precaution  to  pre- 
vent them  from  becoming  welded. 

The  conical  sockets  of  socket  chisels,  garden  spuds,  and  a  variety 
of  agricultural  implements,  are  formed  out  of  a  bar  of  flat  iron, 
which  is  spread  out  sideways  or  to  an  angle,  with  the  pane  of  the 
hammer,  and  then  bent  within  a  semi-circular  bottom  tool  also,  by 
the  pane  of  the  hammer,  to  the  form  of  Fig.  88 ;  after  which  the 
sockets  are  still  more  curled  up  by  blows  on  the  edges,  and  are 


Figs. 


perfected  upon  a  taper-pointed  mandrel,  so  that  the  two  edges 
slightly  overlap  at  the  mouth  of  the  socket,  and  meet  pretty  uni- 
formly elsewhere,  as  in  Fig.  89,  and  lastly,  about  an  inch  or  more 
at  the  end  is  welded.  Sometimes  the  welding  is  continued  through- 
out the  length,  but  more  commonly  only  a  small  portion  of  the 
extremity  is  thus  joined,  and  the  remainder  o%the  edges  are  drawn 
together  with  the  pane  of  the  hammer. 

In  making  wrought-iron  hinges,  two  short  slits  are  cut  length- 
ways and  nearly  through  the  bar,  towards  its  extremity.  The  iron 
is  then  folded  round  a  mandrel,  set  down  close  in  the  corner,  and 
the  two  ends  are  welded  together.  To  complete  the  hinge,  it  only 
remains  to  cut  away  transversely,  either  the  central  piece  or  the 
two  external  pieces  to  form  the  knuckles,  and  the  addition  of  the 
pin  or  pivot  finishes  the  work. 

Musket  barrels,  when  made  entirely  by  hand,  were  forged  in  the 
form  of  long  strips  about  a  yard  long  and  four  inches  wide,  but 
taper  both  in  length  and  width,  which  were  bent  round  a  cylin- 
drical mandrel  until  their  edges  slightly  overlapped.  They  were 
then  welded  at  three  or  four  heats  by  introducing  the  mandrel 
within  them  instantly  on  their  removal  from  the  fire  at  the  proper 
heat,  in  order  to  prevent  the  sides  of  the  tube  from  being  pressed 
together  by  the  blows  of  the  hammer. 

They  have  been  subsequently  and  are  now  universally  welded 
by  machinery,  at  one  heat ;  and  whilst  of  the  length  of  only  one 
foot,  as  on  removal  from  the  fire  the  mandrel  is  quickly  intro- 
duced, and  the  two  are  passed  through  a  pair  of  grooved  rollers. 
They  are  afterwards  extended  to  the  full  length  by  similar  means, 


GENERAL   EXAMPLES   OF   WELDING.  135 

but  at  a  lower  temperature,  so  that  the  iron  is  not  so  much  injured 
as  when  thrice  heated  to  the  welding  point. 

The  twisted  barrels  are  made  out  of  long  ribands  of  iron  wound 
spirally  around  a  mandrel,  and  welded  on  their  edges  by  jumping 
them  upon  the  ground,  or  rather  on  an  anvil  embedded  therein. 
The  plain  stub  barrels  are  made  in  this  manner,  from  iron  manu- 
factured from  a  bundle  of  stub-nails,  welded  together  and  drawn 
out  into  ribands,  to  insure  the  possession  of  a  material  most  thor- 
oughly and  intimately  worked.  The  Damascus  barrels  are  made 
from  a  mixture  of  stub-nails  and  clippings  of  steel  in  given  pro- 
portions, puddled  together,  made  into  a  bloom,  and  subsequently 
passed  through  all  the  stages  of  the  manufacture  of  iron  already 
explained :  to  obtain  an  iron  that  shall  be  of  unequal  quality  and 
hardness,  and  therefore  display  different  colors  and  markings  when 
oxidized  or  browned. 

Other  twisted  barrels  are  made  in  the  like  manner,  except  that 
the  bars  to  form  the  ribands  are  twisted  whilst  red-hot  like  ropes, 
some  to  the  right,  others  to  the  left,  and  which  are  sometimes  again 
laminated  together  for  greater  diversity.  They  are  subsequently 
again  drawn  into  the  ribands  and  wound  upon  the  mandrel,  and 
frequently  two  or  three  differently-prepared  pieces  are  placed  side 
by  side  to  form  the  complex  and  ornamental  figures  for  the  barrels 
of  fowling-pieces,  described  as  "stub-twist,  wire-twist,  Damascus- 
twist,"  etc. 

A  method  amongst  others  of  the  formation  of  the  Damascus  gun- 
barrels  :  By  arranging  twenty-five  thin  bars  of  iron  and  mild  steel 
in  alternate  layers,  welding  the  whole  together,  drawing  it  down 
small,  twisting  it  like  a  rope,  and  again  welding  three  such  ropes, 
for  the  formation  of  the  riband,  which  is  then  spirally  twisted  to 
form  a  barrel,  that  exhibits,  when  finished  and  acted  upon  by  acids, 
a  diversified  laminated  structure,  resembling  when  properly  man- 
aged an  ostrich  feather. 

When  the  illumination  by  gas  was  first  introduced  in  the  large 
way,  the  old  musket-barrels,  laid  by  in  quiet  retirement  from  the 
fatigues  of  war,  were  employed  for  the  conveyance  of  gas ;  and 
by  a  curious  coincidence,  various  iron  foundries  desisted  in  a  great 
measure  from  the  manufacture  of  iron  ordnance,  and  took  up  the 
peaceful  employment  of  casting  pipes  for  gas  and  water. 

The  breech  ends  of  the  musket-barrels  were  broached  and  tapped, 
and  the  muzzles  were  screwed  externally  to  connect  the  two 
without  detached  sockets.  From  the  rapid  increase  of  gas  illu- 
mination, the  old  gun-barrels  soon  became  scarce,  and  new  tubes 
with  detached  sockets,  made  by  the  old  barrel-forgers,  were  first 
resorted  to.  This  led  to  a  series  of  valuable  contrivances  for  the 
manufacture  of  the  wrought-iron  tubes,  under  which  the  tubes 
were  first  bent  up  by  hand-hammers  and  swages,  to  bring  the 
edges  near  together ;  and  they  were  welded  between  semi-circular 
swages,  fixed  respectively  in  the  anvil,  and  the  face  of  a  small  tilt- 
hammer  worked  by  machinery,  by  a  series  of  blows  along  the 


136  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

tube,  either  with  or  without  a  mandrel.  The  tube  was  completed 
on  being  passed  between  rollers  with  half-round  grooves,  which 
forced  it  over  a  conical  or  egg-shaped  piece  at  the  end  of  a  long 
bar,  to  perfect  the  interior  surface. 

Various  steps  of  improvement  have  been  since  made.     For  in- 
stance, the  skelps  were  bent  at  two  squeezes,  first  to  the 


cylindrical  and  then  to  the  tubular  form  (preparatory  to  welding), 
between  a  swage-tool  five  feet  long  worked  by  machinery.  The 
whole  process  was  afterwards  carried  on  by  rollers,  but  abandoned 
on  account  of  the  unequal  velocity  at  which  the  greatest  and  least 
diameters  of  the  rollers  travelled. 

In  the  present  method  of  manufacturing  the  patent  welded  tube, 
the  end  of  the  skelp  is  bent  to  the  circular  form,  its  entire  length 
is  raised  to  the  welding  heat  in  an  appropriate  furnace,  and  as  it 
leaves  the  furnace  almost  at  the  point  of  fusion,  it  is  dragged  by 
the  chain  of  a  draw-bench,  after  the  manner  of  wire,  through  a 
pair  of  tongs  with  two  bell-mouthed  jaws.  Thes.e  are  opened  at 
the  moment  of  introducing  the  end  of  a  skelp,  which  is  welded 
without  the  agency  of  a  mandrel. 

By  this  ingenious  arrangement  wrought-iron  tubes  may  be  made 
from  the  diameter  of  six  inches  internally  and  about  one-eighth  to 
three-eighths  of  an  inch  thick,  to  as  small  as  one-quarter  of  an 
inch  diameter  and  one-tenth  bore  ;  and  so  admirably  is  the  joining 
effected  in  those  of  the  best  description,  that  they  will  withstand 
the  greatest  pressure  of  gas,  steam  or  water,  to  which  they  have 
been  subjected,  and  they  admit  of  being  bent  both  in  the  heated 
and  cold  state  almost  with  impunity.  Sometimes  the  tubes  are 
made  one  upon  the  other  when  greater  thickness  is  required  ;  but  . 
these  stout  pipes,  and  those  larger  than  three  inches,  are  compara- 
tively but  little  used.  The  wrought-iron  tubes  of  hydrostatic 
presses,  which  measure  about  half  an  inch  internally,  and  one- 
fourth  to  three-eighths  of  an  inch  thick  in  the  metal,  are  fre- 
quently subjected  to  a  pressure  equal  to.  four  tons  on  each  square 
inch. 

Various  articles,  with  large  apertures,  are  made  not  by  punch- 
ing or  cutting  out  the  holes,  but  by  folding  the  metal  around  the 
beak  iron  and  finishing  them  upon  a  triblet  of  the  appropriate 
figure.  Thus  the  complete  smithy  is  generally  furnished  with  a 
series  of  cones  turned  in  the  lathe,  for  making  rings,  the  ends  of 
which  are  folded  together  and  welded,  such  as  Fig.  90.  The  same 
rings  when  made  of  such  cast-steel  as  does  not  admit  of  being 
welded,  are  first  punched  with  a  small  hole  and  gradually  thinned 
out  by  blows  around  the  margin  until  they  reach  the  diameter 
sought.  But  this,  like  numerous  other  works,  requires  considera- 
ble forethought  to  proportion  the  quantity  of  the  material  to  its 
ultimate  form  and  bulk,  so  that  the  work  may  not  in  the  end  be- 
come either  too  slight  or  too  heavy. 

Chains  may  be  taken  as  another  familiar  example  of  welding. 
In  these  the  iron  is  cut  off  with  a  plain  chamfer,  as  from  the  annu- 


GENERAL   EXAMPLES   OF   WELDING.  137 

lar  form  of  the  links  their  extremities  cannot  slide  asunder  when 
struck.  Every  succeeding  link  is  bent,  introduced,  and  finally 
welded.  In  some  of  these  welded  chains  the  links  are  no  more 
than  half  an  inch  long,  and  the  iron  wire  one-eighth  of  an  inch 
diameter.  Several  inches  of  such  chain  are  required  to  weigh  one 
pound.  These  are  made  with  great  dexterity  by  a  man  and  a  boy 
at  a  small  fire.  The  curbed  chains  are  welded  in  the  ordinary  form 
and  twisted  afterwards,  a  few  links  being  made  red-hot  at  a  time 
for  the  purpose. 

The  massive  cable-chains  are  made  much  in  the  same  manner, 
although  partly  by  aid  of  machinery.  The  bar  of  iron,  now  one, 
one  and  a  half,  or  even  two  inches  in  diameter,  is  heated,  and  the 
scarf  is  made  as  a  plain  chamfer  by  a  cutting  machine ;  the  link  is 
then  formed  by  inserting  the  end  of  the  heated  bar  within  a  loop 
in  the  edge  of  an  oval  disk  which  may  be  compared  to  a  chuck 
fixed  on  the  end  of  a  lathe  mandrel.  The  disk  is  put  in  gear  with 
the  steam-engine;  it  makes  exactly  one  revolution,  and  throws 
itself  out  of  motion;  this  bends  the  heated  extremity  of  the  iron 
into  an  oval  figure.  Afterwards  it  is  detached  from  the  rod  with 
a  chamfered  cut  by  the  cutting  machine,  which  at  one  stroke  makes 
the  second  scarf  of  the  detached  link,  and  the  first  of  that  next  to 
be  curled  up. 

The  link  is  now  threaded  to  the  extremity  of  the  chain,  closed 
together,  and  transferred  to  the  fire,  the  loose  end  being  carried  by 
a  traverse  crane.  When  the  link  is  at  the  proper  heat,  it  is  re- 
turned to  the  anvil,  welded,  and  dressed  off  between  top  and  bot- 
tom tools,  after  which  the  cast-iron  transverse  stay  is  inserted,  and 
the  link  having  been  closed  upon  the  stay,  the  routine  is  recom- 
menced. The  work  commonly  requires  three  men,  and  the  scarf 
is  placed  at  the  side  of  the  oval  link,  and  flatway  through  the 
same.  In  similar  chains  made  by  hand  it  is  perhaps  more  cus- 
tomary to  weld  the  link  at  the  crown,  or  small  end. 

The  tires  of  wrought-iron  wheels  for  locomotive  engines  and 
carriages,  are  in  general  bent  to  the  circle  by  somewhat  analogous 
means  to  those  employed  in  chain-making,  as  are  likewise  the 
skelps  for  the  twisted  barrels  of  guns.  The  latter  only  require  a 
mandrel  or  spindle  with  a  winch-handle  at  the  one  extremity,  and 
a  loop  for  the  end  of  the  skelp,  which  is  wound  in  contact  with 
the  mandrel  by  means  of  a  fixed  bar  placed  near  the  same.  Such 
barrels  are  coiled  up  in  three  lengths,  which  are  joined  together 
after  the  spirals  are  welded. 

Wheels  for  railways  display  many  curious  examples  of  smith- 
ing ;  thus  some,  except  the  nave,  are  made  entirely  by  welding ; 
others  are  partly  combined  with  rivets;  in  all  the  nave  or  boss  is  a 
mass  of  cast-iron  usually  poured  around  the  ends  of  the  spokes. 

The  common  practice  of  welding  the  tires  of  railway  wheels  is 
uow  as  follows :  the  tires  are  cut  off  with  ridges  in  the  centre,  so 
as  in  meeting  to  form  two  angular  notches,  into  which  two  thin 
iron  wedges  are  subsequently  welded  radially ;  the  four  parts  thus 


138 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 


united  together  in  the  form  of  a  cross,  make  a  very  secure  joint 
without  the  necessity  for  upsetting  the  iron,  which  would  distort 
the  form  of  the  tire. 

The  succeeding  illustration  of  the  practice  of  forging  will  be  that 
of  the  formation  of  a  hatchet,  Figs.  91  and  92,  which  like  many 
similar  tools  is  made  by  doubling  the  iron  around  a  mandrel,  to 
form  the  eye  of  the  tool ;  it  will  also  permit  the  description  of  some 
other  general  proceedings  and  likewise  the  introduction  of  the  steel 
for  the  cutting  edge. 


Figs.  90 


93  94 


D  H 

In  making  the  hatchet,  a  piece  of  flat  iron  is  selected  of  the  width 
of  A  E,  and  twice  the  length  of  A  D  ;  it  is  thinned  and  extended 
sideways  before  it  is  folded  together,  to  form  the  projections  near 
B  and  F,  by  blows  with  the  pane  of  the  hammer  or  a  round-edged 
fuller,  on  the  lines  A  B  to  E  F,  but  the  metal  must  be  preserved 
of  the  full  thickness  at  the  part  A  E,  to  form  the  poll  of  the  hatchet, 
although  a  piece  of  steel  is  frequently  welded  on  at  that  part  as  a 
previous  step.  The  work  is  then  bent  round  a  mandrel,  Figs.  93 
and  94,  exactly  of  the  section  of  the  eye  as  seen  in  Fig.  92,  and 
the  work  is  welded  across  the  line  B  F ;  the  mandrel  is  again  in- 
troduced, and  the  eye  is  perfected. 

A  slip  of  shear-steel,  equal  in  length  to  D  H,  is  next  inserted  be- 
tween the  two  tails  of  the  iron,  as  yet  of  their  original  size,  up  to 
the  former  weld,  and  all  three  are  welded  together  between  C,  G, 
D,  H :  the  combined  iron  and  steel  are  now  drawn  out  sideways, 
by  blows  of  the  pane  of  the  hammer  on  and  between  C  D  and  G  II, 
to  extend  them  together  to  I  J.  The  tool  is  then  flattened  and 
smoothed  with  the  face  of  the  hammer,  and  the  edges  are  pared 
with  straight  or  circular  chisels  to  the  particular  pattern,  and 
trimmed  with  a  round-faced  hammer,  or  a  top  fuller. 

In  smoothing  off'  the  work,  the  smith  pursues  his  common 
method  of  first  removing  with  a  file  the  hard  black  scales  that 
appear  like  spots  when  the  work  is  removed  from  the  fire;  he 
then  dips  the  hammer  in  the  slake  trough,  and  lets  fall  upon  the 
anvil  a  few  drops  of  the  water  it  picks  up,  the  explosion  of  which 
when  the  red-hot  metal  is  struck  upon  it,  makes  a  smart  report 
and  detaches  the  scales  that 'would  be  otherwise  indented  in  the 
work.  It  should  be  observed  that  the  mandrel,  Fig.  93,  is  pur- 


\ 

GENERAL    EXAMPLES   OF   WELDING.  139 

posely  made  very  taper,  and  is  introduced  into  the  hole  from 
both  sides,  so  that  the  eye  may  be  smaller  in  the  middle ;  when 
therefore  the  handle  of  the  tool  is  carefully  fitted  and  wedged  in, 
the  handle  is,  as  it  were,  dove-tailed,  and  the  tool  can  neither  fly 
oft'  nor  slip  down  the  handle ;  the  same  mode  is  also  adopted  for 
the  heads  of  hammers. 

In  spades,  and  many  similar  implements,  the  steel  is  introduced 
between  the  two  pieces  of  iron  of  which  the  tools  are  made ;  in 
others,  as  plane  irons  and  socket  chisels,  it  is  laid  on  the  outside, 
and  the  'two  are  afterwards  extended  in  length  or  width  to  the 
required  size.  The  ordinary  chisel  for  the  smith's  shop  is  made 
by  inserting  the  steel  in  a  cleft,  as  in  Fig.  85,  and  so  is  also  the 
pane  of  a  hammer ;  but  the  flat  face  of  the  hammer  is  sometimes 
stuck  on  whilst  it  continues  at  the  extremity  of  a  flat  bar  of  steel ; 
it  is  then  cut  off,  and  the  welding  is  afterwards  completed.  At 
other  times  the  face  of  the  hammer  is  prepared  like  a  nail,  with  a 
small  spike  and  a  very  large  head,  so  as  to  be  driven  into  the 
iron  to  retain  its  position,  until  finally  secured  by  the  operation  of 
welding. 

In  putting  a  piece  of  steel  into  the  end  of  an  iron  rod  to  serve 
for  a  centre,  the  bar  is  heated,  fixed  horizontally  in  the  vice,  and 
punched  lengthways  with  a  sharp  square  punch  for  the  reception  of 
the  steel,  which  is  drawn  down  like  a  taper  tang  or  thick  nail,  and 
driven  in ;  the  whole  is  then  returned  to  the  fire,  and  when  at  the 
proper  heat  united  by  welding,  the  blows  being  first  directed  as 
for  forming  a  very  obtuse  cone,  to  prevent  the  piece  of  steel  from 
dropping  out. 

For  some  few  purposes  the  blistered  steel  is  used  for  welding, 
either  to  itself  <5r  to  iron;  it  is  true  the  first  working  under  the 
hammer  in  a  measure  changes  it  to  the  condition  of  shear-steel,  but 
less  efficiently  so  than  when  the  ordinary  course  of  manufacture  is 
pursued,  as  the  hammering  is  found  to  improve  steel  in  a  remark- 
able and  increasing  degree. 

For  the  majority  of  works  in  which  it  is  necessary  to  weld  steel 
to  iron,  or  steel  to  steel,  the  shear,  or  double  shear,  is  exceedingly 
suitable;  it  is  used  for  welding  upon  various  cutting  tools,  as  the 
majority  of  cast-steel  will  not  endure  the  heat  without  crumbling 
under  the  hammer.  Shear-steel  is  also  used  for  various  kinds  of 
springs,  and  for  some  cutting  tools  requiring  much  elasticity. 

It  is  more  usual  to  reserve  the  cast-steel  for  those  works  in  which 
the  process  of  welding  is  not  required,  although  of  late  years  mild 
cast-steel,  or  welding  cast-steel,  containing  a  smaller  proportion  of 
carbon  has  been  rather  extensively  used ;  but  in  general  the 
harder  the  steel  the  less  easily  will  it  admit  of  welding,  and  not 
unfrequently  it  is  altogether  inadmissible. 

The  hard  or  harsh  varieties  of  cast-steel,  are  somewhat  more 
manageable  when  fused  borax  is  used  as  a  defence  instead  of  sand, 
either  sprinkled  on  in  powder  or  rubbed  on  in  a  lump :  and  cast- 
eteel  otherwise  intractable  may  be  sometimes  welded  to  iron  by  first 


140  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

heating  the  iron  pretty  smartly,  then  placing  the  cold  steel  beside 
it  in  the  fire,  and  welding  them  the  moment  the  steel  has  acquired 
its  maximum  temperature,  by  which  time  the  iron  will  be  fully  up 
to  the  welding  heat.  When  both  are  put  into  the  fire  cold  alike, 
the  steel  is  often  spoiled  before  the  iron  is  nearly  hot  enough, 
and  therefore  it  is  generally  usual  to  heat  the  iron  and  steel  sepa- 
rately, and  only  to  place  them  in  contact  towards  the  conclusion 
of  the  period  of  getting  up  the  heat.  In  forging  works  either  of 
iron  or  steel,  the  uniformity  of  the  hammering  tends  greatly  to 
increase  and  equalize  the  strength  of  each  material ;  and  in  steel, 
judicious  and  equal  forging  greatly  lessens  also  the  after-risk  in 
hardening. 

When  cast-steel  has  been  spoiled  by  overheating,  it  may  be  par- 
tially recovered  by  four  or  five  reheatings  and  quenchings  in  water, 
each  carried  to  an  extent  a  little  less  and  less  than  the  first  excess ; 
and  lastly,  the  steel  must  have  a  good  hammering  at  the  ordinary 
red  heat.  Some  go  so  far  as  to  prefer  for  cutting  tools  the  steel 
thus  recovered,  but  this  seems  a  most  questionable  policy,  although 
the  change  wrought  by  this  treatment  is  really  remarkable ;  as  the 
fragment  broken  off  from  the  bar  in  the  spoiled  state,  and  another 
from  the  same  bar  after  part  restoration  and  hardening,  will  ex- 
hibit the  extreme  characters  of  coarse  and  fine. 

The  hammering  I  suspect  to  be  the  principal  requisite,  and  in 
superior  tools  it  should  be  continued  until  the  work  is  nearly  cold, 
to  produce  the  maximum  amount  of  condensation  before  harden- 
ing ;  but  no  hammering  will  restore  the  loss  of  tenacity  consequent 
upon  the  over-heating,  or  even  the  too  frequent  heating,  of  steel, 
without  excess. 

CONCLUDING' REMARKS  ON  FORGING  ;  AND  THE  APPLICATIONS 
OF  HEADING  TOOLS,  SWAGE  TOOLS,  PUNCHES,  ETC. — With  the 
utmost  care  and  unlimited  space,  it  would  have  been  quite  impos- 
sible to  have  conveyed  the  instructions  called  for,  in  forging  the 
thousand  varieties  of  tools,  and  parts  of  mechanism  the  smith  is 
continually  called  upon  to  produce ;  and  all  that  could  be  reason- 
ably attempted  in  this  place,  was  to  convey  a  few  of  the  general 
features  and  practices  of  this  most  useful  and  interesting  branch 
of  industry.  It  is  hoped,  that  such  combinations  of  these  methods 
may  be  readily  arrived  at  as  will  serve  for  the  majority  of  or- 
dinary wants. 

The  smith  in  all  cases  selects  or  prepares  that  particular  form 
and  magnitude  of  iron,  and  also  adopts  that  order  of  proceeding, 
which  experience  points  out  as  being  the  most  exact,  sound,  and 
economical.  In  this  he  is  assisted  by  a  large  assortment  of  vari- 
ous tools  and  moulds  for  such  parts  of  the  work  as  are  often  re- 
peated, or  that  are  of  a  character  sufficiently  general  to  warrant 
the  outlay,  and  to  some  of  which  I  will  advert. 

The  heading  tools,  Figs.  53  and  54,  are  made  of  all  sizes  and 
varieties  of  form ;  some  with  a  square  recess  to  produce  a  square 
beneath  the  head,  to  prevent  the  bolt  from  being  turned  round  in 


GENERAL   EXAMPLES   OF   WELDING.  141 

the  act  of  tightening  its  nut ;  others  for  countersunk  and  round- 
headed    bolts,    with   and    without 
95>  square    shoulders:     many   similar 

heading  tools  are  used  for  all  those 
parts  of  work  which  at  all  resem- 
ble bolts,  in  having  any  sudden  en- 
largement from  the  stem  or  shaft. 
The  holes  in  the  swage  block,  Fig. 
95,  are  used  after  the  manner  of 
heading  tools  for  large  objects  ;  the 
grooves  and  recesses  around  its 
margin,  also  serve  in  a  variety  of 
works  as  bottom  swages  beyond 
the  size  of  those  fitted  to  the  anvil. 
At  the  opposite  extreme  of  the 
heading  tools,  as  to  size,  may  be 
noticed  those  constantly  employed  in  producing  the  smallest  kinds 
of  nails,  brads  and  rivets,  of  various  denominations,  some  of  which 
heading  tools  divide  in  two  parts  like  a  pair  of  spring  forceps  to 
release  the  nails  after  they  have  been  forged. 

The  forge  used  by  the  nail-makers  is  built  as  a  circular  pedestal 
with  the  fire  in  the  centre  and  the  chimney  directly  over  it ;  the 
rock-staff  of  the  bellows  extends  entirely  around  the  forge,  so  that 
one  of  the  four  or  five  persons  who  work  at  the  same  fire  is  con- 
tinually blowing  it,  whence  the  fire  is  always  at  a  heat  proper  for 
welding,  and  which  keeps  the  nails  sound  and  good.  These  kinds 
are  called  wrought  nails  and  brads,  in  contradistinction  to  similar 
nails  cut  out  of  sheet-iron  by  various  processes  of  shearing  and 
punching,  which  latter  kinds  are  known  as  cut  brads  and  nails, 
and  will  be  adverted  to  hereafter. 

The  top  and  bottom  rounding  tools,  Fig.  50,  are  made  of  all 
diameters  for  plain  cylindrical  works :  and  when  they  are  used  for 
objects  the  different  parts  of  which  are  of  various  diameters,  it 
requires  much  care  to  apply  them  equally  on  all  parts  of  the  work, 
that  the  several  circles  may  be  concentric  and  true  one  with  the 
other,  or  possess  one  axis  in  common.  To  insure  this  condition 
some  of  these  rounding  tools  are  made  of  various  and  specific 
forms,  for  the  heads  of  screws,  for  collars,  flanges  or  enlargements, 
which  are  of  continual  occurrence  in  machinery ;  for  the  orna- 
mental swells  or  flanges  about  the  iron  work  of  carriages,  and 
other  works.  Such  tools,  like  the  pair  represented  in  Figs.  96  and 
97,  are  called  swage  or  collar  tools ;  they  save  labor  in  a  most 
important  degree,  and  are  thus  made.  A  solid  mould,  core  or 
striker,  exactly  a  copy  of  the  work  to  be  produced,  is  made  of 
steel  by  hand-forging,  and  then  turned  in  the  lathe  to  the  required 
form,  as  shown  in  Fig.  98. 

The  top  tool  is  first  moulded  to  the  general  form  in  an  appro- 
priate aperture  in  the  swage  block,  Fig.  95,  it  is  faced  with  steel 
like  a  hammer,  and  the  core,  Fig.  98,  is  indented  into  it;  the  blows 


142  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

of  the  sledge-hammer  not  being  given  directly  upon  the  core,  but 
upon  some  hollow  tool  previously  made ;  otherwise  the  core  must 
be  filed  partly  flat  to  present  a  plane  surface  to  the  hammer.  The 
bottom  tool,  which  is  fitted  to  the  anvil,  is  made  in  a  similar  man- 
ner, and  sometimes  the  two  are  finished  at  the  same  time  whilst 


Figs. 


102 


101 


hot,  with  the  cold  striker  between  them ;  their  edges  are  carefully 
rounded  with  a  file  so  as  not  to  cut  the  work,  and  lastly  they  are 
hardened,  under  a  stream  of  water. 

In  preparing  the  work  for  the  collar  tools,  when  the  projection 
is  inconsiderable,  the  work  is  always  drawn  down  rudely  to  the 
form  between  the  top  and  bottom  fullers,  as  in  Fig.  48 ;  but  for 
greater  economy,  large  works  in  iron  are  sometimes  made  by  fold- 
ing a  ring  around  them  as  in  Fig.  56.  The  metal  for  a  large  ring 
is  occasionally  moulded  in  a  bottom  tool,  like  Fig.  99,  and  coiled 
up  to  the  shape  of  Fig.  100,  after  which  it  is  closed  upon  the  central 
rod  between  the  swages,  and  then  welded  within  them.  The  tools 
are  slightly  greased,  to  prevent  the  work  from  hanging  to  them, 
and  from  the  same  motive  their  surfaces  are  not  made  quite  flat  or 
perpendicular,  but  slightly  conical,  and  all  the  angles  are  obliterated 
and  rounded. 

The  spring  swage  tool,  represented  in  Fig.  101,  is  used  for  some 
small  manufacturing  purposes ;  it  differs  in  no  respect  from  the 
former,  except  in  the  steel  spring  which  connects  the  two  parts ;  it 
is  employed  for  light  single  hand-forgings.  Other  workmen  use 
swage  tools,  such  as  Fig.  102,  in  which  there  is  a  square  recess  in 
the  bottom  tool  to  fit  the  margin  of  the  top-tool  so  as  to  guide  it 
exactly  to  its  true  position.  In  practice  the  recess  in  the  bottom 
tool  would  be  deeper,  and  taper  or  larger  above  to  guide  the  tool 
more  easily  to  its  place  ;  but  if  so  drawn  the  figure  would  have 
been  less  distinct.  This  kind  also  may  be  used  for  single  hand 
works,  and  is  particularly  suited  to  those  which  are  of  rectangular 
section,  as  the  shoulders  of  table-knives;  these  do  not  admit  of 
being  twisted  round,  which  movement  furnishes  the  guide  for  the 
position  of  the  top-tool  in  forging  circular  works. 


GENERAL   EXAMPLES   OF   WELDING. 


143 


The  smith  has  likewise  a  variety  of  punches  of  all  shapes  and 
sizes,  for  making  holes  of  corresponding  forms ;  and  also  drifts  or 
mandrels,  used  alone  for  finishing  them,  many  of  which,  like  the 
turned  cones,  are  made  from  a  small  to  a  large  size  to  serve  for 
objects  of  various  sizes.  Two  examples  of  the  very  dexterous  use 
of  punches,  are  in  the  hands  of  almost  every  person,  namely  ordi- 
nary scissors  and  pliers. 

The  first  are  made  from  a  small  bar  of  flat  steel ;  the  end  is  flat- 


Figs.  104 


105 


tened  and  punched  with  a  small  round  hole,  which  is  gradually 
opened  upon  a  beak-iron,  Fig.  103,  attached  to  the  square  hole  of  the 
anvil ;  the  beak-iron  has  a  shallow  groove  (accidentally  omitted) 
for  rounding  the  inside  of  the  bows.  The  remaining  parts  of  the 
scissors  are  moulded  jointly  by  the  hammer,  and  bottom  swage 
tools ;  but  the  bows  are  mostly  finished  by  the  eye  alone. 

In  some  pliers,  the  central  half  of  the  joint  is  first  made ;  the 
aperture  in  the  other  part  is  then  punched  through  sideways,  and 


Figs.  106 


107 


I ~J 


sufficiently  bulged  out  to  allow  the  middle  joint  to  be  passed 
through,  after  which  the  outsides  are  closed  upon  the  centre.  This 
proceeding  exhibits,  in  the  smallest  kinds  especially,  a  surprising 
degree  of  dexterity  and  dispatch,  only  to  be  arrive  1  at  by  very 
great  practice;  and  which  in  this  and  numerous  other  instances  of 
manufacture  could  be  scarcely  attained  but  for  the  enormous  de- 


144  THE    PRACTICAL    METAL-WOBKEll'S   ASSISTANT. 

mand,  which  enables  a  great  subdivision  of  labor  to  be  success- 
fully applied  to  their  production. 

IVs  104  105,  106  and  107  represent  the  ordinary  trip  and  tilt 
hammer  used  in  this  country.  The  drawings  are  taken  from  those 
manufactured  at  the  Lowell  Machine  Shop,  Lowell,  Mass  of  which 
W  A  Burke  is  the  superintendent.  The  smaller  trip-hammers 
are  mounted  with  iron  bed-pieces  firmly  bolted  on  large  timber, 
furnished  with  a  cast-iron  stake,  adapted  to  drawing  and  swaging 
spindles,  bolts,  and  other  small  work,  balance  wheels  on  cam-shaft 
and  a  husk  adjustable  by  bolts  and  screws;  the  hammer-head 
weighing  from  thirty  to  one  hundred  and  twenty-five  pounds, 
driven  by  a  belt.  The  heavy  trip-hammer,  manufactured  in  this 
shop,  has  a  very  heavy  strong  cast-iron  frame,  adjustable  husk, 
cast-iron  stake,  driven  by  belt  with  balance-wheel  on  cam-shaft, 
and  suited  to  a  hammer-head  weighing  from  one  hundred  and 
twenty-five  to  four  hundred  pounds. 


CHAPTER  IX. 

HARDENING  AND   TEMPERING. 

GENERAL  VIEW  OF  THE  SUBJECT.— When  the  malleable  metals 
are  hammered  or  rolled,  they  generally  increase  in  hardness,  in 
elasticity,  and  in  density  or  specific  gravity;  which  effects  are  pro- 
duced simply  from  the  closer  approximation  of  their  particles,  and 
in  this  respect  steel  may  be  perhaps  considered  to  excel,  as  the 
process  called  hammer-hardening,  which  simply  means  hammer- 
ing without  heat,  is  frequently  employed  as  the  sole  means  of  har- 
dening some  kinds  of  steel  springs,  and  for  which  it  answers  re- 
markably well. 

After  a  certain  degree  of  compression,  the  malleable  metals 
assume  their  closest  and  most  condensed  states ;  and  it  then  be- 
comes necessary  to  discontinue  the  compression  or  elongation,  as 
it  would  cause  the  disunion  or  cracking  of  the  sheet  or  wire,  or 
else  the  metal  must  be  softened  by  the  process  of  annealing. 

The  metals,  lead,  tin,  and  zinc,  are  by  some  considered  to  be 
perceptibly  softened  by  immersion  in  boiling  water :  but  such  of 
the  metals  as  will  bear  it  are  generally  heated  to  redness,  the  co- 
hesion of  the  mass  is  for  the  time  reduced,  and  the  metal  becomes 
as  soft  as  at  first,  and  the  working  and  annealing  may  be  thus 
alternately  pursued,  until  the  sheet  metal,  or  the  wire,  reaches  its 
limit  of  tenuity. 

The  generality  of  the  metals  and  alloys  suffer  no  very  observ- 
able change,  whether  or  not  they  are  suddenly  quenched  in  water 


HARDENING  AND    TEMPERING.  145 

from  the  red  heat.  Pure  hammered  iron,  like  the  rest,  appears 
after  annealing,  to  be  equally  soft  whether  suddenly  or  slowly 
cooled ;  some  of  the  impure  kinds  of  malleable  iron  harden  by  im- 
mersion, but  only  to  an  extent  that  is  rather  hurtful  than  useful, 
and  which  may  be  considered  as  an  accidental  quality. 

Steel  however  receives  by  sudden  cooling  that  extreme  degree 
of  hardness  combined  with  tenacity,  which  places  it  so  incalculably 
beyond  every  other  material  for  the  manufacture  of  cutting  tools;, 
especially  as  it  likewise  admits  of  a  regular  gradation  from  extreme 
hajdness  to  its  softest  state,  when  subsequently  re-heated  or  tempered. 
Steel  therefore  assumes  a  place  in  the  economy  of  manufacture  un- 
approachable by  any  other  material:  consequently  we  may  safely 
say  that  without  it,  it  would  be  impossible  to  produce  nearly  all 
our  finished  works  in  metal  and  other  hard  substances;  for  although 
some  of  the  metallic  alloys  are  remarkable  for  hardness,  and  were 
used  for  various  implements  of  peaceful  industry,  and  also  those  of 
war,  before  the  invention  of  steel,  yet  in  point  of  absolute  and 
enduring  hardness,  and  equally  so  in  respect  to  elasticity  and  ten- 
acity, they  fall  exceedingly  short  of  hardened  steel. 

Hammer  hardening  renders  the  steel  more  fibrous  and  less  crys- 
talline, and  reduces  it  in  bulk;  on  the  other  hand,  fire  hardening 
makes  steel  more  crystalline,  and  frequently  of  greater  bulk ;  but 
the  elastic  nature  of  hammer  hardened  steel  will  not  take  so  wide 
nor  so  efficient  a  range  as  that  which  is  fire  hardened. 

If  we  attempt  to  seek  the  remarkable  difference  between  pure 
iron  and  steel  in  their  chemical  analyses,  it  appears  to  result  from 
a  minute  portion  of  carbon;  and  cast-iron,  which  possesses  a  much 
larger  share,  presents,  as  we  should  expect,  somewhat,  similar 
phenomena.  • 

Iron  semi-steelified contains  one  150th  of  carbon. 

Soft  cast-steel  capable  of  welding 
Cast-steel  for  common  purposes 


Cast-steel  requiring  more  hardness        .         .     . 
Steel  capable  of  standing  a  few  blows,  but  quite  ) 

unfit  for  drawing ) 

First  approach  to  a  steely  granulated  fracture 

White  cast-iron      . 

Mottled  cast-iron 

Carbonated  cast-iron 

Super-carbonated  crude  iron     .... 


120th          " 
100th          " 
90th 

50th          *' 

30th  to  40th. 

25th 

20th 

15  th          " 

12th 


For  the  mode  of  analysis  for  ascertaining  the  quantity  of  carbon 
in  cast-iron  and  steel,  invented  by  M.  V.  Regnault,  Mining  Engi- 
neer, see  Annales  de  Ckimie  et  de  Physique,  for  January,  1839;  also 
Journal  of  the  Franklin  Institute,  vol.  xxv.  p.  327.  It  is  stated 
that  the  analysis  is  very  easy  and  exact,  and  may  be  completed  in 
half  an  hour. 

Moreover,  as  the  hard  and  soft  conditions  of  »teel  may  be  re- 
versed backwards  and  forwards  without  any  rapid  chemical  change 
in  its  substance,  it  has  been  pronounced  to  result  from  internal 
10 


146  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

arrangement  or  crystallization,  which  may  be  in  a  degree  illustrated 
and  explained  by  similar  changes  observed  in  glass. 

A  wine-glass,  or  other  object  recently  blown,  and  plunged  whilst 
red  hot  into  cold  water,  cracks  in  a  thousand  places,  and  even 
cooled  in  warm  air  it  is  very  brittle,  and  will  scarcely  endure  the 
slightest  violence  or  sudden  change  of  temperature ;  and  visitors 
to  the  glass-house  are  often  shown  that  a  wine-glass,  or  other  article 
of,  irregular  form,  breaks  in  cooling  in  the  open  air  from  its  un- 
equal contraction  at  different  parts.  But  the  objects  would  have 
become  useful,  and  less  disposed  to  fracture,  if  they  had  been 
allowed  to  arrange  their  particles  gradually  during  their  very  slow 
passage  through  the  long  annealing  oven  or  leer  of  the  glass-house, 
the  end  at  which  they  enter  being  at  the  red  heat,  and  the  opposite 
extremity  almost  cold. 

To  perfect  the  annealing,  it  is  not  unusual  with  lamp-glasses, 
tubes  for  steam-gages,  and  similar  pieces  exposed  to  sudden  transi- 
tions of  heat  and  cold,  to  place  them  in  a  vessel  of  cold  water, 
which  is  slowly  raised  to  the  boiling  temperature,  kept  for  some 
hours  at  that  heat  and  then  allowed  to  cool  very  slowly :  the  effect 
thus  produced  is  far  from  chimerical.  For  such  pieces  of  flint 
glass  intended  for  cutting,  as  are  found  to  be  insufficiently  an- 
nealed, the  boiling  is  sometimes  preferred  to  a  second  passage 
through  the  leer :  lamp-glasses  are  also  much  less  exposed  to  frac- 
ture when  they  have  been  once  used,  as  the  heat,  if  not  too  sud- 
denly applied  or  checked,  completes  the  annealing. 

Steel  in  like  manner  when  suddenly  cooled  is  disposed  to  crack 
in  pieces,  which  is  a  constant  source  of  anxiety ;  the  danger  in- 
creases with  the  thickness  in  the  same  way  as  with  glass,  and  the 
more  especially  when  the  works  are  unequally  thick  and  thin. 

Another  ground  of  analogy  between  glass  and  steel  appears  to 
exist  in  the  pieces  of  unannealed  glass  used  for  exhibiting  the  phe- 
nomena formerly  called  double  refraction,  but  now  polarization 
of  light;  an  effect  distinctly  traced  to  its  peculiar  crystalline 
structure. 

In  glass  it  is  supposed  to  arise  from  the  cooling  of  the  external 
crust  more  rapidly  than  the  internal  mass  ;  the  outer  crust  is  there- 
fore in  a  state  of  tension,  or  restraint,  from  an  attempt  to  squeeze 
the  inner  mass  into  a  smaller  space  than  it  seems  to  require ;  and 
from  the  hasty  arrangement  of  the  unannealed  glass  the  natural 
positions  of  its  crystals  are  in  a  measure  disturbed  or  dislocated. 
It  has  been  shown  experimentally,  that  a  re-arrangement  of  the 
particles  of  glass  occurs  in  the  process  of  annealing,  as,  of  two 
pieces  of  the  same  tube  each  40  inches  long,  the  one  sent  through 
the  leer  contracted  one-sixteenth  of  an  inch  more  than  the  other, 
which  was  cooled  as  usual  in  the  open  air.  Tubes  for  philosophi- 
cal purposes  are  not  annealed,  as  their  inner  surfaces  are  apt  to 
become  soiled  w4th  the  sulphur  of  the  fuel ;  they  are  in  conse- 
quence very  brittle  and  liable  to  accident. 

The  unannealed  glass,  when  cautiously  heated  and  slowly  cooled, 


HARDENING   AND   TEMPERING.  147 

ceases  to  present  the  polarizing  effect,  and  the  steel  similarly 
treated  ceases  to  be  hard ;  and  may  we  not  therefore  indulge  in  the 
speculation,  that  in  both  cases  a  peculiar  crystalline  structure  is 
consequent  upon  the  unannealed  or  hardened  state  ? 

In  the  process  of  hardening  steel,  water  is  by  no  means  essen- 
tial, as  the  sole  object  is  to  extract  its  heat  rapidly,  and  the  follow- 
ing are  examples,  commencing  with  the  condition  of  extreme, 
hardness,  and  ending  with  the  reverse  condition. 

,  A  thin  heated 'blade  placed  between  the  cold  hammer  and  anvil, 
or  other  good  conductors  of  heat,  becomes  perfectly  hard.  Thicker 
pieces  of  steel,  cooled  by  exposure  to  the  air  upon  the  anvil,  be- 
come rather  hard,  but  readily  admit  of  being  filed.  They  become 
softer  when  placed  on  cold  cinders,  or  other  bad  conductors  of 
heat.  Still  more  .soft  when  placed  in  hot  cinders,  or  within  the 
fire  itself,  and  cooled  by  their  gradual  extinction.  When  the  steel 
is  encased  in  close  boxes  with  charcoal  powder,  and  it  is  raised  to 
a  red-heat  and  allowed  to  cool  in  the  fire  or  furnace,  it  assumes  its 
softest  state  ;  unless,  lastly,  we  proceed  to  its  partial  decomposition. 
This  is  done  by  enclosing  the  steel  with  iron  turnings  or  filings, 
the  scales  from  the  smith's  anvil,  lime,  or  other  matters  that  will 
abstract  the  carbon  from  its  surface ;  by  this  mode  it  is  super- 
ficially decarbonized,  or  reduced  to  the  condition  of  pure  soft  iron, 
in  the  manner  practised  by  Mr.  Jacob  Perkins,  of  Massachusetts, 
in  his  most  ingenious  and  effective  combination  of  processes, 
employed  for  producing  in  unlimited  numbers  absolutely  identi- 
cal impressions  of  bank  notes  and  checks,  for  the  prevention  of 
forgery.  These  methods  of  treating  steel  will  be  hereafter  noticed. 

A  nearly  similar  variety  of  conditions  might  be  referred  to  as 
existing  in  cast-iron  in  its  ordinary  state,  governed  by  the  magni- 
tude, quality,  and  management  of  the  castings ;  independently  of 
which,  by  one  particular  method,  some  cast-iron  may  be  rendered 
^externally  as  hard  as  the  hardest  steel ;  such  are  called  chilled  iron 
castings ;  and,  as  the  opposite  extreme,  by  a  method  of  annealing 
combined  with  partial  decomposition,  malleable  iron  castings  may 
be  obtained,  so  that  cast-iron  nails  may  be  clenched. 

Again,  the  purest  iron,  and  most  varieties  of  cast-iron,  may,  by 
another  proceeding,  be  superficially  converted  into  steel,  and  then 
hardened,  the  operation  being  appropriately  named  case-hardeniny. 
I  therefore  propose  to  illustrate  these  phenomena  collectively,  under 
three  divisions :  first,  the  hardening  and  tempering  of  steel ; 
secondly,  the  hardening  and  annealing  of  cast-iron ;  and  thirdly, 
the  process  of  case-hardening. 

PRACTICE  OF  HARDENING  AND  TEMPERING  STEEL. — It  may  per- 
haps be  truly  said,  that  upon  no  one  subject  connected  with  me- 
chanical art  docs  there  exist  such  a  contrariety  of  opinion,  not 
unmixed  with  prejudice,  as  upon  that  of  hardening  and  tempering 
steel ;  which  makes  it  often  difficult  to  reconcile  the  practices  fol- 
lowed by  different  individuals  in  order  to  arrive  at  exactly  similar 
ends.  The  real  difficulty  of  the  subject  occurs  in  part  from  the 


148  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

mysteriousness  of  the  change ;  and  from  the  absence  of  defined 
measures,  by  which  either  the  steps  of  the  process  itself,  or  the 
value  of  the  results  when  obtained,  may  be  satisfactorily  measured ; 
us  each  is  determined  almost  alone  by  the  unassisted  senses  of 
sight  and  touch,  instead  of  by  those  physical  means  by  which 
numerous  other  matters  may  be  strictly  tested  and  measured, 
nearly  without  reference  to  the  judgment  of  the  individual,  which 
in  its  very  nature  is  less  to  be  relied  upon. 

The  excellence  of  cutting-tools,  for  instance,  is  pronounced  upon 
their  relative  degrees  of  endurance,  but  many  accidental  circum- 
stances here  interfere  to  vitiate  the  strict  comparison :  and  in  respect 
to  the  measure  of  simple  hardness,  nearly  the  only  test  is  the  resist- 
ance the  objects  offer  to  the  file,  a  mode  in  two.  ways  defective,  as 
the  files  differ  amongst  themselves  in  hardness ;  and  they  only  serve 
to  indicate  in  an  imperfect  manner  to  the  touch  of  the  individual,  a 
general  notion  without  any  distinct  measure,  so  that  when  the  opinion 
of  half  a  dozen  persons  may  be  taken,  upon  as  many  pieces  of  steel 
differing  but  slightly  in  hardness,  the  want  of  uniformity  in  their 
decisions  will  show  the  vague  nature  of  the  proof. 

Under  these  circumstances,  instead  of  recommending  any  partic- 
ular methods,  I  have  determined  to  advance  a  variety  of  practical 
examples  derived  from  various  sources,  which  will  serve  in  most 
cases  to  confirm,  but  in  some  to  confute  one  another ;  leaving  to 
every  individual  to  follow  those  examples  which  may  be  the  most 
nearly  parallel  with  his  own  wants.  There  are,  however,  some  few 
points  upon  which  it  may  be  said  that  all  are  agreed ;  namely, 

The  temperature  suitable  to  forging  and  hardening  steel  differs 
in  some  degree  with  its  quality  and  its  mode  of  manufacture ;  the 
heat  that  is  required  diminishes  with  the  increase  of  carbon : 

In  every  case  the  lowest  available  temperature  should  be  employed 
in  each  process,  the  hammering  should  be  applied  in  the  most  equal 
manner  throughout,  and  for  cutting  tools  it  should  be  continued  until 
they  are  nearly  cold : 

Coke  or  charcoal  is  much  better  as  a  fuel  than  fresh  coal,  the 
sulphur  of  which  is  highly  injurious : 

The  scale  should  be  removed  from  the  face  of  the  work  to  expose 
it  the  more  uniformly  to  the  effect  of  the  cooling  medium : 

Hardening  a  second  time  without  the  intervention  of  hammering 
is  attended  with  increased  risk ;  and  the  less  frequently  steel  passes 
through  the  fire  the  better. 

In  hardening  and  tempering  steel  there  are  three  things  to  be 
considered ;  namely,  the  means  of  heating  the  objects  to  redness, 
the  means  of  cooling  the  same,  and  the  means  of  applying  the  heat 
for  tempering  or  letting  them  down.  I  will  speak  of  these  sepa- 
rately, before  giving  examples  of  their  application. 

The  smallest  works  are  heated  with  the  flame  of  the  blowpipe, 
and  are  occasionally  supported  upon  charcoal ;  but  as  the  blowpipe 
is  used  to  a  far  greater  extent  in  soldering,  its  management  will  be 
described  in  the  chapter  devoted  to  that  process. 


HARDENING   AND   TEMPERING.  149 

For  objects  that  are  too  large  to  be  heated  by  the  blowpipe,  and 
too  small  to  be  conveniently  warmed  in  the  naked  fire,  various  pro- 
tective means  are  employed.  Thus,  an  iron  tube  or  sheet-iron  box 
inserted  in  the  midst  of  the  ignited  fuel  is  a  safe  and  cleanly  way  ; 
it  resembles  the  muffle  employed  in  chemical  works.  The  work  is 
then  managed  with  long  forceps  made  of  steel  or  iron  wire,  bent  in 
the  form  of  the  letter  U,  and  flattened  or  hollowed  at  the  ends.  A 
crucible  or  an  iron  pot  about  four  to  six  inches  deep,  filled  with 
lead  and  heated  to  redness,  is  likewise  excellent,  but  more  particu- 
larly for  long  and  thin  tools,  such  as  gravers  for  artists,  and  other 
slight  instruments ;  several  of  these  may  be  inserted  at  once, 
although  towards  the  last  they  should  be  moved  about  to  equalize 
the  heat ;  the  weight  of  the  lead  makes  it  desirable  to  use  a  bridle 
or  trevet  for  the  support  of  the  crucible.  Some  workmen  place  on 
the  fire  a  pan  of  charcoal  dust,  and  heat  it  to  redness. 

Great  numbers  of  tools,  both  of  medium  and  large  size,  are  heated 
in  the  ordinary  forge  fire,  which  should  consist  of  cinders  rather 
than  fresh  coals ;  coke  and  also  charcoal  are  used,  but  far  less  gen- 
erally ;  recourse  is  also  had  to  hollow  fires,  the  construction  of 
which  was  explained  at  page  94  ;  but  the  bellows  should  be  very 
sparingly  used,  except  in  blowing  up  the  fire  before  the  introduc- 
tion of  the  work,  which  should  be  allowed  ample  time  to  get  hot,  or, 
as  if!  is  called,  to  " soak" 

Which  method  soever  may  be  resorted  to  for  heating  the  work, 
the  greatest  care  should  be  given  to  communicate  to  all  the  parts 
requiring  to  be  hardened  a  uniform  temperature,  and  which  is  only 
to  be  arrived  at  by  cautiously  moving  the  work  to  and  fro  to  expose 
all  parts  alike  to  the  fire ;  the  difficulty  of  accomplishing  this  of 
course  increases  with  long  objects,  for  which  fires  of  proportionate 
length  are  required. 

It  is  far  better  to  err  on  the  side  of  deficiency  than  of  excess  of 
heat ;  the  point  is  rather  critical,  and  not  alike  in  all  varieties  of 
steel.  Until  the  quality  of  the  steel  is  familiarly  known,  it  is  a  safe 
precaution  to  commence  rather  too  low  than  otherwise,  as  then  the 
extent  of  the  mischief  will  be  the  necessity  for  a  repetition  of  the 
process  at  a  higher  degree  of  heat;  but  the  steel,  if  burned  or 
over-heated,  will  be  covered  with  scales,  and  what  is  far  worse,  its 
quality  will  be  permanently  injured;  a  good  hammering  will,  in 
a  degree,  restore  it ;  but  this  in  finished  works  is  generally  imprac- 
ticable. 

Less  than  a  certain  heat  fails  to  produce  hardness,  and  in  the 
opinion  of  some  workmen  has  quite  the  opposite  eftect,  and  they 
consequently  resort  to  it  as  the  means  of  rapid  annealing ;  not, 
however,  by  plunging  the  steel  into  the  water  and  allowing  it  to 
remain  until  cold,  but  dipping  it  quickly,  holding  it  in  the  steam 
for  a  few  moments,  dipping  it  again  and  so  on,  reducing  it  to  the 
cold  state  in  a  hasty  but  intermittent  manner. 

There  is  another  opinion  prevalent  amongst  workmen,  that  steel 
which  is  " pinny"  or  as  if  composed  of  a  bundle  of  hard  wijes,  is 


150  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

rendered  uniform  in  its  substance  if  it  is  first  hardened  and  then 
annealed. 

Secondly,  the  choice  of  the  cooling  medium  has  reference  mainly 
to  the  relative  powers  of  conducting  heat  they  severally  possess : 
the  following  have  been  at  different  times  resorted  to  with  various 
degrees  of  success :  currents  of  cold  air ;  immersion  in  water  in 
various  states,  in  oil  or  wax,  and  in  freezing  mixtures ;  mercury, 
and  flat  metallic  surfaces  have  been  also  used.  Plain  water,  at  a 
temperature  of  40°  Fahrenheit,  has  been  recommended.  On  the 
whole,  however,  there  appears  to  be  an  opinion  that  mercury  gives 
the  greatest  degree  of  hardness ;  then  cold  salt  and  water,  or  water 
mixed  Avith  various  "  astringent  and  acidifying  matters ;"  plain 
water  follows ;  and  lastly,  oily  mixtures. 

I  find  but  one  person  who  has  commonly  used  the  mercury. 
Many  presume  upon  the  good  conducting  power  of  the  metal, 
and  the  non-formation  of  steam,  which  causes  a  separation  betwixt 
the  steel  and  water,  when  the  latter  is  employed  as  the  cooling  me- 
dium. I  have  failed  to  learn  the  reason  of  the  advantage  of  salt 
and  water,  unless  the  fluid  have,  as  well  as  a  greater  density,  a 
superior  conducting  power.  The  file-makers  medicate  the  water 
in  other  ways,  but  this  is  one  of  the  questionable  mysteries  which 
is  never  divulged, — although  it  is  supposed  that  a  small  quantity 
of  white  arsenic  is  generally  added  to  water  saturated  with  »salt. 
One  thing,  however,  may  be  noticed,  that  articles  hardened  in  salt 
and  water  are  apt  to  rust,  unless  they  are  laid  for  a  time  in  lime- 
water,  or  some  neutralizing  agent. 

With  plain  water,  an  opinion  very  largely  exists  in  favor  of  that 
which  has  been  used  over  and  over  again,  even  for  years,  provided 
it  is  not  greasy :  and  when  the  steel  is  very  harsh,  the  chill  is 
taken  off  plain  water  to  lessen  the  risk  of  cracking  it.  Oily  mix- 
tures impart  to  thin  articles,  such  as  springs,  a  sufficient  and  milder 
degree  of  hardness,  with  less  danger  of  cracking,  than  from  water ; 
and  in  some  cases  a  medium  course  is  pursued  by  covering  the 
water  with  a  thick  film  of  oil,  which  is  said  to  be  adopted  occa- 
sionally with  scythes,  reaping-hooks,  and  thin  edge-tools. 

A  so-called  natural  spring  is  made  by  a  vessel  with  a  true  and  a 
false-bottom,  the  latter  perforated  with  small  holes  ;  it  is  filled  with 
water,  and  a  copious  supply  is  admitted  beneath  the  partition  ;  it 
ascends  through  the  holes,  and  pursues  the  same  current  as  the 
heated  portions,  which  ajso  -escape  at  the  top.  This  was  invented 
by  the  late  John  Oldham,  of  Dublin,  Engineer  to  the  Bank  of 
England,  and  was  used  by  him  in  hardening  the  rollers  for  trans- 
ferring the  impressions  to  the  steel -plates  for  bank-notes. 

Sometimes  when  neighboring  parts  of  works  are  required  to  be 
respectively  hard  and  soft,  metal  tubes  or  collars  are  fitted  tight 
upon  the  work,  to  protect  the  parts  to  be  kept  soft  from  the  direct 
action  of  the  water,  at  any  rate  for  so  long  a  period  as  they  retain 
the  temperature  suitable  to  hardening. 

The  process  of  hardening  is  generally  one  of  anxiety,  as  the 


HARDENING   AND  TEMPERING.  151 

sudden  transition  from  heat  to  cold  often  causes  the  works  to  be- 
come greatly  distorted  if  not  cracked.  The  last  accident  is  much 
the  most  likely  to  occur  with  thick  massive  pieces,  which  are,  as  it 
were,  hardened  in  layers, — as  although  the  external  crust  or  shell 
may  be  perfectly  hard,  there  is  almost  a  certainty  that  towards  the 
centre  the  parts  are  gradually  less  hard ;  and  when  broken,  the 
inner  portions  will  sometimes  admit  of  being  readily  filed. 

When  in  the  fire  the  steel  becomes  altogether  expanded,  and  in 
the  water  its  outer  crust  is  suddenly  arrested,  but  with  a  tendency 
to  contract  from  the  loss  of  heat,  which  cannot  so  rapidly  occur  at 
the  central  part ;  it  may  be  therefore  presumed  that  the  inner  bulk 
continues  to  contract  after  the  outer  'crust  is  fixed,  and  which  tends 
to  tear  the  two  asunder,  the  more  especially  if  there  be  any  de- 
fective part  in  the  steel  itself.  An  external  flake  of  greater  or 
less  extent  not  unfrequently  shells  off  in  hardening  ;  and  it  often 
happens  that  works  remain  unbroken  for  hours  after  removal  from 
the  water,  but  eventually  give  way  and  crack  with  a  loud  report, 
from  the  rigid  unequal  tension  produced  by  the  violence  of  the 
process  of  hardening. 

The  contiguity  of  thick  and  thin  parts  is  also  highly  dangerous, 
as  they  can  neither  receive  nor  yield  up  heat  in  the  same  times. 
The  mischief  is  sometimes  lessened  by  binding  pieces  of  metal 
around  the  thin  parts  with  wire,  to  save  them  from  the  action  of 
the  cooling  medium.  Sharp  angular  notches  are  also  fertile  sources 
of  mischief,  and  where  practicable  they  should  be  rejected  in  favor 
of  curved  lines. 

As  regards  both  cracks  and  distortions,  it  may  perhaps  be 
generally  said  that  their  avoidance  depends  principally  upon  ma- 
nipulation, or  the  successful  management  of  every  step :  first,  the 
original  manufacture  of  the  steel,  its  being  forged  and  wrought  so 
that  it  may  be  equally  condensed  on  all  sides  with  the  hammer, 
otherwise  when  the  cohesion  of  the  mass  is  lessened  from  its  be- 
coming red  hot,  it  recovers  in  part  from  any  unequal  state  of  den- 
sity in  which  it  may  have  been  placed. 

Whilst  red  hot  it  is  also  in  its  weakest  condition.  It  is  there- 
fore prone  to  injury,  either  from  incautious  handling  with  the 
tongs,  or  from  meeting  the  sudden  cooling  action  irregularly,  and 
therefore  it  is  generally  best  to  plunge  works  vertically,  as  all  parts 
are  then  exposed  to  equal  circumstances,  and  less  disturbance  is 
risked  than  when  the  objects  are  immersed  obliquely  or  sideways 
into  the  water, — although  for  swords,  and  objects  of  similar  form, 
it  is  found  the  best  to  dip  them  exactly  as  in  making  a  vertical 
downward  cut  with  a  sabre,  which  for  this  weapon  is  its  strongest 
direction. 

Occasionally  objects  are  clamped  between  stubborn  pieces  of 
metal,  as  soft  iron  or  copper,  during  their  passage  through  the  fire 
and  water.  Such  plans  can  be  seldom  adopted,  and  are  rarely  fol- 
lowed, the  success  of  the  process  being  mostly  allowed  to  depend 
exclusively  upon  good  general  management. 


152 


THE   PRACTICAL   MF:TAL- WORKER'S   ASSISTANT. 


In  making  the  magnets  for  needles  ten  inches  long,  one-fourth 
of  an  inch  wtde,  and  the  two-hundredth  part  of  an  inch  thick,  this 
precaution  entirely  failed;  and  the  needles  assumed  all  sorts  ^  of 
distortions  when  released  from  between  the  stiff  bars  within  which 
they  were  hardened.  The  plan  was  eventually  abandoned  and  the 
magnets  were  heated  in  the  ordinary  way  within  an  iron  tube,  and 
were  set  straight  with  the  hammer  after  being  let  down  to  a 
deep  orange  or  brown  color.  Steel,  however,  is  in  the  best  con- 
dition for  the  formation  of  good  permanent  magnets  when  per- 
fectly hard. 

In  all  cases  the  thick  unequal  scale  left  from  the  forge  should  be 
ground  off  before  hardening,  in  order  to  expose  a  clean  metallic 
surface,  otherwise  the  cooling  medium  cannot  produce  its  due  and 
equal  effect  throughout  the  instrument.  The  edges  also  should  be 
left  thick,  that  they  may  not  be  burned  in  the  fire ;  thus  it  will 
frequently  happen  that  the  extreme  end  or  edge  of  a  tool  is  in- 
ferior in  quality  to  the  part  within,  and  that  the  instrument  is 
much  better  after  it  has  been  a  few  times  ground. 

Thirdly,  the  heat  for  tempering  or  letting  down.  Between  the 
extreme  conditions  of  hard  and  soft  steel  there  are  many  interme- 
diate grades,  the  common  index  for  which  is  the  oxidation  of  the 
brightened  surface,  and  it  is  quite  sufficient  for  practice.  These  tints, 
and  their  respective  approximate  temperatures,  are  thus  tabulated : 


Tools  for  metals. 

Tools  for  wood,  and  screw 

taps,  etc. 
Hatchets,  chipping  chisels, 

and     other    percussive 

tools,  saws,  etc. 

•  Springs. 

^  Too  soft  for  the  above  pur- 
[     poses. 


The  first  tint  arrives  at  about  430°  F.,  but  it  is  only  seen  by 
comparison  with  a  piece  of  steel  not  heated :  the  tempering  colors 
differ  slightly  with  the  various  qualities  of  steel. 

The  heat  for  tempering  being  moderate,  it  is  often  supplied  by 
the  part  of  the  tool  not  requiring  to  be  hardened,  and  which  is 
not  therefore  cooled  in  the  water.  The  workman  first  hastily  tries 
with  a  file  whether  the  work  is  hard ;  he  then  partially  brightens 
it  at  a  few  parts  with  a  piece  of  grindstone  or  an  emery  stick,  that 
he  maybe  enabled  to  watch  for  the  required  color;  which  attained, 
the  work  is  usually  cooled  in  any  convenient  manner,  lest  the 
body  of  the  tool  should  continue  to  supply  heat.  But  when,  on  the 
contrary,  the  color  does  not  otherwise  appear,  partial  recurrence 
is  had  to  the  node  in  which  the  work  is  heated,  as  the  flame 
of  the  candle,  or  the  surface  of  the  clear  fire  applied,  if  possible,  a 


1.  Very  pale  straw  yellow 
2.  A  shade  of  darker  yellow 
3.  Darker  straw  yellow    . 
4.  Still  darker  straw  yellow 
5.  A  brown  yellow   . 
tj.  A  yellow,  tinged  slightly  wi 
7.  Light  purple 
8.  Dark  purple          .        . 
9.  Dark  blue     . 

430  de 
450   " 
470   " 
490   " 
500 
h  purple  520 
530 
550 
S7n 

10.  Paler  blue    .         .         .                           590 

11.  Still  paler  blue     ....         610 
12.  Still  paler  blue,  with  a  tinge  of  green   630 

HARDENING   AND   TEMPERING.  153 

little  below  the  part  where  the  color  is  to  be  observed,  that  it  may 
not  be  soiled  by  the  smoke. 

A  very  convenient  and  general  manner  of  tempering  small  ob- 
jects is  to  heat  to  redness  a  few  inches  of  the  end  of  a  flat  bar  of 
iron  about  two  feet  long ;  it  is  laid  across  the  anvil,  or  fixed  by  its 
cold  extremity  in  the  vice ;  and  the  work  is  placed  on  that  part  of 
its  surface  which  is  found  by  trial  to  be  of  the  suitable  tempera- 
ture, by  gradually  sliding  the  work  towards  the  heated  extremity. 
In  this  manner  many  tools  may  be  tempered  at  once,  those  at  the 
hot  part  being  pushed  off  into  a  vessel  of  water  or  oil,  as  they 
severally  show  the  required  color,  but  it  requires  dexterity  and 
quickness  in  thus  managing  many  pieces. 

Vessels  containing  oil  or  fusible  alloys  carefully  heated  to  the 
required  temperatures  have  also  been  used,  and  I  shall  have  to 
describe  a  method  called  "blazing-off"  resorted  to  for  many  articles, 
such  as  springs  and  saws,  by  heating  them  over  the  naked  fire  until 
the  oil,  wax,  or  composition  in  which  they  have  been  hardened 
ignites ;  this  can  only  occur  when  they  respectively  reach  their 
boiling  temperatures  and  are  also  evaporated  in  the  gaseous  form. 

The  period  of  letting  down  the  works  is  also  commonly  chosen 
for  correcting,  by  means  of  the  hammer,  those  distortions  which  so 
commonly  occur  in  hardening ;  this  is  done  upon  the  anvil,  either 
with  the  thin  pane  of  an  ordinary  hammer,  or  else  with  a  hack- 
hammer, a  tool  terminating  at  each  end  in  an  obtuse  chisel  edge 
which  requires  continual  repair  on  the  grindstone. 

The  blows  are  given  on  the  hollow  side  of  the  work,  and  at  right 
angles  to  the  length  of  the  curve;  they  elongate  the  concave  side, 
and  gradually  restore  it  to  a  plane  surface,  when  the  blows  are  dis- 
tributed consistently  with  the  position  of  the  erroneous  parts. 
The  hack-hammer  unavoidably  injures  the  surface  of  the  work, 
but  the  blows  should  not  be  too  violent,  as  they  are  then  also  more 
prone  to  break  the  work,  the  liability  to  which  is  materially 
lessened  when  it  is  kept  at  or  near  the  tempering  heat,  and  the 
edge  of  the  hack-hammer  is  slightly  rounded. 

COMMON  EXAMPLES  OF  HARDENING  AND  TEMPERING  STEEL.— 
Watchmakers'  drills  of  the  smallest  kinds  are  heated  in  the  blue 
part  of  the  flame  of  the  candle ;  larger  drills  are  heated  with  the 
blowpipe  flame,  applied  very  obliquely,  and  a  little  below  the 
point ;  when  very  thin  they  may  be  whisked  in  the  air  to  cool 
them,  but  they  are  more  generally  thrust  into  the  tallow  of  the 
candle  or  the  oil  of  a  lamp  ;  they  are  tempered  either  by  their  own 
heat,  or  by  immersion  in  the  flame  below  the  point  of  the  tool. 

For  tools  between  those  suited  to  the  action  of  the  blowpipe 
and  those  proper  for  the  open  fire,  there  are  many  which  require 
either  the  iron  tube,  or  the  bath  of  lead  or  charcoal  described  at 
page  149,  but  the  greater  number  of  works  are  hardened  in  the 
ordinary  smith's  fire,  without  such  defences. 

Tools  of  moderate  size,  such  as  the  majority  of  turning  tools, 
carpenters'  chisels,  and  gouges,  and  so  forth,  are  generally  heated 


154  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

in  the  open  fire ;  they  require  to  be  continually  drawn  backwards 
and  forwards  through  the  lire,  to  equalize  the  temperature  applied, 
they  are  plunged  vertically  into  the  water,  and  then  moved  about; 
sideways  to  expose  them  to  the  cooler  portions  of  the  fluid.  If 
needful,  they  are  only  dipped  to  a  certain  depth,  the  remainder 
being  left  soft. 

Some  persons  use  a  shallow  vessel  filled  only  to  the  height  of 
the  portion  to  be  hardened,  and  plunge  the  tools  to  the  bottom ; 
but  this  strict  line  of  demarkation  is  sometimes  dangerous,  as  the 
tools  are  apt  to  become  cracked  at  the  part,  and  therefore  a  small 
vertical  movement  is  also  generally  given,  that  the  transition  from 
the  hard  to  the  soft  part  may  occupy  more  length. 

Razors  and  penknives  are  too  frequently  hardened  without  the 
removal  of  the  scale  arising  from  the  forging ;  this  practice,  which  is 
not  done  with  the  best  works,  cannot  be  too  much  deprecated.  The 
blades  are  heated  in  a  coke  or  charcoal  fire,  and  dipped  into  the 
water  obliquely.  In  tempering  razors,  they  are  laid  on  their 
backs  upon  a  clear  fire,  about  half-a-dozen  together,  and  they  are 
removed  one  at  a  time,  when  the  edges,  which  are  as  yet  thick, 
come  down  to  a  pale  straw  color.  Should  the  backs  accidentally 
get  heated  beyond  the  straw  color,  the  blades  are  cooled  in  water, 
but  not  otherwise.  Penknife  blades  are  tempered,  a  dozen  or  two 
at  a  time,  on  a  plate  of  iron  or  copper  about  twelve  inches  long, 
three  or  four  wide,  and  about  a  quarter  of  an  inch  thick ;  the  blades 
are  arranged  close  together  on  their  backs,  and  lean  at  an  angle 
against  each  other.  As  they  come  down  to  the  temper,  they  are 
picked  out  with  small  pliers  and  thrown  into  water  if  necessary ; 
other  blades  are  then  thrust  forward  from  the  cooler  parts  of  the 
plate  to  take  their  place. 

Hatchets,  adzes,  cold  chisels,  and  numbers  of  similar  tools,  in 
which  the  total  bulk  is  considerable  compared  with  the  part  to  be 
hardened,  are  only  partially  dipped ;  they  are  afterwards  let  clown 
by  the  heat  of  the  remainder  of  the  tool,  and  when  the  color  indic- 
ative of  the  temper  is  attained,  they  are  entirely  quenched.  With 
the  view  of  removing  the  loose  scales,  or  the  oxidation  acquired  in 
the  fire,  some  workmen  rub  the  objects  hastily  in  dry  salt  before 
plunging  them  in  the  water,  in  order  to  give  them  a  cleaner  and 
whiter  face. 

_  In  hardening  large  dies,  anvils,  and  other  pieces  of  considerable 
size,  by  direct  immersion,  the  rapid  formation  of  steam  at  the  sides 
of  the  metal  prevents  the  free  access  of  the  water  for  the  removal 
of  the  heat  with  the  required  expedition ;  in  these  cases,  a  copious 
stream  of  water  from  a  reservoir  above  is  allowed  to  fall  on  the 
surface  to  be  hardened.  This  contrivance  is  frequently  called  a 
"float,"  and  although  the  derivation  of  the  name  is  not  very  clear, 
the  practice  is  excellent,  as  it  supplies  an  abundance  of  cold  water  ; 
and  which,  as  it  falls  directly  on  the  centre  of  the  anvil,  is  sure  to 
render  that  part  hard.  It  is,  however,  rather  dangerous  to  stand 
near  such  works  at  the  time,  as  when  the  anvil  face  is  not  perfectly 


HARDENING   AND   TEMPERING.  155 

welded,  it  sometimes  in  part  flies  off  with  great  violence  and  a  loud 
report. 

Occasionally  the  object  is  partly  immersed  in  a  tank  beneath  the 
fall  of  water,  by  means  of  a  crane  and  slings ;  it  is  ultimately  tem- 
pered with  its  own  heat,  and  dropped  in  the  water  to  become  en- 
tirely cold. 

Oil,  or  various  mixtures  of  oil,  tallow,  wax,  and  resin,  are  used 
for  many  thin  and  elastic  objects,  such  as  needles,  fish-hooks,  steel 
pens  and  springs,  which  require  a  milder  degree  of  hardness  than 
is  given  by  water. 

For  example,  steel  pens  are  heated  in  large  quantities  in  iron 
trays  within  a  furnace,  and  are  then  hardened  in  an  oily  mixture ; 
generally  they  are  likewise  tempered  in  oil,  or  a  composition  the 
boiling  point  of  which  is  the  same  as  the  temperature  suited  to 
letting  them  down.  This  mode  is  particularly  expeditious,  as  the 
temper  cannot  fall  below  the  assigned  degree.  The  dry  heat  of  an 
oven  is  also  used,  and  both  the  oil  and  oven  may  be  made  to  serve 
for  tempers  harder  than  that  given  by  boiling  oil ;  but  more  care 
and  observation  are  required  for  these  lower  temperatures. 

Saws  and  springs  are  generally  hardened  in  various  composi- 
tions of  oil,  suet,  wax  and  other  ingredients,  which,  however,  lose 
their  hardening  property  after  a  few  weeks'  constant  use :  the  saws 
are  heated  in  long  furnaces,  and  then  immersed  horizontally  and 
edge- ways  in  a  long  trough  containing  the  composition;  two  troughs 
are  commonly  used,  the  one  until  it  gets  too  warm,  then  the  other 
for  a  period,  and  so  on  alternately.  Part  of  the  composition  is 
wiped  off  the  saws  with  a  piece  of  leather,  when  they  are  removed 
from  the  trough,  and  they  are  heated  one  by  one  over  a  clear  coke 
fife,  until  the  grease  inflames ;  this  is  called  "  blazing  off" 

The  composition  used  by  an  experienced  saw-maker  is  two 
pounds  of  suet  and  a  quarter  of  a  pound  of  bees- wax  to  every 
gallon  of  whale-oil ;  these  are  boiled  together,  and  will  serve  for 
thin  works  and  most  kinds  of  steel.  The  addition  of  black  resin, 
to  the  extent  of  about  one  pound  to  the  gallon,  makes  it  serve  for 
thicker  pieces  and  for  those  it  refused  to  harden  before ;  but  the 
resin  should  be  added  with  judgment,  or  the  works  will  become 
too  hard  and  brittle.  The  composition  is  useless  when  it  has  been 
constantly  employed  for  about  a  month ;  the  period  depends,  how- 
ever, on  the  extent  to  which  it  is  used,  and  the  trough  should  bo 
thoroughly  cleansed  out  before  new  mixture  is  placed  in  it. 

The  following  recipe  is  recommended : 

Twenty  gallons  of  spermaceti  oil ; 

Twenty  pounds  of  beef  suet  rendered ; 

One  gallon  of  neat's-foot  oil ; 

One  pound  of  pitch  ; 

Three  pounds  of  black  resin. 

These  last  two  articles  must  be  previously  melted  together,  and 
then  added  to  the  other  ingredients;  when  the  whole  must  be 
heated  in  a  proper  iron  vessel,  with  a  close  cover  fitted  to  it,  until 


156  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

the  moisture  is  entirely  evaporated,  and  the  composition  will  take 
fire  on  a  flaming  body  being  presented  to  its  surface,  but  which 
must  be  instantly  extinguished  again  by  putting  on  the  cover  of 
the  vessel. 

When  the  saws  are  wanted  to  be  rather  hard,  but  little  of  the 
grease  is  burned  off;  when  milder,  a  larger  portion ;  and  for  a 
spring  temper,  the  whole  is  allowed  to  burn  away.  When  the 
work  is  thick,  or  irregularly  thick  and  thin,  as  in  some  springs,  a 
second  and  third  dose  is  burned  off,  to  insure  equality  of  temper 
at  all  parts  alike. 

(run-lock  springs  are  sometimes  literally  fried  in  oil  for  a  con- 
siderable time  over  a  fire  in  an  iron  tray ;  the  thick  parts  are  then 
sure  to  be  sufficiently  reduced,  and  the  thin  parts  do  not  become 
the  more  softened  from  the  continuance  of  the  blazing  heat. 

Springs  and  saws  appear  to  lose  their  elasticity,  after  hardening 
and  tempering,  from  the  reduction  and  friction  they  undergo  in 
grinding  and  polishing.  Towards  the  conclusion  of  the  manufac- 
ture, the  elasticity  of  the  saw  is  restored  principally  by  hammer- 
ing, and  partly  by  heating  it  over  a  clear  coke  fire  to  a  straw 
color:  the  tint  is  removed  by  very  diluted  muriatic  acid,  after 
which  the  saws  are  well  washed  in  plain  water  and  dried. 

Watch  springs  are  hammered  out  of  round  steel  wire,  of  suitable 
diameter,  until  they  fill  the  gage  for  width,  which  at  the  same  time 
insures  equality  of  thickness;  the  holes  are  punched  in  their 
extremities,  and  they  are  trimmed  on  the  edge  with  a  smooth  file ; 
the  springs  are  then  tied  up  with  binding- wire,  in  a  loose  open 
coil,  and  heated  over  a  charcoal  fire  upon  a  perforated  revolving 
plate,  they  are  hardened  in  oil,  and  blazed  off. 

The  spring  is  now  distended  in  a  long  metal  frame,  similar  *  to 
that  used  for  a  saw  blade,  and  ground  and  polished  with  emery  and 
oil,  between  lead  blocks ;  by  this  time  its  elasticity  appears  quite 
lost,  and  it  may  be  bent  in  any  direction ;  its  elasticity  is,  how- 
ever, entirely  restored  by  a  subsequent  hammering  on  a  very  bright 
anvil,  which  "puts  tlie  nature  into  the  spring" 

The  coloring  is  done  over  a  flat  plate  of  iron,  or  hood,  under 
which  a  little  spirit-lamp  is  kept  burning ;  the  spring  is  continually 
drawn  backwards  and  forwards,  about  two  or  three  inches  at  a 
time,  until  it  assumes  the  orange  or  deep  blue  tint  throughout,  ac- 
cording to  the  taste  of  the  purchaser ;  by  many  the  coloring  is 
considered  to  be  a  matter  of  ornament,  and  not  essential.  The 
last  process  is  to  coil  the  spring  into  the  spiral  form,  that  it  may 
enter  the  barrel  in  which  it  is  to  be  contained ;  this  is  done  by  a 
tool  with  a  small  axis  and  winch  handle,  and  does  not  require  heat. 

The  balance-springs  of  marine  chronometers,  which  are  in  the 
form  of  a  screw,  are  wound  into  the  square  thread  of  a  screw  of 
the  appropriate  diameter  and  coarseness ;  the  two  ends  of  the 
spring  are  retained  by  side  screws,  and  the  whole  is  carefully  en- 
veloped in  platinum- foil,  and  tightly  bound  with  wire.  The  mass 
is  next  heated  in  a  piece  of  gun  barrel  closed  at  the  one  end,  and 


HARDENING   AND   TEMPERING.  157 

plunged  into  oil,  which  hardens  the  spring  almost  without  discol- 
oring it,  owing  to  the  exclusion  of  the  air  by  the  close  platinum 
covering,  which  is  now  removed,  and  the  spring  is  let  down  to  the 
blue,  before  removal  from  the  screwed  block. 

The  balance  or  hair-springs  of  common  watches  are  frequently 
left  soft ;  those  of  the  best  watches  are  hardened  in  the  coil  upon 
a  plain  cylinder,  and  are  then  curled  into  the  spiral  form  between 
the  edge  of  a  blunt -knife  and  the  thumb,  the  same  as  in  curling  up 
a  na*rrow  ribbon  of  paper,  or  the  filaments  of  an  ostrich  feather. 

Thirty-two  hundred  balance  springs  Weigh  about  an  ounce.  The 
soft  springs  are  worth  60  cents  each  ;  the  hardened  and  tempered 
springs,  $1.26  each.  This  raises  the  value  of  the  steel,  originally 
less  than  four  cents,  to  $2000  and  $8000  respectively.  But  springs 
also  include  the  heaviest  examples  of  hardened  steel  works  uncom- 
bined  with  iron :  for  example,  bow-springs  for  all  kind  of  vehicles, 
some  intended  for  railway  use,  measure  3J  feet  long,  and  weigh  50 
pounds  each  piece ;  two  of  these  are  used  in  combination  ;  other 
single  springs  are  6  feet  long,  and  weigh  seventy  pounds.  The 
principle  of  these  bow-springs  will  be  immediately  seen,  by  con- 
ceiving the  common  archery  bow  fixed  horizontally  with  its  cord 
upwards ;  the  body  of  the  carriage  being  attached  to  the  cord 
sways  both  perpendicularly  and  sideways  with  perfect  freedom. 

In  hardening  them  they  are  heated  by  being  drawn  backwards 
and  forwards  through  an  ordinary  forge  fire,  built  hollow,  and  they 
are  immersed  in  a  trough  of  plain  water :  in  tempering  them  they 
are  heated  until  the  black  red  is  just  visible  at  night;  by  daylight 
the  heat  is  denoted  by  its  making  a  piece  of  wood  sparkle  when 
rubbed  on  the  spring,  which  is  then  allowed  to  cool  in  the  air.  The 
metal  is  nine- sixteenths  of  an  inch  thick,  and  some  consider  five- 
eighths  the  limits  to  which  steel  will  harden  properly,  that  is  suffi- 
ciently alike  to  serve  as  a  spring ;  their  elasticity  is  tested  far 
beyond  their  intended  range. 

Great  diversity  of  opinion  exists  respecting  the  cause  of  elastic- 
ity in  springs ;  by  some  it  is  referred  to  different  states  of  elec- 
tricity ;  by  others  the  elasticity  is  considered  to  reside  in  the  thin 
blue,  oxidized  surface,  the  removal  of  which  is  thought  to  destroy 
the  elasticity,  much  in  the  same  manner  that  the  elasticity  of  a 
cane  is  greatly  lost  by  stripping  off  its  silicious  rind.  The  elastic- 
ity of  a  thick  spring  is  certainly  much  impaired  by  grinding  off 
a  small  quantity  of  its  exterior  metal,  which  is  harder  than  the 
inner  portion ;  and  perhaps  thin  springs  sustain  in  the  polishing  a 
proportional  loss,  which  is  to  them  equally  fatal. 

It  has  been  stated  that  the  bare  removal  of  the  blue  tint  from  a 
pendulum  spring,  by  its  immersion  in  weak  acid,  caused  the 
chronometer  to  lose  nearly  one  minute  each  hour ;  a  second  and 
equal  immersion  scarcely  caused  any  further  loss.  It  is  supposed 
springs  get  stronger,  in  a  minute  degree,  during  the  first  two  or 
three  years  they  are  in  use,  from  some  atmospheric  change ;  when 
the  springs  are  coated  with  gold  by  the  electrotype  process,  no 


158  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

such  change  is  observable,  and  the  covering,  although  perfect,  may 
be  so  thin  as  not  to  compensate  for  the  loss  of  the  blue  oxidized 
surface. 

LESS  COMMON  EXAMPLES  OF  HARDENING,  AND  PRECAUTIONARY 
MEASURES. — English  writers  are  famous  all  over  the  world  for  dis- 
tributing between  themselves  and  their  friends  the  inventions  and 
discoveries  of  the  rest  of  mankind.  One  of  the  leading  points  of 
Jacob  Perkins's  discovery  is  disposed  of  in  an  original  manner  in 
the  following  paragraph.  I  thought  I  was  up  to  every  mode  in 
which  they  drag  in  their  friends  ;  but  this  mode  is  new  to  me. 

One  of  the  most  serious  evils  in  hardening  steel,  especially  in 
thick  blocks,  or  those  which  are  unequally  thick  and  thin,  is  their 
liability  to  crack,  from  the  sudden  transition ;  and  in  reference  to 
hardening  razors,  a  case  in  point :  Mr. mentions  it  as  the  ob- 
servation and  practice  of  one  of  his  workmen,  "that  the  charcoal 
fire  should  be  made  up  with  shavings  of  leather  ;"  and  upon  being 
asked  what  good  he  supposed  the  leather  could  do,  this  workman 
replied,  "that  he  could  take  upon  him  to  say  that  he  never  had  a 
razor  crack  in  the  hardening  since  he  had  used  this  method,  though 
it  was  a  frequent  occurrence  before." 

When  brittle  substances  crack  in  cooling,  it  always  happens 
from  the  outside  contracting  and  becoming  too  small  to  contain 
the  interior  parts.  But  it  is  known  that  hard  steel  occupies  more 
space  than  when  soft ;  and  it  may  easily  be  inferred  that  the  nearer 
the  steel  approaches  to  the  state  of  iron,  the  less  will  be  this  in- 
crease of  dimensions.  If,  then,  we  suppose  a  razor  or  any  other 
piece  of  steel  to  be  heated  in  an  open  fire  with  a  current  of  air 
passing  through  it,  the  external  part  will,  by  the  loss  of  carbon, 
become  less  steely  than  before  ;  and  when  the  whole  piece  comes 
to  be  hardened,  the  inside  will  be  too  large  for  the  external  part, 
which  will  probably  crack.  But  if  the  piece  of  steel  be  wrapped 
up  in  the  cementing  mixture,  or  if  the  fire  itself  contain  animal 
coal,  and  is  put  together  so  as  to  operate  in  the  manner  of  that 
mixture,  the  external  part,  instead  of  being  degraded  by  this  heat, 
will  be  more  carbonated  than  the  internal  part,  in  consequence  of 
which  it  will  be  so  far  from  splitting  or  bursting  during  its  cooling 
that  it  will  be  acted  upon  in  a  contrary  direction,  tending  to 
render  it  more  dense  and  solid. 

The  cracking  which  so  often  occurs  on  the  immersion  of  steel 
articles  in  water,  does  not  appear  to  arise  so  much  from  any  decar- 
bonization  of  the  surface  merely,  as  from  the  sudden  condensation 
and  contraction  of  a  superficial  portion  of  the  metal,  while  the 
mass  inside  remains  swelled  with  the  heat,  and  probably  expands 
for  a  moment,  on  the  outside  coming  in  contact  with  the  water. 

The  file-makers,  to  save  their  works  from  clinking  or  cracking 
partly  through  in  hardening,  draw  the  files  through  yeast,  beer- 
grounds,  or  any  sticky  material,  and  then  through  a  mixture  of 
common  salt  and  animal  hoof  roasted  and  pounded.  This  is  cor- 
roborative of  the  above,  as  in  the  like  manner  it  supplies  a  little 


HARDENING  AND   TEMPERING.  159 

carbon  to  the  outside,  and  also  renders  the  steel  somewhat  harder 
and  less  disposed  to  crack  ;  the  composition  also  renders  the  more 
important  service  of  protecting  the  fine  points  of  the  teeth  from 
being  injured  by  the  fire. 

An  analogous  method  is  now  practised  in  hardening  Murphy's 
axletrees,  which  are  of  wrought-iron,  with  two  pieces  of  steel 
welded  into  the  lower  side,  where  they  rest  upon  the  wheels  and 
sustain  the  load.  .  The  work  is  heated  in  an  open  forge  fire,  quite 
in  the  ordinary  way,  and  when  it  is  removed,  a  mixture,  principally 
the  prussiate  of  potash,  is  laid  upon  the  steel ;  the  axletree  is  then 
immediately  immersed  in  water,  and  additional  water  is  allowed  to 
fall  upon  it  from  a  cistern.  The  steel  is  considered  to  become  very 
materially  harder  for  the  treatment,  and  the  iron  around  the  same 
is  also  partially  hardened. 

These  are,  in  fact,  applications  of  the  case-hardening  process 
which  is  usually  applied  to  wrought-iron  for  giving  it  a  steely  ex- 
terior, as  the  name  very  properly  implies.  Occasionally,  steel 
which  hardens  but  imperfectly,  either  from  an  original  defect  in 
the  material,  or  from  its  having  become  deteriorated  by  bad  treat- 
ment, or  too  frequent  passage  through  the  fire,  is  submitted  to  the 
case-hardening  process  in  the  ordinary  way,  by  inclosing  the 
objects  in  iron  boxes,  as  will  be  explained. 

Jacob  Perkins's  admirable  process  of  transfer  engraving  may  be 
thus  explained.  A  soft  steel  plate  was  first  engraved  with  the  re- 
quired subject  in  the  most  finished  style  of  art,  either  by  hand  or 
mechanically,  or  the  two  combined,  and  the  plate  was  then  hard- 
ened. A  decarbonized  steel  cylinder  was  next  rolled  over  the 
hardened  plate  by  powerful  machinery  until  the  engraved  impres- 
sion appeared  in  relief,  the  hollow  lines  of  the  original  becoming 
ridges  upon  the  cylinder.  The  roller  was  reconverted  to  the  con- 
dition of  ordinary  steel  and  hardened,  after  which  it  served  for 
returning  the  impression  to  any  number  of  decarbonized  plates, 
every  one  of  which  became  absolutely  a  counterpart  of  the  original ; 
and  every  plate,  when  hardened,  would  yield  the  enormous  num- 
ber of  150,000  impressions  without  any  perceptible  difference 
between  the  first  and  the  last. 

In  the  event  of  any  accident  occurring  to  the  transfer  roller,  the 
original  plate  still  existed,  from  which  another  or  any  required 
number  of  rollers  could  be  made,  and  from  these  rollers  any  num- 
ber of  new  plates,  all  capable  of  producing  as  many  impressions  as 
above  cited. 

The  present  practice  at  the  Bank  of  England,  introduced  by 
the  late  Mr.  John  Oldham,  and  now  under  the  superintendence  of 
his  son,  Mr.  Thomas  Oldharn,  is  to  anneal  at  one  time  four  cast-iron 
boxes,  each  containing  from  three  to  six  steel  plates,  surrouii'lrd 
on  all  sides  with  fine  charcoal  mixed  with  an  equal  quantity  of 
chalk  and  driven  in  hard. 

The  reverberatory  furnace  employed  has  a  circular  cast-iron 
plate  or  bed  upon  which  tlu)  four  boxes  are  fastened  by  wr 


160  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

and  as  the  plate  revolves  very  slowly  and  continually  by  the  steam- 
engine  employed  in  working  the  printing-presses  and  other  ma- 
chinery, the  plates  are  exposed  in  the  most  equal  manner  to  the 
heat,  and  when  the  proper  temperature  is  attained  all  the  apertures 
are  carefully  closed  and  luted,  to  extend  the  cooling  over  a  space 
of  at  least  forty-eight  hours. 

The  surfaces  of  the  cylinders  and  plates  are  thus  rendered  ex- 
ceedingly soft,  to  the  depth  of  about  the  32d  of  an  inch,  "  so  as  to 
become  more  like  lead  than  any  thing  else,"  and  thus  much  of 
their  surfaces  must  be  turned  or  planed  off;  the  device  is  raised  in 
the  transfer-press  upon  the  natural  soft  steel  of  the  rollers,  under  a 
pressure  of  some  tons,  and  these  are  hardened  without  any  inten- 
tional application  of  the  case-hardening  process,  as  the  simple  steel 
is  undoubtedly  very  superior  in  all  respects  to  that  which  has  been 
decarbonized  and  reconverted. 

The  plates  themselves  are  used  in  the  soft  state,  as  they  then 
admit  of  reparation  by  the  transfer  rollers ;  and  the  process  is 
found  to  be  more  economical,  as  the  risk  of  warping  is  avoided, 
and  they  may  be  easily  repaired.  The  dates  and  numbers  are  at 
present  printed  as  a  second  process  by  letter-press  printing,  with 
the  machines  invented  by  the  late  Mr.  Bramah,  and  which  have 
been  engraved  and  described  in  different  books. 

In  hardening  engraved  plates,  rollers,  dies,  and  similar  works,  it 
is  of  the  greatest  importance  to  preserve  the  surface  unimpaired, 
and  as  steel  is  very  liable  to  oxidation  at  the  red  heat  if  exposed  to 
the  air  for  even  a  few  seconds,  and  which  oxidized  scale  will  in 
some  cases  nearly  remove,  or  at  any  rate  injure,  the  subject  produced 
upon  its  surface,  it  is  of  great  importance  to  conduct  the  heating 
and  cooling  with  the  most  complete  exclusion  of  the  air. 

Mr.  Thomas  Oldham  has,  more  recently,  introduced  a  mode  of 
proceeding  which  appears  as  near  to  perfection  as  possible,  and  by 
it,  instead  of  the  works  acquiring  the  ordinary  black  and  gray 
tints,  and  a  minute  roughness,  like  the  surface  of  the  finest  emery 
paper,  the  steel  comes  out  of  the  water  as  smooth  to  the  touch  as 
at  first,  and  mottled  with  all  the  beautiful  tints  seen  on  case-hard- 
ened gun-locks.  The  method  is  simply  as  follows  : 

The  work  to  be  hardened  is  inclosed  in  a  wrought-iron  box  with 
a  loose  cover,  a  false  bottom,  and  with  three  ears  projecting  from  its 
surface  about  midway  ;  the  steel  is  surrounded  on  all  sides  with  car- 
bon from  leather,  driven  in  hard,  and  the  cover  and  bottom  are 
carefully  luted  with  moist  clay.  Thus  prepared,  the  case  is  placed 
in  the  vertical  position,  in  a  bridle  fixed  across  a  great  tub,  which 
is  then  filled  with  water  almost  to  touch  the  false  bottom  of  the 
case.  The  latter  is  now  heated  in  the  furnace  as  quickly  as  will 
allow  the  uniform  penetration  of  the  heat. 

When  sufficiently  hot,  it  is  removed  to  its  place  in  the  hardening 
tub,  the  cover  of  the  iron  box  is  removed,  and  the  neck  or  gudgeon 
of  the  cylinder  is  grasped,  beneath  the  surface  of  the  carbon,  with  a 
long  pair  cf  tongs,  upon  which  a  coupler  is  dropped  to  secure  the 


HARDENING   AND   TEMPERING.  161 

grasp.  It  only  remains  for  the  individual  to  hold  the  tongs  with  a 
glove  whilst  a  smart  tap  of  a  hammer  is  given  on  their  extremity  ; 
this  knocks  out  the  false  bottom,  of  the  case,  and  the  cylinder  and  ' 
tongs  are  instantly  immersed  in  the  water ;  the  tongs  prevent  the 
cylinder  from  falling  on  its  side,  and  thus  injuring  its  delicate  hut 
still  hot  surface.  For  square  plates,  a  suitable  frame  is  attached  by 
four  slight  claws,  and  it  is  the  frame  which  is  seized  by  the  tongs : 
the  latter  are  sometimes  held  by  a  chain,  which  removes  the  risk 
of'  accident  to  the  individual.  In  some  cases,  the  work  assumes  a 
striated  and  mackled  appearance,  evident  to  the  touch  as  well  as 
the  sight,  and  which  is  to  be  attributed  to  an  imperfect  manufacture 
of  the  steel. 

Mr.  Oldham  informs  me  that  in  the  Paris  Mint,  the  dies  are  in- 
closed in  the  soot  of  burnt  wood ;  and  that  in  the  Koyal  mint  the 
dies  are  hardened  by  a  powerful  jet  of  water.  He  also  adds,  that 
his  workpeople  have  the  impression  that  steel  is  reduced  to  its  softest 
state  by  enclosure  with  lime  and  ox-gall. 

Various  methods  have  been  likewise  attempted  to  prevent  the 
distortions  to  which  work  is  liable  in  the  operation  of  hardening, 
but  without  any  very  advantageous  results;  for  instance,  it  has 
been  recommended  to  harden  small  cylindrical  wires,  by  rolling 
them  when  heated  between  cold  metallic  surfaces  to  retain  them 
perfectly  straight.  This  might  probably  answer,  but  unfortunately 
cylindrical  steel  wires  supply  but  a  very  insignificant  portion  of 
our  wants. 

Another  mode  tried  by  Dr.  "Wollaston  was  to  inclose  the  piece 
of  steel  in  a  tube  filled  with  Newton's  fusible  alloy,  the  whole  to 
be  heated  to  redness  and  plunged  in  cold  water :  the  object  was  re- 
leased by  immersion  in  boiling  water,  which  melted  the  alloy,  and 
the  piece  came  out  perfectly  unaltered  in  form,  and  quite  hard. 
This  mode  is  too  circuitous  for  common  practice,  and  the  reason 
why  it  is  to  be  always  successful  is  not  very  apparent. 

Is  not  this  a  base  attempt  to  drag  in  Newton  and  Wollaston  ? 
To  these  men  the  English  attribute  every  thing.  Jacob  Perkins 
was  an  American  to  whom  all  the  credit  is  due.  The  two  Oldhams 
were  Irishmen,  Brunei  was  a  Frenchman,  and  Bramah  was  a 
German. 

Mr.  Perkins  resorted  to  a  very  simple  practice  with  the  view  of 
lessening  the  distortion  of  his  engraved  steel  plates  by  boiling  the 
water  in  which  they  were  to  be  hardened  to  drive  off  the  air,  and 
plunging  them  vertically;  and  as  the  plates  were  required  to  be 
tempered  to  a  straw  color,  instead  of  allowing  them  to  remain  in 
the  water  until  entirely  cold,  he  removed  them  whilst  the  inside 
was  still  hot,  and  placed  them  on  the  top  of  a  clear  fire  until  the 
tallow  with  which  they  were  rubbed,  smoked ;  the  plate  was  then 
returned  to  the  water  for  a  few  moments,  and  so  on  alternately  until 
they  were  quite  cold,  the  surface  never  being  allowed  to  exceed 
the  tempering  heat. 

From  various  observations,  it  appears  on  the  whole  to  be  the 
11 


162  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

best  in  thick  works  thus  to  combine  the  hardening  and  tempering 
processes,  instead  of  allo\ying  the  objects  to  become  entirely  cold, 
and  then  to  reheat  them  for  tempering.  To  ascertain  the  time 
when  the  plate  should  be  first  removed  from  the  water,  Mr.  Perkins 
heated  a  piece  of  steel  to  the  straw  color,  and  dipped  it  into  water 
to  learn  the  sound  it  made ;  and  when  the  hardened  plate  caused  the 
same  sound,  it  was  considered  to  be  cooled  to  the  right  degree,  and 
was  immediately  withdrawn. 

I  will  conclude  these  numerous  examples  and  remarks  by  one 
of  a  very  curious,  massive,  and  perfect  kind,  in  which  the  hardening 
is  sure  to  occur  without  loss  of  figure,  unless  the  work  break  under 
the  process.  I  refer  to  the  locomotive  wheels  with  hardened  steel 
tires,  which  may  be  viewed  as  the  most  ponderous  example  of 
hardening,  as  the  tires  of  the  eight-foot  wheels  weigh  about  10  cwt., 
and  consist  of  about  one-third  steel,  and  there  seems  no  reason  why 
this  diameter  might  not  be  greatly  exceeded. 

The  materials  for  the  tires  are  first  swaged  separately,  and  then 
welded  together  under  the  heavy  hammer  at  the  steel- works,  after 
which  they  are  bent  to  the  circle,  welded,  and  turned  to  certain 
gages.  The  tire  is  now  heated  to  redness  in  a  circular  furnace : 
during  the  time  it  is  getting  hot,  the  iron  wheel,  previously  turned 
to  the  right  diameter,  is  bolted  down  upon  a  face-plate ;  the  tire  ex- 
pands with  the  heat,  and  when  at  a  cherry-red,  it  is  dropped  over 
the  wheel,  for  which  it  was  previously  too  small,  and  is  also  hastily 
bolted  down  to  the  surface  plate,  the  whole  load  is  quickly  im- 
mersed by  a  swing  crane  into  a  tank  of  water  about  five  feet  deep, 
and  hauled  up  and  down  until  nearly  cold ;  the  steel  tires  are  not 
afterwards  tempered. 

The  spokes  are  forged  out  of  flat  bars  with  T  formed  heads ; 
these  are  arranged  radially  in  the  founder's  mould,  whilst  the  cast- 
iron  centre  is  poured  around  them :  the  ends  of  the  T  heads  are 
then  welded  together  to  constitute  the  periphery  of  the  wheel  or 
inner  tire,  and  little  wedge-form  pieces  are  inserted  where  there  is 
any  deficiency  of  iron. 

The  wheel  is  then  chucked  on  a  lathe,  bored,  and  turned  on  the 
edge,  not  cylindrically,  but  like  the  meeting  of  two  cones,  and 
about  one  quarter  of  an  inch  higher  in  the  middle  than  on  the 
two  edges.  The  compound  tire  is  turned  to  the  corresponding 
form,  and  consequently  larger  within  or  under-cut,  so  that  the 
shrinking  secures  the  tire  without  the  possibility  of  obliquity  or 
derangement,  and  no  rivets  are  required.  It  sometimes  happens 
that  the  tire  breaks  in  shrinking  when  by  mismanagement  the 
diameter  of  the  wheel  is  in  excess. 


HARDENING   CAST  AND   WROUGHT-IRON.  163 

CHAPTER  X. 

HARDENING   CAST   AND   WROUGHT-IRON. 


J_  tL  CJ       OlillillUUViC?       UUL       V/UV>IlllAw/C**.L      VWU.OUJ.UU.U1A./1J.        WVVTJwW      QlA^v^lj        f?  Ul 

usually  contains  about  one  per  cent,  of  carbon,  and  cast-iron  that  1: 
from  three  to  six  or  seven  per  cent.,  naturally  leads  to  the  expectati 


THE  similitude  of  chemical  constitution  between  steel,  which 

and  cast-iron  that  has 
tion 

of  some  correspondence  in  their  characters,  and  which  is  found  to 
exist.  Thus  some  kinds  of  cast-iron  will  harden  almost  like  steel,  but 
they  generally  require  a  higher  temperature ;  and  the  majority  of 
cast-iron,  also  like  steel,  assumes  different  degrees  of  hardness, 
according  to  the  rapidity  with  which  the  pieces  are  allowed  to 
cool. 

The  casting  left  undisturbed  in  the  mould,  is  softer  than  a  similar 
one  exposed  to  the  air  soon  after  it  has  been  poured.  Large 
castings  cannot  cool  very  hastily,  and  are  seldom  so  hard  as  the 
small  pieces,  some  of  which  are  hardened  like  steel  by  -the  moisture 
combined  with  the  moulding  sand,  and  cannot  be  filed  until  they 
have  been  annealed  after  the  manner  of  steel,  which  renders  them 
soft  and  easy  to  be  worked. 

Chilled  iron-castings  present  as  difficult  a  problem  as  the  harden- 
ing and  tempering  of  steel ;  the  fact  is  simply  this,  that  iron  cast- 
ings, made  in  iron  moulds  under  particular  circumstances,  become 
on  their  outer  surfaces  perfectly  hard,  and  resist  the  file  almost 
like  hardened  steel ;  the  effect  is  however  superficial,  as  the  chilled 
exterior  shows  a  distinct  line  of  demarkation  when  the  objects  are 
broken. 

The  production  of  chilled  castings  is  always  a  matter  of  some 
uncertainty,  and  depends  upon  the  united  effect  of  several  causes ; 
the  quality  of  the  iron,  the  thickness  of  the  casting,  the  tempera- 
ture of  the  iron  at  the  time  of  pouring,  and  the  condition  or 
temperature  of  the  iron  mould,  which  has  a  greater  effect  in 
u  striking  in"  when  the  mould  is  heated  than  if  quite  cold :  a  very 
thin  stratum  of  earthy  matter  will  almost  entirely  obviate  the 
chilling  effect.  A  cold  mould  does  not  generally  chill  so  readily 
as  one  heated  nearly  to  the  extent  called  "black-hot:"  but  the  re- 
verse conditions  occur  with  some  cast-iron.  The  hard  portion 
varies  from  less  than  one-sixteenth  to  more  than  one-fourth  of  au 
inch  in  thickness. 

There  is  this  remarkable  difference  between  east-iron  thus  hard- 
ened, and  steel  hardened  by  plunging  whilst  hot  into  water ;  that 
whereas  the  latter  is  softened  again  by  a  dull  red-heat,  the  chilled 
castings  on  the  contrary  are  turned  out  of  the  moulds  as  soon  as 
the  metal  is  set,  and  are  allowed  to  cool  in  the  air;  yet  although 
the  whole  is  at  a  bright  red  heat,  no  softening  of  the  chilled  part 
takes  place.  This  material  has  been  employed  for  punches  for  red- 
hot  iron;  the  punches  were  fixed  in  cast-iron  sockets,  from  which 


164  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

they  only  projected  sufficiently  to  perforate  the  wheel  tires  in  the 
formation  of  which  they  were  used,  and  from  retaining  their  hard- 
ness they  were  more  efficient  than  those  punches  made  of  steel. 

Chilled  castings  are  also  commonly  employed  for  axletree  boxes, 
and  naves  of  wheels,  which  are  finished  by  grinding  only ;  also  for 
cylinders  for  rolling  metal,  for  the  heavy  hammers  and  anvils  or 
stithies  for  iron  works,  the  stamp-heads  for  pounding  metallic  ores, 
etc.  Cannon  balls,  as  well  as  ploughshares,  are  examples  of  chilled 
castings ;  with  balls  the  chilling  is  unimportant,  and  occurs  alone 
from  the  method  essential  to  giving  the  balls  the  required  perfec- 
tion of  form  and  size. 

Malleable  iron-castings  are  at  the  opposite  extreme  of  the  scale, 
and  are  rendered  externally  soft  by  the  abstraction  of  their  carbon, 
whereby  they  are  nearly  reduced  to  the  condition  of  pure  malleable 
iron,  but  without  the  fibre  which  is  due  to  the  hammering  and 
rolling  employed  at  the  forge. 

The  malleable  iron-castings  are  made  from  the  rich  iron,  and  are 
at  first  as  brittle  as  glass  or  hardened  steel ;  they  are  enclosed  in 
iron  boxes  of  suitable  size,  and  surrounded  with  pounded  iron- 
stone, or  some  of  the  metallic  oxides,  as  the  scales  from  the  iron 
forge,  or  with  common  lime,  and  various  other  absorbents  of  carbon, 
used  either  together  or  separately.  The  cases,  which  are  sometimes 
as  large  as  barrels,  are  luted,  rolled  into  the  ovens  or  furnaces,  and 
submitted  to  a  good  heat  for  about  five  days,  and  are  then  allowed 
to  cool  very  gradually  within  the  furnaces. 

The  time  and  other  circumstances  determine  the  depth  of  the 
effect ;  thin  pieces  become  malleable  entirely  through ;  they  are 
then  readily  bent,  and  may  be  slightly  forged  ;  cast-iron  nails  and 
tacks  thus  treated  admit  of  being  clenched,  thicker  pieces  retain  a 
central  portion  of  cast-iron,  but  in  a  softened  state,  and  not  brittle 
as  at  first ;  on  sawing  them  through,  the  skin  or  coat  of  soft  iron  is 
perfectly  distinct  from  the  remainder. 

This  mode  is  particularly  useful  for  thin  articles  that  can  be  more 
economically  and  correctly  cast,  than  wrought  at  the  forge,  as 
bridle-bits,  snuffers,  parts  of  locks,  culinary  and  other  vessels,  pokers 
and  tongs,  many  of  which  are  subsequently  case-hardened  and 
polished,  as  will  be  explained,  but  malleable  cast-iron  should  never 
be  used  for  cutting-tools. 

CASE-HARDENING  WROUGHT  AND  CAST-IRON.— The  property  of 
hardening  is  not  possessed  by  pure  malleable  iron;  but  I  have  now 
to  explain  a  rapid  and  partial  process  of  cementation,  by  which 
wrought-iron  is  first  converted  exteriorly  into  steel,  and  is  subse- 
quently hardened  to  that  particular  depth ;  leaving  the  central 
parts  in  their  original  condition  of  soft  fibrous  iron.  The  process 
is  very  consistently  called  case-hardening,  and  is  of  great  import- 
ance in  the  mechanical  arts,  as  the  pieces  combine  the  economy, 
strength,  and  internal  flexibility  of  iron,  with  a  thin  casting  of  steel ; 
which,  although  admirable  as  an  armor  of  defence  from  wear  or 
deterioration  as  regards  the  surface,  is  unfit  for  the  formation  of 


HARDENING   CAST  AND  WROUGHT-IRON.  165 

cutting  edges  or  tools,  owing  to  the  entire  absence  of  hammering, 
subsequent  to  the  cementation  with  the  carbon.  Cast-iron  obtains 
in  like  manner  a  coating  of  steel,  which  surrounds  the  peculiar 
shape  the  metal  may  have  assumed  in  the  iron-foundry  and  work- 
shop. 

The  principal  agents  used  for  case-hardening  are  animal  matters., 
as  the  hoofs,  horns,  bones,  and  skins  of  animals ;  these  are  nearly 
alike  in  chemical  constitution;  they  are  mostly  charred  and 
coarsely  pounded ;  some  persons  also  mix  a  little  common  salt 
with  some  of  the  above.  The  work  should  be  surrounded  on  all 
sides  with  a  layer  from  half  an  inch  to  one  inch  thick. 

The  methods  pursued  by  different  individuals  do  not  greatly 
differ;  for  example,  the  gunsmith  inserts  the  iron  work  of  the  gun- 
lock,  in  a  sheet-iron  case  in  the  midst  of  bone-dust  (often  not 
burned),  the  lid  of  the  box  is  tied  on  with  iron  wire,  and  the  joint 
is  luted  wth  clay ;  it  is  then  heated  to  redness  as  quickly  as  possible, 
and  retained  at  that  heat  from  half  an  hour  to  an  hour,  and  the 
contents  are  quickly  immersed  in  cold  water.  The  objects  sought 
are  a  steely  exterior,  and  a  clean  surface  covered  with  the  pretty 
mottled  tints,  apparently  caused  by  oxidation  from  the  partial 
admission  of  air. 

Some  of  the  malleable  iron  castings,  such  as  snuffers,  are  case- 
hardened  to  admit  of  a  better  polish ;  it  is  usually  done  with  burnt 
bone-dust,  and  at  a  dull  red  heat ;  they  remain  in  the  fire  about 
two  or  three  hours,  and  should  be  immersed  in  oil,  as  it  does  not 
render  them  quite  so  brittle  as  when  plunged  into  water.  It  must 
be  remembered  they  are  sometimes  changed  throughout  their  sub- 
stance into  an  inferior  kind  of  steel,  by  a  process  that  should  in 
such  instances  be  called  cementation,  and  not  case-hardening,  con- 
sequently they  will  not  endure  violence. 

The  mechanician  and  engineer  use  horns,  hoofs,  bone-dust,  and 
leather,  and  allow  the  period  to  extend  from  two  to  eight  hours, 
most  generally  four  or  five;  sometimes  for  its  greater  penetration, 
the  process  is  repeated  a  second  time  with  new  carbonaceous 
materials.  Some  open  the  box  and  immerse  the  work  in  water 
direct  from  the  furnace ;  others,  with  the  view  to  preserve  a  better 
surface,  allow  the  box  to  cool  without  being  opened,  and  harden 
the  pieces  with  the  open  fire  as  a  subsequent  operation ;  the  carbon 
once  added,  the  work  may  be  annealed  and  hardened  much  the 
same  as  ordinary  steel. 

When  the  case-hardening  is  required  to  terminate  at  any  par- 
ticular part,  as  a  shoulder,  the  object  is  left  with  a  band  or  projec- 
tion, the  work  is  allowed  to  cool  without  being  immersed  in  water 
the  band  is  turned  offj  and  the  work  when  hardened  in  the  open 
fire  is  only  affected  so  far  as  the  original  cemented  surface 
remains. 

A  new  substance  for  the  case-hardening  process,  but  containing 
the  same  elements  as  those  more  commonly  employed,  has  of  late 
years  been  added,  namely,  the  prussiate  of  potash  (a  salt  consisting 


166  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

of  two  atoms  of  carbon  and  one  of  nitrogen),  which  is  made  from  a 
variety  of  animal  matters. 

It  is  a  new  application  without  any  change  of  principle;  the 
time  occupied  in  this  steelifying  process  is  sometimes  only  min- 
utes instead  of  hours  and  days,  as  for  example  when  iron  is 
heated  in  the  open  fire  to  a  dull  red,  and  the  prussiate  is  either 
sprinkled  upon  it  or  rubbed  on  in  the  lump,  it  is  returned  to  the 
fire  for  a  few  minutes  and  immersed  in  water;  but  the  process  is 
then  exceedingly  superficial,  and  it  may  if  needful  be  limited  to 
any  particular  part  upon  which  alone  the  prussiate  is  applied. 
The  effect  by  many  is  thought  to  be  partial  or  in  spots,  as  if  the 
salt  refused  to  act  uniformly;  in  the  same  manner  that  water 
only  moistens  a  greasy  surface  in  places. 

The  prussiate  of  potash  has  been  used  for  case-hardening  the 
bearings  of  wrought-iron  shafts,  but  this  seems  scarcely  worth  the 
doing. 

In  the  general  way,  the  conversion  of  the  iron  into  steel,  by 
case-hardening,  is  quite  superficial,  and  does  not  exceed  the  six- 
teenth of  an  inch;  if  made  to  extend  to  one-quarter  or  three-eighths 
of  an  inch  in  depth,  to  say  the  least  it  would  be  generally  useless, 
as  the  object  is  to  obtain  durability  of  surface,  with  strength  of  in- 
terior, and  this  would  disproportionately  encroach  on  the  strong 
iron  within.  The  steel  obtained  in  this  adventitious  manner  is  not 
equal  in  strength  to  that  converted  and  hammered  in  the  usual 
way,  and  if  sent  in  so  deeply,  the  provision  for  wear  would  far 
exceed  that  which  is  required. 

Let  us  compare  the  case-hardening  process  with  the  usual  con- 
version of  steel.  The  latter  requires  a  period  of  about  seven  days, 
and  a  very  pure  carbon,  namely,  wood  charcoal,  of  which  a  minute 
portion  only  is  absorbed ;  and  it  being  a  simple  body,  when  the 
access  of  air  is  prevented  by  the  proper  security  of  the  troughs, 
the  bulk  of  the  charcoal  remains  unconsumed,  and  is  reserved  for 
future  use,  as  it  has  undergone  no  change.  The  hasty  and  partial 
process  of  cementation  is  produced  in  a  period  commonly  less  than 
,as  many  hours  with  the  animal  charcoal,  or  than  as  many  minutes 
with  the  prussiate  of  potash ;  but  all  these  are  compound  bodies 
(which  contain  cyanogen,  a  body  consisting  of  carbon  and  nitrogen), 
and  are  never  used  a  second  time,  but  on  the  contrary  the  process 
is  often  repeated  with  another  dose.  It  would  be,  therefore,  an 
interesting  inquiry  for  the  chemist,  as  to  whether  the  cyanogen  is 
absorbed  after  the  same  manner  as  carbon  in  ordinary  steel,  or 
whether  the  nitrogen  assists  in  any  way  in  hastening  the  admission 
of  the  carbon,  by  some  as  yet  untraced  amnity  or  decomposition.  It 
may  happen  that  the  carbon  is  not  essential,  as  the  Indian  steel  or 
wootz  is  stated  to  contain  alumina,  silex,  and  manganese. 

This  hasty  supposition  will  apply  less  easily  to°cast-iron,  which 
contains  from  three  to  seven  times  as  much  carbon  as  steel,  and 
although  not  always  hardened  by  simple  immersion,  is  constantly 
under  the  influence  of  the  case-hardening  process ;  unless  we  adopt 


APPLICATION   OF    IRON   TO   SHIP-BUILDING.  167 

the  supposition,  that  the  carbon  in  cast-iron  which  is  mixed  with 
the  metal  in  the  shape  of  cinder  in  the  blast  furnace,  when  all  is  in 
a  fluid  state,  is  in  a  less  refined  union  than  that  instilled  in  a  more 
aeriform  condition  in  the  acts  of  cementation  and  case-hardening. 


CHAPTER  XL 

OX   THE   APPLICATION   OF   IRON   TO   SHIP-BUILDING. 

THERE  is  probably  no  branch  of  industry  in  which  the  use  of 
iron  is  more  important  than  that  of  ship-building.  The  strength, 
ductility,  and  comparative  lightness  of  this  material  are  all  in  its 
favor ;  and,  although  much  has  been  done  in  the  application  of 
iron  to  this  important  purpose,  a  great  deal  more  remains  to  b^ 
accomplished. 

Vessels  composed  of  iron  plates  have  been  employed  for  more 
than  fifty  years  in  the  navigation  of  canals ;  but  it  is  not  more! 
than  twenty-five  or  twenty-six  since  they  were  first  introduced  as 
sea-going  vessels.  It  is  true  that  the  late  Mr.  Aaron  Manby  pro- 
jected an  iron  vessel  in  1820,  which  was  built  in  the  ensuing  year, 
and  early  in  1822  was  navigated  by  Captain  (since  Admiral  Sir 
*  Charles)  Napier  from  London  to  Havre,  and  on  to  Paris ;  this, 
however,  was  not  a  sea-going  vessel,  but  an  iron  steamer  con- 
structed for  the  Seine,  and  which  for  many  years  navigated  that 
river  between  Paris  and  Rouen. 

From  this  period  little  appears  to  have  been  done  in  furtherance 
of  the  application  of  iron  to  the  construction  of  ships  till  1829-30, 
when  the  introduction  of  a  new  system  of  traction  at  high  veloci- 
ties on  canals  led  to  new  developments ;  and  from  this  time  to  the 
present,  iron,  as  a  material  for  ship-building,  has  been  extensively 
used,  and  is  increasingly  in  demand.  From  1829  to  1832,  iron 
ship-building  may  be  considered  to  have  been  experimental ;  and 
the  trials  conducted  by  Mr.  Fairbairn  on  the  Forth  and  Clyde 
Canal,*  simultaneously  with  those  of  Mr.  John  and  Mr.  McGregor 
Laird  at  Liverpool,  led  to  a  new  era  in  the  history  of  ship-building. 

Among  the  first  iron  vessels  for  sea-going  purposes  was  one  of 
small  tonnage,  built  at  Manchester  for  the  Forth  and  Clyde  Canal 
Company.  She  was  built  with  paddle-wheels  on  the  quarter  near 
the  stern,  and  propelled  by  two  high-pressure  engines  of,  collectively, 
80  horse-power.  This  vessel  attained  great  speed,  considering  the 
date  at  which  she  was  built ;  and  for  many  years  traded  between 
Grangemouth  and  the  coast  of  Fife,  round  to  Dundee. 

Previously  to  the  building  of  the  "  Manchester,"  another  small 
vessel,  called  the  "  Lord  Dundas,"  was  constructed  for  the  same 

*  Vide  "  Remarks  on  Canal  Navigation,"  by  W.  Fairbairn.     Longman,  1831. 


168  THE  PRACTICAL   METAL- WORKER'S   ASSISTANT. 

company.  She  was  strictly  experimental,  and  was  propelled  by  a 
locomotive  engine  of  16  horse-power,  with  8-inch  cylinders.  Such 
was  the  lightness  of  her  construction,  that  the  plates  were  only 
l-14th  of  an  inch  thick,  riveted  to  light  T  iron,  which  formed  the 
ribs  of  the  hull.  This  vessel  had  stern  paddles,  and  was  of  the 
following  dimensions : — 

Length,  68  feet. 

Breadth  on  beam,  11  feet  6  inches. 

Depth,  4  feet  6  inches. 

Diameter  of  paddle-wheel,  9  feet. 

Whole  weight,  including  engine,  paddle-wheel,  etc.,  7  tons  16 
cwt. 

Draught  of  water  with  cargo  on  board,  16  inches. 
The  "  Lord  Dundas"  was  built  in  1830,  conveyed  through  the 
streets  of  Manchester  on  trucks,  and  launched  into  the  Irwell, 
where  numerous  trials  took  place  in  regard  to  her  speed  in  narrow 
channels,  such  as  canals ;  including  such  other  direct  experiments 
as. were  likely  to  result  from  vessels  of  this  kind  propelled  by 
steam.  Subsequently  to  these  trials  she  was  navigated  to  Liver- 
pool, and  from  thence  to  Glasgow  via  the  Isle  of  Man.  As  this 
voyage  was  rather  a  perilous  one,  when  the  slightness  of  the  vessel's 
build  and  the  thinness  of  her  sheathing-plates  are  considered,  and 
as  it  was  among  the  first — if,  indeed,  it  were  not  the  very  first — 
which  indicated  the  necessity  of  adjusting  the  compass  in  order  to 
neutralize  the  local  attraction  of  the  material  by  which  it  was  sur-  < 
rounded,  we  may  probably  be  permitted  to  give  a  brief  narrative  of 
the  circumstances  as  they  occurred  during  the  voyage.  The  "Lord 
Dundas"  sailed  from  Liverpool  at  four  A.M.  on  a  fine  morning  in 
June,  1831,  and  steered  .direct  for  the  floating-light.  She  made  the 
light  in  good  time,  notwithstanding  a  thick  haze  in  the  atmos- 
phere, which,  during  the  forenoon,  thickened  into  a  dense  fog.  To- 
wards one  o'clock  land  was  descried  upon  the  starboard  bow,  show- 
ing apparently  that  she  had  made  considerable  deviation  in  a  west- 
erly direction.  A  dispute  arose  as  to  what  land  it  was — one  party 
contending  that  it  was  the  western  side  of  the  Isle  of  Man  ;  the 
other,  better  acquainted  with  that  side  of  the  island,  that  it  was 
not.  After  a  considerable  contest  and  examination  of  the  charts, 
it  was  at  last  discovered  that  the  little  vessel  was  on  the  north  of 
Morecambe  Bay,  approaching  the  coast  of  Cumberland.  On  the 
discovery  of  this  error,  and  in  consequence  of  the  frail  bark  show- 
ing symptoms  of  weakness,  from  the  eftects  of  the  swell  which  was 
rolling  in  from  the  west,  it  was  considered  desirable  to  look  out 
for  shelter  ;  and  consequently  her  course  was  altered  in  the  direc- 
tion of  the  Island  of  Peel  Foundry,  where  she  was  sheltered  for 
the  night.  On  the  following  morning  she  crossed  to  Ramsey, 
where  the  question  of  the  variation  of  the  compass  was  investi- 
gated, and  rectified  by  the  simple  process  of  nailing  a  block  of 
iron  to  the  deck,  in  the  immediate  vicinity  of  the  compass — by 
this  means  neutralizing  the  local  attraction  of  the  iron  by  which 


APPLICATION   OF   IRON  TO   SHIP-BUILDING.  169 

it  was  surrounded.  After  this,  the  remainder  of  the  voyage  from 
Ramsey  to  Greenock  was  effected  in  a  direct  course  with  perfect 
safety. 

We  have  noticed  these  circumstances  as  illustrating  the  imper- 
fect state  of  our  knowledge,  as  respects  the  influence  of  large 
masses  of  iron  upon  the  ship's  compass.  It  has  been  ascertained . 
that  the  angle-iron  and  T  iron  ribs,  when  carried  above  the  deck 
so,  as  to  form  part  of  the  bulwarks,  had  a  remarkable  effect  upon 
the  compass,  each  of  them  forming,  as  it  were,  a  separate  magnet, 
whose  influence,  unless  neutralized  by  some  greater  magnetic  power, 
caused  a  considerable  deviation  of  the  needle,  so  that  it  indicated 
a  point  wide  of  the  magnetic  north ;  and  as  this  deviation  altered 
with  every  change  of  the  position  of  the  vessel,  no  reliance  could 
be  placed  upon  it.  Captain  Johnson  and  Professor  Airey,  by  an  in- 
teresting series  of  experiments,  ultimately  settled  this  question, 
and  provided  a  remedy  in  the  adjustment  and  correction  of  the 
compass  on  board  iron  ships. 

The  object  contemplated  by  this  light  vessel  and  light  machinery 
\yas,  to  ascertain  how  far  quick  speeds  could  be  attained  upon  canals 
by  steam-power.  As  much  as  fourteen  miles  an  hour  had  been 
accomplished  by  horses,  with  a  tractive  power  of  352  Ibs.  by  dyna- 
mometer, and  that  without  the  least  appearance  of  surge  ;*  but  the 
experiments  made  with  the  "Lord  Dundas"  steamer  indicated  a  very 
different  law,  and,  under  the  most  favorable  circumstances,  never 
exceeded  more  than  eight  to  eight  and  a  half  miles  an  hour,  and 
that  with  an  enormous  swell  washing  over  the  banks  of  the  canal 
in  every  direction.  In  fact,  the  object  for  which  the  boat  was 
built  was  never  attained,  and  it  was  found  impossible  to  effect  by 
steam  what  was  done  by  horses.  It  nevertheless  led  to  a  more 
important  and  a  greatly-enlarged  branch  of  industry — namely,  the 
construction  of  iron  vessels  upon  a  large  scale  for  ocean  traffic. 

These  experimental  vessels,  the  "Lord  Dundas"  and  the  "Man- 
chester," already  mentioned,  in  conjunction  with  the  "Alburka," 
and  some  other  vessels,  by  Messrs.  J.  Laird  and  Co.,  of  Liverpool, 
may  be  considered  as  the  first  successful  attempts  in  iron  ship- 
building. Shortly  after  the  completion  of  these  vessels,  several 
large  establishments  were  founded  for  this  branch  of  construction, 
amongst  whom  may  be  enumerated  Messrs.  W.  Fairbairn  and  Co., 
Millwall,  and  Messrs.  Ditchburn  and  Mare,  Blackwall,  London; 
Messrs.  Laird  and  Co.,  Liverpool ;  Messrs.  Tod  and  McGregor, 
Glasgow ;  and  several  others,  all  of  whom  were  engaged  for  many 
years  in  the  construction  of  iron  ships. 

In  this  chapter  we  shall  be  unable  to  go  much  into  detail,  and 
must  confine  ourselves  to  a  few  general  observations  in  connection 
with  the  more  important  application  of  iron  as  a  material  of  con- 
struction for  ocean  steamers  and  sailing  vessels,  exposed  to  all  the 
changes  and  vicissitudes  of  wind  and  tides  in  the  open  sea. 

*  "  Remarks  on  Canal  Navigation,"  page  57. 


170 


THE   PRACTICAL   METAL-WORKEK'S   ASSISTANT. 


Fig.  108. 


Fig.  108  exhibits  a  half  cross  section  of  one  of  Her  Majesty's 
frigates  of  the  second  class,  and  will,  to  a  certain  extent,  illustrate 

the  principles  of  construc- 
tion. It  will  be  seen  that 
the  iron-ship  is  composed 
of  a  series  of  frames  or  ribs, 
placed  at  various  distances 
apart ;  these  are  connected 
together  in  the  interior  of 
the  vessel  by  transverse 
beams,  mostly  of  iron,  but 
sometimes  of  wood,  which 
support  the  decks.  Over 
the  exterior  of  the  ribs  the 
iron  sheathing-plates  are 
riveted,  so  as  to  form  a 
continuous  water-tight  cov- 
ering over  the  entire  ex- 
terior of  the  vessel. 

EIBS. — One  of  the  ribs  is 
shown  at  a  a  a,  Fig.  108; 
and  its  section  will  be  seen 
in  Fig.  109,  which  is  a  longi- 
tudinal section  through  the 
line  b  b  •  it  consists  of  a 
vertical  plate  c,  to  which 
two  angle-irons  are  riveted, 
one  at  the  top  and  the  other 
at  the  bottom.  On  the 
lower  angle-iron  the  sheath- 
ing plates  d  are  riveted ;  and  on  the  upper,  interior  plates,  some 
Fig.  109.  of  which  in  large  vessels  are 

•wi  '  Vjoi  £^j i  riveted  diagonally,  so  as  to 

form  stringers  and  braces 

c  from  the  keelsons  round  the 

JL  JL  bilge   to  the  upper  decks. 

iT^  4r^  <  ~^.  These  ribs  are  placed  at  dis- 

d  "    tan  ces  of  about  fifteen  inches 

to  eighteen  inches  apart,  according  to  their  position  in  the  direc- 
tion of  the  length  of  the 
ship. 

Other  kinds  of  frames 
might  be  used  with  double 
angle-iron,  as  shown  at  e  e, 
in  the  annexed  sketch 


Fig.  no. 


LI  J  I  I 


(Fig.  110),  but  they  are  more  expensive;  and  from  the  increased 
complexity  of  construction,  the  extra  strength  obtained  does  not 
compensate  for  the  difference  of  cost.  Although  the  frames  shown 


APPLICATION   OF   IRON  TO   SHIP-BUILDING. 


171 


in  Fig.  109  have  come  into  general  use  as  the  most  effective  and 
easy  of  construction. 

KEELS. — This  part  of  the  vessel  requires  to  be  made  exceedingly 
strong  to  resist  the  pressure  or  violent  shocks  to  whidi  it  is  sub- 
jected, when  a  vessel  grounds.  It  is  made  in  various  ways, 
generally  with  a  false  keel,  which  is  riveted  on  below  the  ribs  by 
two  angle-irons.  The  false  keel  is  intended  to  receive  the  first 
shock  in  grounding ;  and  is  so  arranged  that  it  may  even  be  carried 
away  without  material  injury  to  the  true  keel.  Fig.  Ill  shows  a 
method  in  which  it  will  be  seen  that  the  sheathing-plates  a  a  are 
bent  downwards  so  as  to  grasp  the  side  of  the  keel,  which  consists 
of  a  massive  plate  of  iron ;  whilst  the  angle-iron  of  the  ribs  is  bent 
upwards  at  right  angles,  and  is  firmly  riveted  to  the  Vertical  keel 
plate. 

Fig.  111. 


Fig.  112. 


DECKS. — The  floorings    are  supported  upon  beams    extending 
from  one  side  of  the  vessel  to  the  other,  and  attached  at  either  end 
to  the  ribs  or  side  frames.     In  the  section,  Fig.  108,  the  two  upper 
decks  are  supported  upon  wooden  beams,  as  in  an  ordinary 
wooden  vessel ;  but  wrought-iron  beams  may  be  sub- 
stituted for  these  with  great  advantage,  as 
shown  at  g  g. 

These  deck-beams  have  been  made  of  vari- 
ous forms,  the  best  of  which  for  large  ves- 
sels is  probably  that  shown  in  Fig.  112, 
which  consists  of  angle  irons  riveted  to  the 
top  and  to  the  bottom  of  a  thin  vertical 
plate.  In  some  cases  a  vertical  plate,  with 
two  angle-irons  at  the  top  and  one  at  the  bottom,  is  used,  and  has 


172  THE  PRACTICAL   METAL- WORKER'S  ASSISTANT. 

the  advantage  of  greater  simplicity,  though  the  material  is  not  so 
well  distributed.  The  box  beam  (Fig.  113)  is  employed  for  sup- 
porting the  shafts  and  paddle-boxes  of  steamers,  etc. 

KiVETiNGfOF  THE  PLATES. — In  all'wrought-iron  constructions,  the 
mode  of  joining  two  plates  together  is  the  same.  When  the  article 
can  neither  be  produced  at  once  from  the  rolling-mill  nor  the 
steam-hammer,  and  except  in  the  comparatively  few  cases  where 
parts  are  welded  together,  they  are  universally  united  by  rivets.  A 
series  of  holes  being  made  through  both  pieces,  a  small  bolt,  with 
a  head  upon  one  side,  is  passed  through  each,  and  then  quickly 
hammered  down  on  the  other  side  to  another  head,  so  as  to  grasp 
the  parts  tightly  between  them.  These  rivets  are  usually  employed 
in  a  red-hot  state,  both  because  they  are  then  more  easily  ham- 
mered down,  and  because  in  cooling  they  contract  and  draw  the 
parts  together  with  great  force. 

Since  the  introduction  of  this  process,  the  greatest  improvement 
has  been  the  substitution  of  the  riveting-machine,  invented  by  Mr. 
Fairbairn ;  by  means  of  which  the  object  is  secured  in  consider- 
ably less  time  and  at  less  cost,  and  which  completes  the  union  of 
the  plates  with  much  greater  perfection  than  could  possibly  be 
done  by  the  hand.  But  this  new  and  very  superior  process  has  not 
as  yet  been  successfully  applied  to  the  riveting  of  plates  for  ships. 

On  comparing  the  strength  of  plates  with  their  riveted  joints,  it 
will  be  necessary  to  examine  the  sectional  areas  taken  in  a  line 
through  the  rivet-holes  with  the  section  of  the  plates  themselves. 
It  is  perfectly  obvious  that  in  perforating  a  line  of  holes  along  the 
edge  of  a  plate,  we  must  reduce  its  strength ;  it  is  also  clear  that 
the  plate  so  perforated  will  be  to  the  plate  itself,  nearly  as  the 
areas  of  their  respective  sections,  with  a  small  deduction  for  the 
irregularities  of  the  pressure  of  the  rivets  upon  the  plate ;  or,  in 
other  words,  the  joint  will  be  reduced  in  strertgth  somewhat  more 
than  in  the  ratio  of  its  section  through  that  line  to  the  solid  sec- 
tion of  the  plate.  For  example,  suppose  two  plates,  each  two  feet 
wide  and  three-eighths  of  an  inch  thick,  to  be  riveted  together  with 
ten  three-fourth  inch  rivets.  It  is  evident  that  out  of  two  feet,  the 
length  of  the  joint,  the  strength  of  the  plates  is  reduced  by  per- 
foration to  the  extent  of  seven  and  a  half  inches ;  and  here  the 
strength  of  the  plates  will  be  to  that  of  the  joint  as  9  :  6.187*, 
which  is  nearly  the  same  as  the  respective  areas  of  the  solid  plate 
and  that  through  the  rivet-holes ;  or  as  24  :  16'5f.  From  these 
facts  it  is  evident  that  the  rivets  cannot  add  to  the  strength  of  the 
plates,  their  object  being  to  keep  the  two  surfaces  of  the  lap  in 
contact.  It  may  be  said  that  the  pressure  or  adhesion  of  the  two 
surfaces  of  the  plates  would  add  to  the  strength ;  but  this  is  not 
found  to  be  the  case  to  any  great  extent,  as  in  almost  every  in- 
stance the  experiments  indicate  the  resistance  to  be  in  the  ratio  of 
their  sectional  areas. 

*  The  ratio  of  the  areas.          f  The  ratio  of  the  breadth  of  metal 


APPLICATION*   OF    IRON"   TO   SHIP-BUILDING.  173 

"When  this  great  deterioration  of  strength  at  the  joint  is  taken 

into  account,  it  cannot  but  be  of  the  greatest  importance  that  in 

structures  subjected  to  such  violent  strains  as  ships,  the  strongest 

method  of  riveting  should  be  adopted.     To  ascertain  this,  a  long 

series  of  experiments  were  undertaken  by  Mr. 

Fig.  114.  Fairbairn,  some  of  the  results  of  which  will  be 

/ .       of  interest  here.     The  joint  ordinarily  employed 

]_ 1      in  ship-building  is  the  lap- 

!oo  o  o o o olci  A  joint,  shown  in   Figs.  114  Flg>  115' 
(~  '    and  115.     The  plates  to  be 
J          united  are  made  to  overlap, 

and  the  rivets  are  passed 
through  them,  no  covering-plates  being  re- 
quired, except  at  the  ends  of  the  plate  where 
they  butt  against  each  other.  It  is  also  a  ^common  practice  to 
countersink  the  rivet-heads  on  the  exterior  of  the  vessel,  that  the 
hull  may  present  a  smooth  surface  for  her  passage  through  the 
water.  This  system  of  riveting  is  shown  in  Fig.  Ill,  where  the 
rivets  of  the  sheathing-plates  are  countersunk.  This  system  of 
riveting  is  only  used  when  smooth  surfaces  are  required ;  under 
other  circumstances  their  introduction  would  not  be  desirable,  as 
they  do  not  add  to  the  strength  of  the  joint,  but  to  a  certain  ex- 
tent reduce  it.  This  reduction  is  not  observable  in  the  experi- 
ments ;  but  the  simple  fact  of  sinking  the  head  of  the  rivet  into 
•  the  plate,  and  cutting  out  a  greater  portion  of  metal,  must  of  neces- 
sity lessen  its  strength,  and  render  it  weaker  than  the  plain  joint 
with  raised  heads. 

There  are  two  kinds  of  lap-joints,  those  said  to  be  single-riveted 
(Fig.  114)  and  those  which  are  double-riveted  (Fig.  115).  At  first 
the  former  were  almost  universally  employed,  but  the  greater 
strength  of  the  latter  has  since  led  to  their  general  adoption  in  the 
larger  descriptions  of  vessels.  The  reason  of  the  superiority  is 
evident.  A  riveted  joint  gives  way  either  by  shearing  off  the  rivets 
in  the  middle  of  their  length,  or  by  tearing  through  one  of  the 
plates  in  the  line  of  the  rivets.  In  a  perfect  joint  the  rivets  should 
be  on  the  point  of  shearing  just  as  the  plates  were  about  to  tear- 
but  iii  practice  the  rivets  are  usually  made  slightly  too  strong. 
Hence  it  is  an  established  rule  to  employ  a  certain  number  of  rivets 
per  lineal  foot.  If  these  are  placed  in  a  single  row,  the  rivet-holes 
so  nearly  approach  each  other  that  the  strength  of  the  plates  is 
much  reduced ;  but  if  they  are  arranged  in  two  lines,  a  greater 
number  may  be  used,  and  yet  more  space  left  between  the  holes, 
and  greater  strength  and  stiffness  imparted  to  the  plates  at  the 
joint. 


174 


THE    PRACTICAL   METAL-WORKER'S  ASSISTANT. 


The  results  of  Mr.  Fairbairn's  experiments  upon  the  two  forms 
of  joint  are  given  in  the  following  summary : 


Strength   of   single-riveted 

Strength  of  double-riveted 

Cohesive  strength 
of  plates. 

joints  of  equal  section  to 
the  plates,  taken  through 

joints  of  equal  section  to 
the  plates,  taken  through 

the  line  of  rivets. 

the  line  of  rivets. 

Ibs.  per  sq.  in. 

Breaking-weight  in  Ibs.  per 
sq.  in. 

Breaking-weight  in  Ibs.  per 
sq.  in. 

57,724 

45,743 

52,352 

61,579 

36,606 

48,821 

58,322 

43,141 

58,286 

50,983 

43,515 

54,594 

51,130 

40,249 

53,879 

49,281 

44,715 

53,879 

43,805 

37,161 

47,062  % 

Mean 

52,486 

41,590 

53,635 

The  relative  strengths  will  therefore  be — 

For  the  plate 1000 

Double-riveted  joint .     .     .     .   1021 
Single-riveted  joint  ....     791 

From  the  above  it  will  be  seen  that  the  single-riveted  joints  have 
lost  one-fifth  of  the  actual  strength  of  the  plates,  whilst  the  double- 
riveted  have  retained  their  resisting  powers  unimpaired.  These 
are  important  and  convincing  proofs  of  the  superior  value  of  the 
double  joint ;  and  in  all  cases  where  strength  is  required,  this  de- 
scription of  joint  should  invariably  be  used. 

Comparing  these  results  with  those  of  a  former  analysis,  we 
have — 


1000  :  1021  and  791* 
1000  :     933  and  731 


Mean 


1000  :    977  and  761 

which  in  practice  we  may  safely  assume  as  the  correct  value  of 
each.  Exclusive  of  this  difference,  we  must,  however,  deduct  thirty 
per  cent,  for  the  loss  of  metal  actually  punched  out  for  the  reception 
of  the  rivets ;  and  the  absolute  strength  of  the  plates  will  then  be, 
to  that  of  the  riveted  joints,  as  the  numbers  100,  68,  46.  In  some 
cases,  where  the  rivets  are  wider  apart,  the  loss  sustained  is,  how- 
ever, not  so  great ;  but  in  boilers  and  similar  vessels  where  the 
rivets  require  to  be  close  to  each  other,  the  edges  of  the  plates  are 
weakened  to  that  extent.  Taking  into  consideration  the  various 
circumstances  affecting  the  experimental  results,  we  may  fairly 

*The  cause  of  the  increase  of  strength  in  the  double-riveted  plates  may  be 
attributed  to  the  riveted  specimens  being  made  of  best  iron  ;  whereas  the 
mean  strength  of  the  plates  is  taken  from  all  the  irons  experimented  upon, 
some  of  inferior  quality,  which  will  account  for  the  high  value  of  the  double- 
riveted  joint. 


APPLICATION   OF   IRON   TO   SHIP-BUILDING. 


175 


assume  the  following  relative  strengths  as  the  value  of  plates  with 

their  riveted  joints. 

Taking  the  strength  of  the  plate  at 100 

The  strength  of  the  riveted  joint  would  then  be  .     70 
And  the  strength  of  the  single  riveted  joint     .     .     56 

WOOD  AND  IRON  AS  MATERIALS  FOR  SHIP-BUILDING. — We  shall 

consider  this  point  under  three  heads — 

STRENGTH, 

DURABILITY,  • 

ECONOMY. 

To  ascertain  the  superiority  of  iron  over  A^ood  in  regard  to 
strength,  let  us  consider  the  strains  to  which  a  vessel  is  subjected. 
Let  us  take,  for  example,  a  vessel  of  similar  dimensions  to  the 
"  Great  Western"  (the  first  steamer  that  successfully  crossed  the 
Atlantic),  212  feet  long  between  the  perpendiculars,  35  feet  beam, 
and  23  feet  from  the  surface  of  the  main  deck  to  the  bottom  of  the 
sheathing  attached  to  the  keel.  Now,  considering  a  vessel  of  this 

,       Fig.  116. 


magnitude,  with  its  machinery  and  cargo,  to  weigh  3000  tons,  in- 
cluding her  own  weight ;  and  supposing,  in  the  first  instance,  that 
she  is  suspended  upon  two  points,  A  and  B,  resting  on  the  bow 
and  stern,  at  a  distance  of  210  feet,  as  shown  in  Fig.  116 ;  we  should 
then  have  to  calculate,  from  some  formula  yet  to  be  determined  by 
experiment,  the  ultimate  strength  of  the  ship. 

To  determine  this  formula  with  accuracy  is  a  work  of  research. 
In  the  meantime,  we  are  fortunate  in  having  before  us  that  which 
applies  with  so  much  certainty  to  tubular  bridges  and  tubular 
girders ;  and  all  that  is  required  in  this  case  will  be  to  ascertain 
the  correct  sectional  area  of  the  plates,  to  prevent  the  tearing  asun- 
der of  the  bottom,  and  the  quantity  of  material  necessary  to  resist 
the  crushing  force,  along  the  line  of  the  upper-deck  on  the  top. 
It  is  true  that  the  necessary  data  have  yet  to  be  determined ;  but 
the  iron  ship-builder  cannot  be  far  yrong  if  he  assumes  the  weight 
W  in  the  middle  (Fig.  116)  to  be  equal  to  the  united  weights 
of  the  ship  and  cargo.  This,  in  the  case  before  us,  would  give 
an  ultimate  power  of  resistance  of  3000  tons  in  the  middle,  or 
6000  tons  equally  distributed  along  the  ship,  with  her  keel  down- 
wards. 

Assuming  these  tests,  or  the  calculation  derived  therefrom,  to 
be  correct,  let  us  now  bring  the  vessel  into  a  totally  different  po- 


176  THE   PRACTICAL    METAL-WOBKEK'S   ASSISTANT. 

sition,  as  in  Fig.  117,  having  the  same  weight  of  cargo  on  board, 
and  supported  by  a  wave,  which,  for  the  sake  of  illustration,  we 
mav  consider  as  supporting  the  vessel  upon  a  single  point  in  the 
middle. 

Fig.  117. 


In  this  position  we  find  the  strain  reversed ;  and  in  the  place 
of  the  lower  part  of  the  hull  of  a  ship  being  in  a  state  of  tension, 
it  is,  on  the  contrary,  in  a  state  of  compression,  and  the  whole  of 
those  parts  below  the  neutral  axis  are  subjected  to  that  strain.  On 
the  other  hand,  the  upper  part  is  in  a  state  of  tension ;  and  that 
tension,  as  well  as  the  compressive  strain  below,  will  be  found  to 
vary  in  degree  in  the  ratio  of  the  distances  from  the  centre  of  the 
neutral  axis  a  (Fig.  117),  round  which  the  forces  of  tension  and 
compression  revolve.  In  this  supposed  position  we  may  venture 
to  calculate  the  strengths,  in  order  to  ascertain  the  limit "  or  maxi- 
mum of  security,  and  act  as  if  the  vessel  were  placed  in  trying 
circumstances, — either  contending  with  the  rolling  seas  of  a  hur- 
ricane, or  suffering  the  actual  suspension  of  either  portion  when 
taking  the  ground.  In  these  critical  positions,  we  arrive  at  the 
conclusion,  that  calculations  founded  upon  the  formula  for  wrought- 
iron  tubular  beams  will  determine  the  strength  and  resisting  powers 
of  an  iron  ship,  and  that  under  every  contingency  and  every  cir- 
cumstance in  which  the  vessel  can  be  placed.  Moreover,  it  will 
give  a  wide  margin  of  security  under  all  those  forms  and  con- 
ditions of  peril  to  which  every  vessel  navigating  the  ocean  is 
exposed.  We  are  fully  aware  that  many  thousand  vessels  are  now 
afloat  that  would  not  stand  one-third  of  the  tests  which  we  have 
taken ;  but  that  is  no  reason  why  we  should  not  endeavor  to  effect 
more  judicious  distribution  of  the  material,  in  order  to  attain  the 
maximum  strength,  where  human  life  and  the  fortunes  of  the 
public  are  at  stake. 

To  show  that  we  have  not  selected  tests  which  no  vessel  would 
stand,  we  append  the  following  incidents : 

In  hauling  an  iron  steamer  of  nearly  400  tons  burthen  out  of.  a 
temporary  basin,  she  grounded  on  the  extreme  end  of  the  bank, 
and  was  left,  as  the  tide  receded,  with  forty  feet  of  her  stern  en- 
tirely without  support,  and  her  bow  buried  in  the  opposite  bank. 
On  the  return  of  the  tide,  the  vessel  floated,  and  immediately  after- 
wards she  proceeded  on  her  voyage. 

A  large  steamer,  the  "  Vanguard,"  ran  foul  of  a  reef  of  rocks  on 
the  west  coast  of  Ireland,  and  continued  exposed  to  the  swell  of 
the  Atlantic  beating  her  upon  them  for  several  days,  with  com- 


APPLICATION   OF   IRON   TO   SHIP-BUILDING.  177 

paratively  little  injury,  excepting  only  the  corrugation  of  the 
plates  along  her  bottom.  She  appears  to  have  rested  upon  a 
number  of  small  hard  rocks  from  the  stem  to  the  full  part  of  the 
vessel  just  under  the  paddle-wheels,  and  from  that  part  to  the  stern 
to  have  been  quite  unsupported,  except  at  one  place  where  the 
keel  was  broken.  Mr.  Clark,  who  went  to  examine  her,  states  that 
"  although  she  was  beating  hard  for  so  many  days,  no  part  of  her 
engines  was  deranged.  Her  engines  were  kept  constantly  at  work, 
ana,  in  his  opinion,  are  now  in  as  permanent  working  order  as  ever 
they  were.  Had  the  '  Vanguard'  been  built  of  wood  instead  of 
iron,  she  could  not  have  been  saved." 

"  The  '  Eoyal  George,'  one  of  the  iron  steamers  running  between 
Liverpool  and  Glasgow — a  vessel  of  unusual  length  in  proportion 
to  her  beam — got  on  a  rock  near  Greenock  at  high  water,  when 
loaded  with  about  150  tons  of  dead  weight  besides  her  engines  and 
coals,  and  was  left  there  high  and  dry  during  a  whole  tide  without 
sustaining  any  injury.  She  rested  nearly  on  her  centre ;  and  all 
who  saw  her  were  of  opinion  that  no  timber  vessel  could  have  re- 
mained in  that  position  without  breaking  her  back."  * 

We  might  adduce  numerous  other  instances  in  which  iron  ves- 
sels have,  without  material  injury,  stood  the  strains  which  must 
have  caused  a  timber  vessel  to  go  to  pieces.  An  iron  ship  is 
united  by  riveting  into  a  single  firm  mass ;  whilst  a  wooden  vessel 
is  composed  of  an  innumerable  number  of  pieces,  all  imperfectly 
joined '  together,  but  which  are,  nevertheless,  dependent  on  each 
other  for  support, — so  that  if  any  one  gives  way,  the  stability  of 
all  the  rest  is  endangered. 

In  his  paper  on  iron  as  a  material  for  ship-building,  Mr.  Fair- 
bairn  gives  the  following  results  of  some  experiments  on  the  com- 
parative strength  of  wood  and  iron,  when  subjected  to  pressure 
from  a  blunt  instrument  placed  at  right  angles  to  the  surface  of 
the  plate.  It  will  be  seen  that,  in  these  experiments,  an  endeavor 
was  made  to  place  the  material  in  circumstances  similar  to  those 
mentioned  above,  where  the  vessel  is  beating  upon  hard  and  unequal 
ground.  In  these  experiments,  the  wrought-iron  plates  were  fastened 
upon  a  frame  of  cast-iron,  one  foot  square  inside,  and  one  foot  six 
inches  outside.  The  sides  of  the  plate,  when  hot,  were  twisted 
round  the  frame,  to  which  they  were  firmly  bolted.  The  force  to 
burst  it  was  applied  in  the  centre  by  a  bolt  of  iron,  terminating  in 
a  hemisphere  three  inches  in  diameter. 

Summary  of  Results. 

Ibs.          Mean  :  Ibs. 
In  Experiment  I.,  a  plate  one-fourth  of  an  inch 

thick  was  burst  by 13,789  ) 

In  Experiment  II.,  a  plate  one-fourth  of  an  inch  >      16,779 

thick  was  burst  by 19,769  ) 

*  Grantham  "  On  Iron  as  a  Material  for  Ship-Building." 
12 


178  THE  PRACTICAL  METAL-WORKER'S  ASSISTANT. 

Ibs.  Mean  :  Ibs. 
In  Experiment  III.,  a  plate  half  an  inch  thick  1 

was  burst  by 37,519  I  ^  ^3 

In  Experiment  IV.,  a  plate  half  an  inch  thick 

was  burst  by     .    .    ..«..*••.. ,U,*wy^.*    .  37,928 J 

Here  the  strengths  are  as  the  depths,  a  half-inch  plate  requiring 
double  the  weight  to  produce  fracture  that  had  previously  burst  a 
quarter-inch  plate. 

The  experiments  on  wood  were  made  upon  good  English  oak,  of 
the  same  width  as  the  iron  plates.  The  specimens  were  laid  upon 
solid  planks  twelve  inches  asunder,  and  by  the  same  apparatus  the 
rounded  end  of  the  three-inch  pin  was  forced  through  them. 

Summary  of  Results. 

Ibs.         Mean  :  Ibs. 

Strength  of  planks  3  inches  thick 18,941  ) 

3       «        "  16,925  f 

1J      "        "  4,532  ) 

"  «       l|      "        "  4,280  J 


Here  the  strength  to  resist  crushing  follows  the  ratio  of  the  square 
of  the  depth,  as  is  found  to  be  the  case  in  the  transverse  fracture  of 
rectangular  bodies  of  constant  breadth  and  span.  The  experiments 
show  conclusively  the  superiority  of  iron  in  ordinary  cases. 

DURABILITY. — The  durability  of  iron  ships  is  now  established 
beyond  a  doubt;  and  it  is  generally  admitted  that  they  remain  fit 
for  service  longer  than  those  of  timber.  At  first  it  was  thought 
that  the  action  of  salt-water  would  cause  a  rapid  oxidation,  and  very 
soon  disable  them ;  indeed,  oxidation  has  been  the  rock-ahead  of 
every  iron  ship  for  the  last  twenty  years.  The  evil  has  been  ex- 
aggerated ;  and  there  are  instances  of  iron  ships  built  twenty  years 
ago,  which  are  still  in  existence  with  no  sensible  appearance  of  cor- 
rosion or  decay,  and,  what  is  of  equal  importance,  without  having 
required  repairs,  if  we  except  a  few  coats  of  oil-paint,  or  the  appli- 
cation of  some  other  anti-corrosive  substance  to  neutralize  the 
effects  of  the  sea- water.  Nature,  however,  comes  to  our  assistance 
in  this,  as  in  almost  every  other  attempt  in  the  constructive  arts, 
and  seems  to  confirm  the  proverb,  "A  bright  sword  never  rusts ;" 
for  it  is  with  iron  ships  as  with  iron  rails — when  in  constant  use 
there  is  little,  if  any,  appearance  of  oxidation. 

ECONOMY. — Mr.  Grantham,  in  the  work  already  quoted,  comes 
to  the  conclusion  that  iron  vessels  are  on  the  whole  less  expensive 
in  construction  than  similar  vessels  of  wood.  But  assuming  that, 
when  built  in  the  best  manner,  they  cost  about  the  same,  still,  the 
iron  ship  has  great  advantages.  The  strength  of  iron  is  so  great 
that  we  are  enabled  to  use  a  much  thinner  shell  than  with  wood ; 
and  hence  there  is  much  more  stowage  room.  The  cost  of  main- 
taining an  iron  vessel,  repairs,  etc.,  are  very  small ;  whilst  in  a  tim- 


METALS  AND  ALLOYS.  179 

her  vessel  they  amount  to  a  large  sum.  Iron  vessels  are  not  sub- 
ject to  a  dry  rot ;  and  we  have  already  seen  that  they  will  remain 
under  severe  strain  comparatively  uninjured,  when  a  timber  vessel 
would  go  to  pieces. 

It  is  necessary  here  to  advert  to  the  use  of  iron  as  applied  to 
vessels  of  war.  There  cannot  exist  a  doubt  as  to  the  advantages  to 
be  derived  from  iron  as  a  material  for  ship-building,  and  it  is  as 
desirable  in  the  navy  as  in  the  merchant  service ;  but  the  great  draw- 
back to  its  application  is  the  effect  of  shot  upon  iron  plates,  and  the 
consequent  danger  to  the  vessel  if  not  regularly  "  armored,"  but  merely 
constructed  of  iron  like  a  merchantman.  This  danger  does  not  arise 
so  much  from  point-blank  shot  entering  the  ship  at  high  velocities, 
as  from  shot  ranging  from  a  distance,  and  which  strike  the  vessel 
with  a  reduced  force.  In  the  first  case  the  shot  penetrates  and 
passes  through  the  plates,  making  a  perforation  equal  in  diameter 
to  the  shot ;  but  a  half-spent  shot  when  it  arrives,  not  only  pene- 
trates the  side  of  the  ship,  but  tears  up  the  plates  to  a  distance  of 
some  feet  on  every  side.  It  is  from  this  that  the  chief  danger  is  to 
be  apprehended.  It  is  useless  here  to  point  out  that  which  is  now 
so  very  apparent  to  all  well  informed  persons,  that  the  successful 
application  of  iron  in  the  building  of  powerful  vessels  of  war,  dur- 
ing the  present  contest  in  the  United  States — eventful  in  so  very 
many  respects — has  opened  a  new  era  in  ocean  warfare.  So  great 
is  this  revolution,  that  the  navies  of  the  old  world  are  now  rendered 
comparatively  harmless  and  consequently  useless ;  and  the  United 
States,  with  her  "New  Ironsides,"  "Dunderberg,"  "Dictator,"  "Puri- 
tan," "  Roanoke,"  and  other  iron-clads,  is  to-day  not  only  the  first 
military,  but  the  first  naval  power  in  the  world. 


CHAPTER  XII. 

THE  METALS  AND  ALLOYS  MOST  COMMONLY  USED. 

WE  have  now  to  consider  the  following  metals :  Antimony,  Bis- 
muth, Copper,  Gold,  Lead,  Mercury,  Nickel,  Palladium,  Platinum, 
Rhodium,  Silver,  Tin,  and  Zinc.  Unlike  iron  and  steel,  they  do 
not  admit  of  being  hardened  beyond  that  degree  which  may  be 
produced  by  simple  mechanical  means,  such  as  hammering,  rolling, 
etc.,  neither  (with  the  exception  of  platinum)  do  they  submit  to 
the  process  of  welding. 

On  the  other  hand,  their  fusibility  offers  an  easy  means  of  unit- 
ing and  combining  many  of  these  metals  with  great  readiness, 
either  singly,  or  in  mixtures  of  two  or  several  kinds,  which  are 
called  alloys.  By  the  process  of  founding,  any  required  form  may 


180  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

be  given  to  the  fusible  metals  and  alloys  :  their  malleability  and 
ductility  are  also  turned  to  most  useful  and  varied  account ;  and 
by  partial  fusion  neighboring  metallic  surfaces  may  be  united, 
sometimes  per  se,  but  more  generally  by  the  interposition  of  a  still 
more  fusible  metal  or  alloy  called  solder. 

The  author  intends  therefore  to  commence  with  a  brief  notice  of 
the  physical  characters  and  principal  uses  of  the  thirteen  metals 
before  named,  and  of  their  more  important  alloys.  Tables  of  the 
cohesive  force  and  of  the  general  properties  of  metals  will  be  next 
added  to  avoid  the  occasional  necessity  for  reference  to  other 
works. 

These  tables  will  be  followed  by  some  remarks  on  alloys,  which  as 
regards  their  utility  in  the  arts,  may  be  almost  considered  as  so 
many  distinct  metals ;  this  will  naturally  lead  to  the  processes  of 
melting,  mixing  and  casting  the  metals  ;  a  general  notice  and  ex- 
planation of  many  works,  taking  their  origin  in  the  malleable  and 
ductile  properties,  will  then  follow ;  and  the  consideration  of  the 
metals,  and  of  materials  from  the  three  kingdoms,  will  be  con- 
cluded by  a  descriptive  account  of  the  modes  of  soldering. 


DESCRIPTION 

OF  THIS 

PHYSICAL  CHARACTER  AND  USES 

OF 

THE  METALS  AND  ALLOYS 

COMMONLY  EMPLOYED  IN 

THE  MECHANICAL  AND  USEFUL  ARTS. 


ANTIMONY  is  of  a  silvery  white  color,  brittle  and  crystalline  in 
its  ordinary  texture.  It  fuses  at  about  800°,  or  at  a  dull 
red  heat,  and  is  volatile  at  a  white  heat.  Its  specific  gravity 
is  6.712. 

ANTIMONY  expands  on  cooling ;  it  is  scarcely  used  alone, 
except  in  combination  with  similar  bars  of  other  metals  for 
producing  thermo-electricity :  but  antimony,  which  in  the 
metallic  state  is  frequently  called  "  regulus,"  is  generally 
combined  with  a  large  portion  of  lead,  and  sometimes  with 
tin,  and  other  metals.  See  LEAD  and  TIN. 

"Antimony  and  tin,  mixed  in  equal  proportions,  form  a 
moderately  hard,  brittle,  and  very  brilliant  alloy,  capable  of 
receiving  an  exquisite  polish,  and  not  easily  tarnished  by 
exposure  to  the  air  ;  it  has  been  occasionally  manufactured 
into  speculums  for  telescopes.  Its  s.  g.  is  less  than  the 
mean  of  its  constituent  parts." 


METALS  AND  ALLOYS.  181 

BISMUTH  is  a  brittle  white  metal  with  a  slight  tint  of  red  :  its 
specific  gravity  is  9.822.  It  fuses  at  476°  to  507°,  and 
always  crystallizes  on  cooling.  According  to  Chaudet,  pure 
bismuth  is  somewhat  flexible.  A  cast  bar  of  the  metal, 
one-tenth  of  an  inch  diameter,  supports,  according  to  Mus- 
chenbroeck,  a  weight  of  forty-eight-pounds.  Bismuth  is 
volatile  at  a  high  heat,  may  be  distilled  in  close  vessels.  It 
»  transmits  heat  more  slowly  than  most  other  metals,  perhaps 
in  consequence  of  its  texture. 

BISMUTH  is  scarcely  used  alone,  but  it  is  employed  for 
imparting  fusibility  to  alloys,  thus: 

8  bismuth,  5  lead,  3  tin,  constitute  a  fusible  alloy,  which 
melts  at  212°  F. 

2  bismuth,  1  lead,  1  tin,  a  fusible  alloy,  which  melts  at 
201°  F. 

5  bismuth,  3  lead,  2  tin,  when  combined  melt  at  199°. 

8  bismuth,  5  lead,  4  tin,  1  type  metal,  constitute  the  fusi- 
ble alloy  used  on  the  Continent  for  producing  the  beautiful 
casts  of  the  French  medals,  by  the  clicJiee  process.  The 
metals  should  be  repeatedly  melted  and  poured  into  drops 
until  they  are  well  mixed. 

1  bismuth,  and  2  tin,  make  an  alloy  found  to  be  the  most 
suitable  for  rose-engine  and  eccentric-turned  patterns,  to  be 
printed  from  after  the  manner  of  letter-press.  The  thin 
plates  are  cast  upon  a  cold  surface  of  metal  or  stone,  upon 
which  a  piece  of  smooth  paper  is  placed,  and  then  a  metal 
ring  ;  the  alloy  should  neither  burr  nor  crumble  ;  if  proper, 
it  turns  soft  and  silky  ;  when  too  crystalline,  more  tin  should 
be  added. 


All  these  alloys  must  be  cooled  quickly  to  avoid  the  sep- 
aration of  the  bismuth  ;  they  are  rendered  more  fusible  by 
a  small  addition  of  mercury. 

COPPER,  with  the  exception  of  titanium,  is  the  only  metal  which 
has  a  red  color  ;  it  has  much  lustre,  is  very  malleable  and 
ductile,  and  exhales  a  peculiar  smell  when  warmed  or  rub- 
bed. It  melts  at  a  bright-red  or  dull  white  heat  at  a  tem- 
perature intermediate  between  the  fusing  points  of  silver  and 
gold=1996°  Fahr.  Its  specific  gravity  varies  from  8.86  to 
8.89  ;  the  former  being  the  least  density  of  cast  copper,  the 
latter  the  greatest  of  rolled  or  hammered  copper. 

COPPER  is  used  alone  for  many  important  purposes,  and 
very  extensively  for  the  following  :  namely,  sheathing  and 
bolts  for  ships,  brewing,  distilling,  and  culinary  vessels. 
Some  of  the  fire  J>oxes  for  locomotive  engines,  boilers  for 
marine  engines,  rollers  for  calico-printing  and  paper-mak- 
ing, plates  for  the  use  of  engravers,  etc. 


182  THE   PKACTICAL   METAL-WORKER'S   ASSISTANT. 

Copper  is  used  in  alloying  gold  and  silver,  for  coin,  plate, 
etc.,  and  it  enters  with  zinc  and  nickel  into  the  composition 
of  German  silver.  Copper  alloyed  with  one-tenth  of  its 
weight  of  arsenic  is  so  similar  in  appearance  to  silver,  as  to 
have  been  substituted  for  it. 

The  alloys  of  copper,  which  are  very  numerous  and  im- 
portant, are  principally  included  under  the  general  name, 
Brass.  In  the  more  common  acceptation,  brass  means  the 
yellow  alloy  of  copper,  with  about  half  its  weight  of  zinc  ; 
this  is  often  called  by  engineers  "  yellow  brass." 

Copper  alloyed  with  about  one-ninth  its  weight  of  tin,  is 
the  metal  of  brass  ordnance,  which  is  very  generally  called 
gun-metal ;  similar  alloys  used  for  the  "  brasses"  or  bearings 
of  machinery,  are  called  by  engineers,  hard  brass,  and  also 
gun- metal ;  and  such  alloys  when  employed  for  statues  and 
medals  are  called  bronze.  The  further  addition  of  tin  leads 
to  bell  metal,  and  speculum  metal,  which  are  named  after 
their  respective  uses ;  and  when  the  proportion  of  copper  is 
exceedingly  small  the  alloy  constitutes  one  kind  of  pewter. 

Copper,  when  alloyed  with  nearly  half  its  weight  of  lead, 
forms  an  inferior  alloy,  resembling  gun-metal  in  color,  but 
very  much  softer  and  cheaper,  lead  being  only  about  one- 
fourth  the  value  of  tin,  and  used  in  much  larger  propor- 
tion. 

This  inferior  alloy  is  called  pot-metal,  and  also  cock- 
metal,  because  it  is  used  for  large  vessels  and  measures,  for 
the  large  taps  or  cocks  for  brewers,  dyers  and  distillers,  and 
those  of  smaller  kinds  for  household  use. 

Generally,  the  copper  is  only  alloyed  with  one  of  the 
metals,  zinc,  tin,  or  lead ;  occasionally  with  two,  and  some- 
times with  the  three  in  various  proportions.  In  many  cases, 
the  new  metals  are  carefully  weighed  according  to  the  quali- 
ties desired  in  the  alloy,  but  random  mixtures  more  fre- 
quently occur,  from  the  ordinary  practice  of  filling  the 
crucible  in  great  part  with  various  pieces  of  old  metal,  of 
unknown  proportions,  and  adding  a  certain  quantity  of  new 
metal  to  bring  it  up  to  the  color  and  hardness  required. 
This  is  not  done  solely  from  motives  of  economy,  but  also 
from  an  impression  which  appears  to  be  very  generally 
entertained,  that  such  mixtures  are  more  homogeneous  than 
those  composed  entirely  of  new  metals,  fused  together  for 
the  first  time. 

The  remarks  I  have  to  offer  on  these  copper  alloys  will 
be  arranged  in  the  tabular  form,  in  four  groups ;  and  to 
make  them  as  practical  as  possible,  they  will  be  stated  in 
the  terms  commonly  used  in  the  brass-foundry.  Thus, 
when  the  founder  is  asked  the  usual  proportions  of  yellow 
brass,  he  will  say,  6  to  8  oz.  of  zinc  (to  every  pound  of 
copper  being  implied).  In  speaking  of  gun-metal,  he 


METALS  AXD  ALLOYS.  183 

wou  d  not  say,  it  had  one-ninth,  or  11  per  cent,  of  tin,  but 
simply  that  it  was  1J,  2,  or  2J  oz.  (of  tin),  as  the  case  might 
be  ;  so  that  the  quantity  and  kind  of  the  alloy,  or  the  addi- 
tion to  the  pound  of  copper,  is  usually  alone  named :  and 
to  associate  the  various  ways  of  stating  these  proportions, 
many  are  transcribed  in  the  forms  in  which  they  are  else- 
where designated. 

ALLOYS  OF  COPPER  AXD  Zixc  ONLY. 

The  marginal  numbers  denote  the  ounces  of  zinc  added  to  every  pound  of  copper. 

£  to  %  oz.  Castings  are  seldom  made  of  pure  copper,  as  under 
ordinary  circumstances  it  does  not  cast  soundly ;  about  half 
an  ounce  of  zinc  is  usually  added,  frequently  in  the  shape 
of  4  oz.  of  brass  to  every  pound  of  copper ;  and  by  others 
4  oz.  of  brass  are  added  to  every  two  or  three  pounds  of 
copper. 

1  to  1 J  oz.  Gilding  metal,  for  common  jewelry :  it  is  made  by 
mixing  4  parts  of  copper  with  1  of  calamine  brass ;  or 
sometimes  1  Ib.  of  copper  with  6  oz.  of  brass.  The  sheet 
gilding-metal  will  be  found  to  match  pretty  well  in  color 
with  the  cast  gun-metal,  which  latter  does  not  admit  of 
being  rolled ;  they  may  be  therefore  used  together  when 
required. 

3  oz.  Eed  sheet  brass,  made  at  Hegermiihl,  or  5|  parts  copper, 
1  zinc. 

3  to  4  oz.  Bath  metal,  pinchbeck,  Mannheim  gold,  similor,  and 
alloys  bearing  various  names,  and  resembling  inferior  jewel- 
er's gold  greatly  alloyed  with  copper,  are  of  about  this  pro- 
portion :  some  of  them  contain  a  little  tin ;  now,  however, 
they  are  scarcely  used. 

6  oz.        Brass,  that  bears  soldering  well. 

6  oz.         Bristol  brass  is  said  to  be  of  this  proportion. 

8  oz.  Ordinary  brass,  the  general  proportion ;  less  fit  for  solder- 
ing than  6  oz.,  it  being  more  fusible. 

8  oz.         Is  generally  the  ingot  brass,  made  by  simple  fusion  of  the 

two  metals. 

9  oz.         This  proportion  is  the  one  extreme  of  Muntz's  patent 

sheathing.     See  10§. 

lOf  oz.  Muntz's  metal,  or  40  zinc  and  60  copper.  "Any  propor- 
tions," says  the  patentee,  "between  the  extremes,  50  zinc 
and  50  copper,  and  37  zinc  63  copper,  will  roll  and  work  at 
the  red-heat ;"  but  the  first-named  proportion,  or  40  zinc  to 
60  copper  is  preferred. 

The  metal  is  cast  into  ingots,  heated  to  a  red-heat,  and 
rolled  and  worked  at  that  heat  into  ships'  bolts  and  other 
fastenings  and  sheathing. 

12  oz.  Spelter-solder  for  copper  and  iron  is  sometimes  made  in 
this  proportion ;  for  brass  work,  the  metals  are  generally 
mixed  in  equal  parts.  See  16  oz. 


184  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

12  oz.  Pale  yellow  metal,  fit  for  dipping  in  acids,  is  often  made 
in  this  proportion. 

16  oz.  Soft  spelter-solder,  suitable  for  ordinary  brass  work,  is 
made  of  equal  parts  of  copper  and  zinc.  About  14  Ibs.  of 
each  are  melted  together  and  poured  into  an  ingot  mould 
with  cross  ribs,  which  indents  it  into  little  squares  of  about 
2  Ibs.  weight ;  much  of  the  zinc  is  lost.  These  lumps  are 
afterwards  heated  nearly  to  redness  upon  a  charcoal  fire, 
and  are  broken  up  one  at  a  time  with  great  rapidity  on  an 
anvil  or  in  an  iron  pestle  and  mortar.  The  heat  is  a  critical 
point ;  if  too  great,  the  solder  is  beaten  into  a  cake  or  coarse 
lumps  and  becomes  tarnished ;  when  the  heat  is  proper,  it  is 
nicely  granulated,  and  remains  of  a  bright  yellow  color ;  it 
is  afterwards  passed  through  a  sieve.  Of  course  the  ultimate 
proportion  is  less  than  16  oz.  of  zinc. 

16  oz.  Equal  parts  is  the  one  extreme  of  Muntz's  patent  sheath- 
ing. SeelOf. 

16  J  oz.  Mosaic  gold,  which  is  dark-colored  when  first  cast,  but  on 
dipping  assumes  a  beautiful  golden  tint.  When  cooled  and 
broken,  all  yellowness  must  cease,  and  the  tinge  vary  from 
reddish  fawn  or  salmon  color,  to  a  light  purple  or  lilac,  and 
from  that  to  whiteness.  The  proportions  are  stated  as  from 
52  to  58  zinc  to  50  of  copper,  or  16 £  to  17  oz.  to  the  pound. 

32  oz.  or  2  zinc  to  1  copper,  a  bluish-white,  brittle  alloy,  very 
brilliant,  and  so  crystalline  that  it  may  be  pounded  cold  in  a 
mortar. 

128  oz.  or  two  ounces  of  copper  to  every  pound  of  zinc ;  a  hard 
crystalline  metal  differing  but  little  from  zinc,  but  more  tena- 
cious ;  it  has  been  used  for  laps  or  polishing  disks. 

EEMARKS  ON  THE  ALLOYS  OF  COPPER  AND  ZINC. 

These  metals  seem  to  mix  in  all  proportions. 

The  addition  of  zinc  continually  increases  the  fusibility, 
but  from  the  extremely  volatile  nature  of  zinc,  these  alloys 
cannot  be  arrived  at  with  very  strict  regard  to  proportion. 

The  red  color  of  copper  slides  into  that  of  yellow  brass  at 
about  4  or  5  oz.  to  the  pound,  and  remains  little  altered 
unto  about  8  or  10  oz. ;  after  this  it  becomes  whiter,  and 
when  32  oz.  of  zinc  are  added  to  16  of  copper,  the  mixture 
has  the  brilliant  silvery  color  of  speculum  metal,  but  with  a 
bluish  tint. 

These  alloys,  from  about  8  to  16  oz.  to  the  pound  of 
copper,  are  extensively  used  for  dipping,  as  in  an  enormous 
variety  of  furniture  work ;  in  all  cases  the  metal  is  annealed 
before  the  application  of  the  scouring  or  cleaning  processes, 
and  of  the  acids,  bronzes  and  lackers  subsequently  used. 

The  alloys  with  zinc  retain  their  malleability  and  ductility 
well,  unto  about  8  or  10  ounces  to  the  pound ;  after  this,  the 
crystalline  character  slowly  begins  to  prevail.  The  alloy  of 


METALS  AND  ALLOYS.  185 

2  zinc  and  1  copper,  before  named,  may  be  crumbled  in  a 
mortar  when  cold. 

The  ordinary  range  of  good  yellow  brass,  that  files  and 
turns  well,  is  from  about  4|  to  9  oz.  to  the  pound.  With 
additional  zinc,  it  is  harder  and  more  crystalline ;  with  less, 
more  tenacious,  and  it  hangs  to  the  file  like  copper ;  the 
range  is  wide,  and  small  differences  are  not  perceived. 

ALLOYS  OF  COPPER  AND  TIN  ONLY. 

The  marginal  numbers  denote  the  ounces  of  tin  added  to  every  pound  of  copper. 
Ancient  Copper  and  Tin  Alloys. 

f  oz.        Ancient  bronze  nails,  flexible,  or  20  copper,  1  tin. 

f  According  to  Pliny,  as  quoted 
If  oz.       Soft  bronze,  or  ..  9  to  1     by  Wilkinson. 

Ancient  weapons  and  tools, 

2  oz.        Medium  bronze,  or  8  to  1 J  by  various  analyses,  or  8  to  15 

per  cent,  tin ;  metals  from  8  to 


2£  oz.      Hard  bronze,  or  .  7  to  1 
6  to  8  oz.  Ancient  mirrors. 


12  per  cent,  tin,  with  two  parts 
zinc  added  to  each  100,  for 
improving  the  bronze  color. 


Modern  Copper  and  Tin  Alloys. 

1  oz.         Soft  gun  metal,  that  bears  drifting,  or  stretching  from  a 

perforation. 

1 J  oz.  A  little  harder  alloy,  fit  for  mathematical  instruments  ;  or 
12  copper  and  1  very  pure  grain  tin. 

1 J  oz.       Still  harder,  fit  for  wheels  to  be  cut  with  teeth. 

1£  to  2  oz.  Brass  ordnance,  or  8  to  12  per  cent,  tin ;  but  the  gen- 
eral proportion  is  one-ninth  part  of  tin. 

2  oz.         Hard  bearings  for  machinery. 

2£  oz.  Very  hard  bearings  for  machinery.  By  Muschenbroek's 
Tables  it  appears  that  the  proportion  1  tin  and  6  copper  is 
the  most  tenacious  alloy ;  it  is  too  brittle  for  general  use, 
and  contains  2£  oz.  to  the  pound  of  copper. 

3  oz.         Soft  musical  bells. 

3 1  oz.  Chinese  gongs  and  cymbals,  or  20  per  cent.  tin. 

4  oz.  House  bells. 
4J  oz.  Large  bells. 

5  oz.  Largest  bells. 

7£  to  8J  oz.  Speculum  metal.  Sometimes  one  ounce  of  brass  is 
added  to  every  pound  as  the  means  of  introducing  a  trifling 
quantity  of  zinc,  at  other  times  small  proportions  of  silver 
are  added;  the  employment  of  arsenic  is  by  some  recom- 
mended. 

The  object  agreed  upon  by  all  experimentalists  appears 
to  be  the  exact  saturation  of  the  copper  with  the  tin,  and 
the  proportionate  quantities  differ  very  materially  (in  this 


186  THE   PRACTICAL   METAL-WORKEE'S  ASSISTANT. 

and  all  other  alloys),  according  to  the  respective  degrees  of  purity 
of  the  metals :  for  the  most  perfect  alloys  to  this  group, 
Swedish  copper,  and  grain  tin,  should  be  used. 

When  the  copper  is  in  excess,  it  imparts  a  red  tint  easily 
detected ;  when  the  tin  is  in  excess,  the  fracture  is  granu- 
lated and  also  less  white.  The  practice  is  to  pour  the 
melted  tin  into  the  fluid  copper  when  it  is  at  the  lowest 
temperature  that  a  mixture  by  stirring  can  be  effected,  then 
to  pour  the  mixture  into  an  ingot  and  to  complete  the  com- 
bination by  remelting  in  the  most  gradual  manner,  by  put- 
ting the  metal  into  the  furnace  as  soon  almost  as  the  fire  is 
lighted :  trial  is  made  of  a  little  piece  taken  from  the  pot 
immediately  prior  to  pouring. 

82  oz.  of  tin  to  one  pound  of  copper,  makes  the  alloy  called  by 
the  pewterers  "  temper"  which  is  added  in  small  quantities 
to  tin,  for  some  kinds  of  pewter,  called  "  tin  and  temper,1"1  in 
which  the  copper  is  much  less  than  1  per  cent. 

EEMARKS  ON  THE  ALLOYS  OF  COPPER  AND  TIN  ONLY. 

These  metals  seem  to  mix  in  all  proportions. 

The  addition  of  tin  continually  increases  the  fusibility, 
although  when  it  is  added  cold  it  is  apt  to  make  the  copper 
pasty,  or  even  to  set  in  a  solid  lump  in  the  crucible. 

The  red  color  of  the  copper  is  not  greatly  impaired  in 
those  proportions  used  by  the  engineer,  namely,  up  to  about 
2 1  ounces  to  the  pound;  it  becomes  grayish  white  at  6,  the 
limit  suitable  for  bells,  and  quite  white  at  about  8,  the 
speculum  metal ;  after  this,  the  alloy  becomes  of  a  bluish 
cast. 

The  tin  alloy  is  scarcely  malleable  at  2  ounces,  and  soon 
becomes  very  hard,  brittle,  and  sonorous  ;  and  when  it  has 
ceased  to  serve  for  producing  sound,  it  is  employed  for 
reflecting  light. 

The  tough  tenacious  character  of  copper  under  the  tools 
rapidly  gives  way  ;  alloys  of  1 J  cut  easily,  2  J  assume  about 
the  maximum  hardness  without  being  crystalline  ;  after  this 
they  yield  to  the  file  by  crumbling  in  fragments  rather  than 
by  ordinary  abrasion  in  shreds,  until  the  tin  very  greatly 
predominates,  as  in  the  pewters,  when  the  alloys  become  the 
more  flexible,  soft,  malleable,  and  ductile,  the  less  copper 
they  contain. 

ALLOYS  OF  COPPER  AND  LEAD  ONLY. 

The  marginal  numbers  denote  the  ounces  of  lead  added  to  every  pound  of  copper. 

2  oz.         A  red-colored  and  ductile  alloy. 

4  oz.         Less  red  and  ductile  ;  neither  of  these  is  so  much  used  as 

the  following,  as  the  object  is  to  employ  as  much  lead  as 

possible 


METALS  AND  ALLOYS.  187 

6  oz.         Ordinary  pot-metal,  called  dry  pot-metal,  as  this  quantity 

of  lead  will  be  taken  up  without  separating  on  cooling ;  this 
is  brittle  when  warmed. 

7  oz.         This  alloy  is  rather  short,  or  disposed  to  break. 

8  oz.         Inferior  pot-rnetal,  called  wet  pot-metal,  as  the  lead  partly 

oozes  out  in  cooling,  especially  when  the  new  metals  are 
mixed ;  it  is  therefore  always  usual  to  fill  the  crucible  in 
part  with  old  metal,  and  to  add  new  for  the  remainder.  This 
alloy  is  very  brittle  when  slightly  warmed.  More  lead  can 
scarcely  be  used,  as  it  separates  on  cooling. 

EEMARKS  ON  THE  ALLOTS  OF  COPPER  AND  LEAD  ONLY. 

These  metals  mix  in  all  proportions  until  the  lead  amounts 
to  nearly  half,  after  this  they  separate  in  cooling. 

The  addition  of  lead  greatly  increases  the  fusibility. 

The  red  color  of  copper  is  soon  deadened  by  the  lead ; 
at  about  4  ounces  to  the  pound  the  work  has  a  bluish  leaden 
hue  when  first  turned,  but  changes  in  an  hour  or  so  to  that 
of  a  dull  gun-metal  character. 

When  the  lead  does  not  exceed  about  4  oz.  the  mixture 
is  tolerably  malleable,  but  with  more  lead  it  soon  becomes 
very  brittle  and  rotten :  the  alloy  is  greatly  inferior  to  gun- 
metal,  and  is  principally  used  on  account  of  the  cheapness 
of  the  mixture,  and  the  facility  with  which  it  is  turned  and 
filed. 

ALLOYS  OF  COPPER,  ZINC,  TIN,  AND  LEAD,  ETC. 

This  group  refers  principally  to  gnn-metal  alloys,  to  which  more  or  less  zinc 
is  added  by  many  engineers.  The  quantity  of  tin  in  every  pound  of  the 
alloy,  which  is  expressed  by  the  marginal  numbers,  principally  determines 
the  hardness. 

M.  Keller's  statues  at  Versailles  are  found,  as  the  mean 
of  four  analyses,  to  consist  of: 

Copper    .     .     .     .  91.40  or  about  14f  ounces. 

Zinc 5.53  "          1    ounce. 

Tin 1.70  "          Of      " 

Lead 1.37          "          0±      " 

In  100  parts  or  the  16  ounces. 

1J  to  2 1  oz.  tin  to  1  Ib.  copper  used  for  bronze  medals,  or  8  to  15 

per  cent,  tin,  with  the  addition  of  2  parts  in  each  100  of 

zinc,  to  improve  the  color. 

The  modern  so-called  bronze  medals  of  our  Mint  are  of 

pure  copper,  and  are  afterwards  bronzed  superficially. 
1£  oz.  tin,  |  zinc  to  16  oz.  copper.     Pumps  and  works  requiring 

great  tenacity. 


188  THE  PKACTICAL   METAL-WORKER'S  ASSISTANT. 

1|  oz.  tin,  2  oz.  brass,  16  oz.  copper  }  For  wheels  to  be  cut  into 

if       «       2,       "        16         "          J      teeth. 

2         *       If.      *        16          "  For  turning  work. 

2|      «       li       "        16          "  For  nuts  of  coarse  threads 

and  bearings. 

The  engineer  who  uses  these  five  alloys  recommends 
melting  the  copper  alone  ;  the  small  quantity  of  brass  is 
then  melted  in  another  crucible,  and  the  tin  in  a  ladle, — the 
two  latter  are  added  to  the  copper  when  it  has  been  removed 
from  the  furnace.  The  whole  are  stirred  together  and 
poured  into  the  moulds  without  being  run  into  ingots.  The 
real  quantity  of  tin  to  every  pound  of  copper  is  about  one- 
eighth  oz.  less  than  the  number  stated,  owing  to  the  addition 
of  the  brass,  which  increases  the  proportion  of  copper. 

If  oz.  tin,  If  oz.  zinc,  to  1  Ib.  copper.  This  alloy,  which  is  a  tough, 
yellow,  brassy,  gun-metal,  is  used  for  general  purposes.  It 
is  made  by  mixing  1J  Ib.  tin,  1£  Ib.  zinc,  and  10  Ibs.  of 
copper.  The  alloy  is  first  run  into  ingots. 

2 1  oz.  tin,  \  oz.  zinc,  to  1  Ib.  copper.  Used  for  bearings  to  sustain 
great  weights. 

2J  oz.  tin,  2J  oz.  zinc,  to  1  Ib.  copper,  were  mixed  by  Chantrey, 
and  a  razor  was  made  from  the  alloy.  It  proved  nearly  as 
hard  as  tempered  steel,  and  exceedingly  destructive  to  new 
files,  and  none  others  would  touch  it. 

1  oz.  tin,  2  oz.  zinc,  16  oz.  brass.  Best  hard  white  metal  for 
buttons. 

\  oz.  tin,  \\  oz.  zinc,  16  oz.  brass.  Common  white  metal  for 
buttons. 

10  Ibs.  tin,  6  Ibs.  copper,  4  Ibs.  brass,  constitute  white  solder.  The 
copper  and  brass  are  first  melted  together,  the  tin  is  added, 
and  the  whole  stirred  and  poured  through  birch  twigs  into 
water  to  granulate  it ;  it  is  afterwards  dried  and  pulverized 
cold  in  an  iron  pestle  and  mortar.  This  white  solder  was 
introduced  as  a  substitute  for  silver  solder  in  making  gilt 
buttons.  Another  button  solder  consists  of  10  parts  cop- 
per, 8  of  brass,  and  12  of  spelter  or  zinc. 

KEMARKS  ON  ALLOYS  OF  COPPER,  ZINC,  Tm,  AND  LEAD,  ETC. 

ORDINARY  YELLOW  BRASS  (copper  and  zinc)  is  rendered 
very  sensibly  harder,  so  as  not  to  require  to  be  hammered, 
by  a  small  addition  of  tin,  say  \  or  \  oz.  to  the  Ib.  On  the 
other  hand  by  the  addition  of  \  to  \  oz.  of  lead,  it  becomes 
more  malleable,  and  casts  more  sharply.  Brass  becomes  a 
little  whiter  for  the  tin,  and  redder  for  the  lead.  The  ad- 
dition" of  nickel  to  copper  and  zinc  constitutes  the  so-called 
German  silver. 

GUN  METAL  (copper  and  tin)  very  commonly  receives  a 
small  addition  of  zinc ;  this  makes  the  alloy  mix  better,  and 


METALS  AND  ALLOYS.  189 

to  lean  to  the  character  of  brass  by  increasing  the  mallea- 
bility without  materially  reducing  the  hardness.  The  zinc, 
which  is  sometimes  added  in  the  form  of  brass,  also  im- 
proves the  color  of  the  alloy  both  in  the  recent  and  bronzed 
states.  Lead  in  small  quantity  improves  the  ductility  of 
gun-metal,  but  at  the  expense  of  its  hardness  and  color ;  it. 
is  seldom  added.  Nickel  has  been  proposed  as  an  addition 
to  gun-metal  by  O'Donovan,  of  Dublin,  and  antimony  by 
his  countryman,  Dr.  Ure. 

POT  METAL  (copper  and  lead)  is  improved  by  the  addition 
of  tin,  and  the  three  metals  will  mix  in  almost  any  pro- 
portions. When  the  tin  predominates,  the  alloy  so  much 
the  more  nearly  approaches  the  condition  of  gun-metal. 
Zinc  may  be  added  to  pot  metal  in  very  small  quantity,  but 
when  the  zinc  becomes  a  considerable  amount,  the  copper 
takes  up  the  zinc,  forming  a  kind  of  brass,  and  leaves  the 
lead  at  liberty,  and  which  in  great  measure  separates  in 
cooling.  Zinc  and  lead  are  also  very  indisposed  to  mix 
alone,  although  a  little  arsenic  assists  their  union  by  "  kill- 
ing" the  lead,  as  in  shot  metal.  Antimony  also  facilitates 
the  combination  of  pot  metal;  7  lead,  1  antimony,  and  16 
copper,  mixed  perfectly  well  the  first  fusion,  and  the  alloy 
was  decidedly  harder  than  4  lead  and  16  copper,  and  ap- 
parently a  better  metal.  "  Lead  and  antimony,  though  in 
small  quantity,  have  a  remarkable  effect  in  diminishing  the 
elasticity  and  sonorousness  of  the  copper  alloys." 
GOLD  is  of  a  deep  and  peculiar  yellow  color.  It  melts  at  a 
bright  red  heat,  equivalent  to  2016°  of  Fahrenheit's  scale, 
and  when  in  fusion  appears  of  a  brilliant  greenish  color.  Its 
specific  gravity  is  19.3.  It  is  so  malleable  that  it  may  be 
extended  into  leaves  which  do  not  exceed  the  one  two 
hundred  and  eighty-two  thousandth  of  an  inch  in  thickness, 
or  a  single  grain  may  be  extended  over  56  square  inches  of 
surface.  This  extensibility  of  the  metal  is  well  illustrated 
by  gilt  buttons,  144  of  which  are  gilt  by  5  grains  of  gold, 
and  less  than  even  half  that  quantity  is  adequate  to  giving 
them  a  very  thin  coating.  It  is  also  so  ductile  that  a  grain 
may  be  drawn  out  into  500  feet  of  wire.  The  pure  acids 
have  no  action  upon  gold. 

GOLD  in  the  pure  or  fine  state  is  not  employed  in  bulk 
for  many  purposes  in  the  arts,  as  it  is  then  too  soft  to  be 
durable.  The  gold  foil  used  by  dentists  for  stopping  decayed 
teeth  is  perhaps  as  nearly  pure  as  the  metal  can  be  obtained; 
it  contains  about  6  grains  of  alloy  in  the  pound  troy,  or  the 
one-thousandth  part.  Every  superficial  inch  of  this  gold  foil 
or  leaf  weighs  f  of  a  grain,  and  is  42  times  as  thick  as  the 
leaf  used  for  gilding. 

The  wire  for  gold  lace  prepared  by  the  refiners  for  gold- 
lace  manufacturers,  requires  equally  fine  gold,  as  when  alloyed 


190  THE  PRACTICAL  METAL-WORKER'S  ASSISTANT. 

it  does  not  so  well  retain  its  brilliancy.  The  gold  in  the 
proportion  of  about  100  grains  to  the  pound  troy  of  silver, 
or  of  140  grains  for  double-gilt  wire,  is  beaten  into  sheets  as 
thin  as  paper;  it  is  then  burnished  upon  a  stout  red-hot 
silver  bar,  the  surface  of  which  has  been  scraped  perfectly 
clean.  When  extended  by  drawing,  the  gold  still  bearing 
the  same  relation  as  to  quantity,  namely,  the  57th  part  of 
the  weight  becomes  of  only  one-third  the  thickness  of  or- 
dinary gold-leaf  used  for  gilding.  In  water-gilding,  fine  gold 
is  amalgamated  with  mercury,  and  washed  over  the  gild- 
metal  (copper  and  tin),  the  mercury  attaches  itself  to  the 
metal,  and  when  evaporated  by  heat  it  leaves  the  gold  behind 
in  the  dead  or  frosted  state :  it  is  brightened  with  the  burn- 
isher. By  the  electrotype  process  a  still  thinner  covering 
of  pure  gold  may  be  deposited  on  silver,  steel,  and  other 
metals.  French  watch-makers  introduced  this  method  of 
protecting  the  steel  pendulum  springs  of  marine  chronometers 
and  other  time-pieces  from  rust. 

Fine  gold  is  also  used  for  soldering  chemical  vessels  made 
of  platinum. 

GOLD  ALLOYS. 

Gold-leaf  for  gilding  contains  from  3  to  12  grains  of  alloy 
to  the,  oz.,  but  generally  6  grains.  The  gold  used  by  re- 
spectable dentists,  for  plates,  is  nearly  pure,  but  necessarily 
contains  about  6  grains  copper  in  the  oz.  troy,  or  one  80th 
part ;  others  use  gold  containing  upwards  of  one-third  of 
alloy ;  the  copper  is  then  very  injurious. 

With  copper,  gold  forms  a  ductile  alloy  of  a  deeper  color, 
harder  and  more  fusible  than  pure  gold ;  this  alloy,  in  the 
proportion  of  11  of  gold  to  1  of  copper,  constitutes  English 
standard  gold;  its  density  is  17.157,  being  a  little  below  the 
mean,  so  that  the  metals  slightly  expand  on  combining. 
One  troy  pound  of  this  alloy  is  coined  into  46f  g  English 
sovereigns,  or  20  troy  poupds  into  934  sovereigns  and  a 
half.  (The  pound  was  formerly  coined  into  44  guineas  and 
a  half).  The  standard  gold  of  France  consists  of  9  parts  of 
gold  and  1  of  copper. 

For  Gold  Plate  the  French  have  three  different  standards: 
92  parts  gold,  8  copper ;  also  84  gold,  16  copper ;  and  75 
gold,  25  copper. 

In  England,  the  purity  of  gold  is  expressed  by  the  terms 
^•?;i  22,  18,  16,  12,  8,  carats,  etc.  The  pound  troy  is  supposed 
to  be  divided  into  24  parts,  and  the  gold,  if  it  could  be  ob- 
tained perfectly  pure,  might  be  called  24  carats  fine. 

The  "  Old  Standard  Gold,"  or  that  of  the  present  British 
currency,  is  called  fine,  there  being  22  parts  of  pure  gold 
to  2  of  copper. 


METALS  AND  ALLOYS. 


191 


The  "  New  Standard,"  for  watch-cases,  etc.  is  18  carats  of 
fine  gold,  and  6  of  alloy.  No  gold  of  inferior  quality  to  18 
carats,  or  the  "  New  Standard,"  can  receive  the  Hall  mark ; 
and  gold  of  lower  quality  is  generally  described  by  its  com- 
mercial value. 

The  alloy  may  be  entirely  silver,  which  will  give  a  green 

color,  or  entirely  copper  for  a  red  color,  but  the  copper  and 

,        silver  are  more  usually  mfeced  in  the  one  alloy  according  to 

the  taste  and  judgment  of  the  jeweler. 

The  following  alloys  of  gold  are  transcribed  from  the  memoranda 
of  the  proportions  employed  by  a  practical  jeweler  of  considerable 
experience.  When  it  is  otherwise  expressed,  it  will  be  understood 
all  these  alloys  are  made  with  fine  gold,  fine  silver,  and  fine  copper, 
obtained  direct  from  the  refiners.  And  to  insure  the  standard 
gold  passing  the  test  of  the  Hall,  3  or  4  grains  additional  of  gold 
are  usually  added  to  every  ounce. 

First  Q-roup.  Different  kinds  of  gold  that  are  finished  by  polish- 
ing, burnishing,  etc.,  without  necessarily  requiring  to  be 
colored : 

The  gold  of  22  carats  fine  is  so  little  used,  on  account  of  its 
expense  and  greater  softness,  that  it  has  been  purposely 
omitted. 


16 


18    carats,    or    New    Standard 
gold,  of  yellow  tint : 
15  dwt.     0  grs.  gold. 
2  dwt.  18  grs.  silver. 

2  dwt.     6  grs.  copper. 

20  dwt.     0  grs. 

18    carats  of  red  tint : 
15  dwt.     0  grs.  gold. 
1  dwt.  18  grs.  silver. 

3  dwt.     6  grs.  copper. 

20  dwt.     0  grs. 

16  carats  or  Spring  gold :  this, 
when  drawn  or  rolled  very 
hard,  makes  springs  little 
inferior  to  those  of  steel. 

1  oz.  16  dwt.  gold.  or  1.12 

6  dwt.  silver.         —     .4 
12  dwt.  copper.       —     .12 

2  oz.  14  dwt.  2.  8 


Second  Group.     Colored  golds :  these  all  require  to  be  submitted 
to  the  process  of  wet-coloring,  which  will  be  explained ;  they  are 


$15  gold  of  yellow  tint,  or  the 
fine  gold  of  the  jewelers ;  16 
carats  nearly : 

1  oz.     0  dwt.  gold. 

7  dwt.  silver. 
5  dwt.  copper. 

1  oz.  12  dwt. 

$15  gold  of  red  tint,  or 

carats : 

1  oz.     0  dwt.  gold. 
2  dwt.  silver. 

8  dwt.  copper. 

1  oz.  10  dwt. 


192  THE    PRACTICAL    METAL-WORKEK'S   ASSISTANT. 

used  in  much  smaller  quantities,  and  require  to  be  very  exactly 
proportioned. 


Full  red  gold : 

5  dwt.  gold. 
5  dwt.  copper. 

10  dwt. 

Bed  gold : 

10  dwt.  gold. 
1  dwt.  silver, 

4  dwt.  copper. 

15  dwt'. 

Green  gold : 

5  dwt.    0  grs.  gold. 

21  grs.  silver. 

5  dwt.  21  grs. 


Gray  gold :  (Platinum  is  also 
called  gray  gold  by  jewel- 
ers.) 

3  dwt.  15  grs.  gold. 

1  dwt.     9  grs.  silver. 

5  dwt.    0  grs. 

Blue  gold :  scarcely  used : 
5  dwt.  gold. 
5  dwt.  steel  filings. 

lOdwtT 

Antique  gold,  of  a  fine  green- 
ish-yellow color : 
18  dwt.  9  grs.  gold,     or  18.  9 
21  grs.  silver,  —   1.  .3 

—     .12 


18  grs.  copper,  - 


20  dwt.  0  grs. 


20.  0 


Third  Group.  Gold  solders :  these  are  generally  made  from  gold 
of  the  same  quality  and  value  as  they  are  intended  for,  with  a  small 
addition  of  silver  and  copper,  thus : 

Solder  for  $15  gold:* 


copper, 

Solder  for  22  carat  gold: 
1  dwt.  0  grs.  of  22  carat  gold. 
2  grs.  silver. 

1  gr.  copper. 

1  dwt.  3  grs. 

Solder  for  18  carat  gold : 
1  dwt.  0  grs.  of  18  carat  gold. 

2  grs.  silver. 
1  gr.   copper. 

1  dwt.  3  grs. 


1  dwt.     0  grs.  of  $15  gold. 
10  grs.  silver. 
8  grs.  copper. 

1  dwt.  18  grs. 

Solder  for  $10  gold:  but  mid- 
dling silver  solder  is  more 
generally  used. 

1  dwt.  fine  gold. 

1  dwt.  silver. 

2  dwt.  copper. 

4  dwt. 


Dr.  Hermstadt's  imitation  of  gold,  which  is  stated  not  only  to  re- 
semble gold  in  color,  but  also  in  specific  gravity  and  ductility,  con- 

*By  others,  4  grains  of  brass  are  added  to  the  solder ;  it  then  fuses  beauti- 
fully and  is  of  good  color.  Zinc  is  sometimes  added  to  other  good  solders  to 
increase  their  fusibility,  the  zinc  (or  brass  when  used)  should  be  added  at  the 
last  moment,  to  lessen  the  volatilization  of  the  zinc. 


METALS   AND  ALLOYS.  193 

sists  of  16  parts  of  platinum,  7  parts  of  copper,  and  1  zinc,  put  in  a 
crucible,  covered  with  charcoal  powder,  and  melted  into  a  mass. 

Gold  alloyed  with  platinum  is  also  rather  elastic,  but  the  plati- 
num whitens  the  alloy  more  rapidly  than  silver. 

LEAD  appears  to  have  been  known  in  the  earliest  ages  of  the 
world.  Its  color  is  bluish  white ;  it  has  much  brilliancy,  is 
remarkably  flexible  and  soft,  and  leaves  a  black  streak  on 
paper :  when  handled  it  exhales  a  peculiar  odor.  It  melts 
at  about  612°,  and  by  the  united  action  of  heat  and  air,  is 
readily  converted  into  an  oxide.  Its  specific  gravity,  when 
pure,  is  11.445 ;  but  the  lead  of  commerce  seldom  exceeds 
11.35. 

LEAD  is  used  in  a  state  of  comparative  purity  for  roofs, 
cisterns,  pipes,  vessels  for  sulphuric  acid,  etc.  Ships  were 
sheathed  with  lead  and  with  wood,  from  before  the  Christian 
era  to  1450,  after  which  wood  was  more  commonly  employed, 
and  in  1790  to  1800  copper  sheathing  became  general ;  of 
late  years,  lead  with  a  little  antimony  has  likewise  been 
used,  also  an  alloy  of  copper  and  zinc  and  galvanized  sheet 
iron.  The  most  important  alloys  of  lead  are  those  employed 
for  printers'  type,  namely,  about 

3  lead,  1  antimony,  for  the  smallest,  hardest  and  most 
brittle  types. 

4  lead,  1  antimony,  for  small,  hard,  brittle  types. 

5  lead,  1  antimony,  for  types  of  medium  size. 

6  lead,  1  antimony,  for  large  types. 

7  lead,  1  antimony,  for  the  largest  and  softest  types. 

In  addition  to  lead  and  antimony,  type-metal  also  contains 
from  4  to  8  per  cent,  of  tin,  and  sometimes  1  to  2  per  cent, 
of  copper ;  but  as  old  metal  is  always  used  with  the  new, 
the  proportions  are  not  exactly  known. 

Stereotype-plates  are  made  of  20  parts  of  lead,  4  of 
antimony,  and  1  of  tin. 

Baron  Wetterstedt's  patent  sheathing  for  ships,  consists 
•   %     of  lead  with  from  2  to  8  per  cent,  of  antimony ;  about  3 
per  cent,  is  the  usual  quantity.     The  alloy  is  rolled  into 
sheets. 

Similar  alloys,  and  those  of  lead  and  tin  in  various  prep- 
arations, are  much  used  for  emery  wheels  and  grinding- 
tools  of  various  forms  by  the  lapidary,  engineer,  and  others. 
The  latter  also  employs  these  readily-fused  alloys  for  tem- 
porary bearings,  guides,  screw  nuts,  etc. 

Organ  pipes  consist  of  lead  alloyed  with  about  half  its 
quantity  of  tin  to  harden  it.  The  mottled  or  crystalline  ap- 
pearance so  much  admired  shows  an  abundance  of  tin. 

Shot  metal  is  said  to  consist  of  40  Ibs.  of  arsenic  to  one 
ton  of  lead. 
13 


194  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

la  casting  sheet-lead,  the  metal  was  poured  from  a  swing- 
trough  upon  a  long  and  nearly  horizontal  table  covered 
with  a  thin  layer  of  coarse  damp  sand,  previously  levelled 
with  a  metal  rule  or  strike.  The  thickness  of  the  fluid 
metal  was  determined  by  running  the  strike  along  the  table 
before  the  lead  cooled,  the  excess  being  thus  swept  into  a 
spill-trough  at  the  lower  end  of  the  table ;  but  the  sheet- 
lead  now  more  commonly  used,  is  cast  in  a  thick  slab,  and 
reduced  between  laminating  rollers ;  it  is  known  as  "  milled- 
lead." 

The  metal  for  organ-pipes  is  prepared  by  allowing  the 
metal  to  escape  through  the  slit  in  a  trough,  as  it  is  slid 
along  a  horizontal  table,  so  as  to  leave  a  trail  of  metal  be- 
hind it ;  the  thickness  of  the  metal  is  fkgulated  by  the  width 
of  the  slit  through  which  it  runs,  and  the  rapidity  of  the 
traverse ;  a  piece  of  cloth  or  ticken  is  stretched  upon  the 
casting  table.  The  metal  is  planed  to  thickness,  bent  up 
and  soldered  into  the  pipes. 

Lead  pipes  are  cast  as  hollow  cylinders  and  drawn  out 
upon  triblets ;  they  are  also  cast  of  indefinite  length  with- 
out drawing.  A  patent  was  taken  out  for  casting  a  sheath 
of  tin  within  the  lead,  but  it  has  been  abandoned. 

Lead  shot  are  cast  by  letting  the  metal  run  through  a 
narrow  slit,  into  a  species  of  colander  at  the  top  of  a  lofty 
tower  ;  the  metal  escapes  in  drops,  which  for  the  most  part 
assume  the  spherical  form  before  they  reach  the  tank  of 
water  into  which  they  fall  at  the  foot  of  the  tower,  and  this 
prevents  their  being  bruised.  The  more  lofty  the  tower, 
the  larger  the  shot  that  can  be  produced ;  the  good  and  the 
bad  shot  are  separated  by  throwing  small  quantities  at  a 
time  upon  a  smooth  board  nearly  horizontal,  which  is 
slightly  wriggled ;  the  true  or  round  shot  run  to  the  bottom, 
the  imperfect  ones  stop  by  the  way,  and  are  thrown  aside 
to  be  re-melted ;  the  shot  are  afterwards  riddled  or  sifted 
for  size,  and  churned  in  a  barrel  with  black  lead. 

MERCURY  is  a  brilliant  white  metal,  having  much  of  the  color 
of  silver,  whence  the  terms  hydrargyrum,  argentum  vivum, 
and  quicksilver.  It  has  been  known  from  very  remote  ages. 
It  is  liquid  at  all  common  temperatures ;  solid  and  malleable 
-  at  400  F.,  and  contracts  considerably  at  the  moment  of  con- 
gelation. It  boils  and  becomes  vapor  at  about  670°.  Its 
specific  gravity  at  60°  is  13.5.  In  the  solid  state  its  den- 
sity exceeds  14.  The  specific  gravity  of  murcurial  vapor 
is  6.976. 

MERCURY  is  used  in  the  fluid  state  for  a  variety  of  philo- 
sophical instruments,  and  for  pressure  gages  for  steam-en- 
gines, etc.  It  is  sometimes,  although  rarely,  employed  for 
rendering  alloys  more  fusible ;  it  is  used  with  tin-foil  for 


METALS   AND   ALLOYS.  195 

silvering  looking-glasses,  and  it  has  been  employed  as  a 
substitute  for  water  in  hardening  steel.  Mercury  forms 
amalgams  with  bismuth,  copper,  gold,  lead,  palladium,  sil- 
ver, tin,  and  zinc. 

Mercury  is  commonly  used  for  the  extraction  of  gold  and 
silver  from  their  ores  by  amalgamation,  and  also  in  water- 
gilding. 

NICKEL  is  a  white  brilliant  metal,  which  acts  upon  the  magnetic 
needle,  and  is  itself  capable  of  becoming  a  magnet.  Its 
magnetism  is  more  feeble  than  that  of  iron,  and  vanishes  at 
a  heat  somewhat  below  redness,  630°.  It  is  ductile  and 
malleable.  Its  specific  gravity  varies  from  8.27  to  8.40 
when  fused,  and  after  hammering,  from  8.69  to  9.00.  It  is 
not  oxidized  by  exposure  to  air  at  common  temperatures, 
but  when  heated  in  the  air  it  acquires  various  tints  like 
steel ;  at  a  red-heat  it  becomes  coated  by  a  gray  oxide. 

NICKEL  is  scarcely  used  in  the  simple  state,  but  princi- 
pally used  together  with  copper  and  zinc,  in  alloys  that  are 
rendered  the  harder  and  whiter  the  more  nickel  they  contain ; 
they  are  known  under  the  names  of  albata,  British  plate, 
electrum,  German  silver,  pakfong,  teutanag,  etc. :  the  pro- 
portions differ  much  according  to  price ;  thus  the 

Commonest  are  3  to  4  parts  nickel,  20  copper,  and  16 
zinc. 

Best  .  are  5  to  6  parts  nickel,  20  copper,  and  8 
to  10  zinc. 

About  two-thirds  of  this  metal  is  used  for  articles  resem- 
bling plated  goods,  and  some  of  which  are  also  plated  ;  the 
remainder  is  employed  for  harness,  furniture,  drawing  and 
mathematical  instruments,  spectacles,  the  tongues  for  accor- 
dions, and  numerous  other  small  works. 

The  white  copper  of  the  Chinese,  which  is  the  same  as 
the  German  silver  of  the  present  day,  is  composed  of  31.6 
parts  of  nickel,  40.4  of  copper,  25.4  of  zinc,  and  2.6  of  iron, 
17.48 53.39 13.0 . 

The  white  copper  manufactured  at  Sutil  in  the  duchy  of 
Saxe  Hildburghausen,  is  said  by  Keferstein  to  consist  of 
copper  88.000,  nickel  8.753,  sulphur  with  a  little  antimony 
0.750,  silex,  clay,  and  iron  1.75.  The  iron  is  considered  to 
be  accidentally  introduced  into  these  several  alloys  along 
with  the  nickel,  and  a  minute  quantity  is  not  prejudicial. 

Iron  and  steel  have  been  alloyed  with  nickel ;  the  former 
(the  same  as  the  meteoric  iron  which  always  contains  nickel) 
is  little  disposed '  to  rust :  whereas  the  alloy  of  steel  with 
nickel  is  worse  in  that  respect  than  steel  not  alloyed. 

PALLADIUM  is  of  a  dull-white  color,  malleable  and  ductile, 
specific  gravity  is  about  11.3,  or  11.86  when  laminated. 


196  THE   PKACTICAL   METAL-WORKER'S  ASSISTANT. 

fuses  at  a  temperature  above  that  required  for  the  fusion 
of  gold. 

PALLADIUM  is  a  soft  metal,  but  its  alloys  are  all  harder 
than  the  pure  metal.  With  silver  it  forms  a  very  tough 
malleable  alloy,  fit  for  the  graduations  of  mathematical  in- 
struments, and  for  dental  surgery,  for  which  it  is  much  used 
by  the  French.  With  silver  and  copper,  palladium  makes 
a  very  springy  alloy,  used  for  the  points  of  pencil-cases, 
inoculating  lancets,  tooth-picks,  or  any  purpose  where  elas- 
ticity and  the  property  of  not  tarnishing  are  required. 
Thus  alloyed  it  takes  a  high  polish.  Pure  palladium  is 
not  fusible  at  ordinary  temperatures,  but  at  a  high  tempera- 
ture it  agglutinates  so  as  to  be  afterwards  malleable  and 
ductile. 

This  useful  metal  has  recently  been  found  in  some  abun- 
dance in  the  gold  ores  of  the  Minas  Gerae's  district.  Pal- 
ladium is  calculated  thoroughly  to  fulfil  many  of  the 
purposes  to  which  platinum  and  gold  are  applied  in  the 
useful  arts,  and  from  its  low  specific  gravity  it  may  be  ob- 
tained at  about  half  the  price  of  an  equal  bulk  of  platinum, 
and  at  one- eighth  that  of  gold ;  and  it  equally  resists  the 
action  of  mineral  acids  and  sulphuretted  hydrogen. 

Palladium  was  used  in  the  construction  of  the  balances 
for  the  United  States  Mint. 

PLATINUM  is  a  white  metal,  extremely  difficult  of  fusion,  and 
unaltered  by  the  joint  action  of  heat  and  air.  It  varies  in 
density  from  21  to  21.5,  according  to  the  degree  of  mechan- 
ical compression  which  it  has  sustained.  It  is  extremely 
ductile,  but  cannot  be  beaten  into  such  thin  leaves  as  gold 
and  silver. 

The  particles  of  the  generality  of  the  metals,  when  sep- 
arated from  the  foreign  matters  with  which  they  are  com- 
bined, are  joined  into  solid  masses  by  simple  fusion ;  but 
platinum  being  nearly  infusible  when  pure,  requires  a  very 
different  treatment. 

The  platinum  is  first  dissolved  chemically,  and  it  is  then 
thrown  down  in  the  state  of  a  precipitate ;  next  it  is  partly 
agglutinated  in  the  crucible  into  a  spongy  mass,  and  is  then 
compressed  whilst  cold  in  a  rectangular  mould  by  means 
of  a  powerful  fly -press  or  other  means,  which  in  operating 
upon  500  ounces,  converts  the  platinum  into  a  dense  block 
about  5  inches  by  4,  and  2J  inches  thick.  This  block  is 
heated  in  a  smith's  forge,  with  two  tuyeres  meeting  at  an 
angle,  at  which  spot  the  platinum  is  placed,  amidst  the 
charcoal  fire.  When  it  has  reached  the  welding  point,  or 
almost  a  blue  heat,  it  receives  one  blow  under  a  heavy  drop, 
or  a  vertical  hammer  somewhat  like  a  pile-driving  engine  ; 
it  then  requires  to  be  reheated,  and  it  thus  receives  a  fresh 


METALS  AND  ALLOYS.  197 

blow  about  every  twenty  minutes,  and  in  a  week  or  ten  days 
it  is  sufficiently  welded  or  consolidated  on  all  sides  to  admit 
of  being  forged  into  bars,  and  converted  into  sheets,  rods, 
or  wires  by  the  ordinary  means. 

The  motive  for  operating  upon  so  great  a  quantity  is  for 
making  the  large  pans  for  concentrating  sulphuric  acid  in 
only  two  or  three  pieces,  which  are  soldered  together  with 
fine  gold.  In  France  "2000  ounces  are  sometimes  welded 
into  one  mass,  so  that  the  vessels  may  be  absolutely  entire. 
For  small  quantities  the  treatment  is  the  same,  but  in 
place  of  the  drop,  the  ordinary  flatter  and  sledge-hammer 
are  used. 

PLATINUM  is  exceedingly  tough  and  tenacious,  and 
"  hangs  to  the  file  worse  than  copper ;"  on  which  account, 
when  it  is  used  for  the  graduated  limbs  of  mathematical 
instruments,  the  divisions  should  be  cut  with  a  diamond- 
point,  jvhich  is  the  best  instrument  for  fine  graduations  of 
all  kinds,  and  for  ruling  grounds,  or  the  lined  surfaces  for 
etchings. 

PLATINUM  is  employed  in  Russia  for  coin.  This  valuable 
metal  is  also  used  for  the  touch-holes  of  fowling-pieces,  and 
in  various  chemical  and  philosophical  apparatus  in  which 
resistance  to  fusion  or  to  the  acids  is  essential. 

The  alloys  of  platinum  are  scarcely  used  in  the  arts ; 
that  with  a  small  quantity  of  copper  is  employed  in  Paris 
for  dental  surgery. 

"  Dr.  Von  Eckart's  alloy  contains  platinum  2.40,  silver 
3.53,  and  copper  11.71.  It  is  highly  elastic,  of  the  same 
specific  gravity  as  silver,  and  not  subject  to  tarnish ;  it  can 
be  drawn  to  the  finest  wire  from  $  of  an  inch  diameter 
without  annealing,  and  does  not  lose  its  elasticity  by  an- 
nealing. It  is  highly  sonorous,  and  bears  hammering  red- 
hot,  rolling  and  polishing." 

Dr.  Ryan  added  to  silver  oiie-fourth  of  its  weight  of 
platinum,  and  he  considers  that  it  took  up  one-tenth  its 
weight.  The  alloy  became  much  harder  than  silver,  capable 
of  resisting  the  tarnishing  influences  of  sulphur  and  hydro- 
gen, and  was  fit  for  graduations. 

An  alloy  of  platinum  with  ten  parts  of  arsenic  is  fusible 
at  a  heat  a  little  above  redness,  and  may  therefore  be  cast  in 
moulds.  On  exposing  the  alloy  to  a  gradually-increasing 
temperature  in  open  vessels,  the  arsenic  is  oxidized  and  ex- 
pelled, and  the  platinum  recovers  its  purity  and  infusibility. 

Tin  also  so  greatly  increases  the  fusibility  of  platinum 
that  it  is  hazardous  to  solder  the  latter  metal  with  tin- 
solder,  although  gold  is  so  used. 

Platinum,  as  well  as  gold,  silver  and  copper,  are  deposited 
by  the  electrotype  process;  and  silver  plates  thus  platinized 
are  employed  in  the  galvanic  battery. 


198  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

KHODIUM  is  a  white  metal  very  difficult  of  fusion.  Its  specific 
gravity  is  about  11 ;  it  is  extremely  hard;  when  pure  the 
acids  do  not  dissolve  it. 

Rhodium  has  been  long  employed  for  the  nibs  of  pens, 
which  have  been  also  made  of  ruby,  mounted  on  shafts  of 
spring  gold.  These  kinds  have  had  to  endure  for  the  last 
seven  or  eight  years  the  rivalry  of  "  Hawkins's  Everlasting 
Pen,"  of  which  latter,  the  author,  from  many  months'  con- 
stant use,  can  speak  most  favorably.  "The  everlasting 
pen,"  says  the  inventor,  "  is  made  of  gold  tipped  with  a 
natural  alloy,  which  is  as  much  harder  than  rhodium  as 
steel  is  harder  than  lead  ;  will  endure  longer  than  the  ruby ; 
yields  ink  as  freely  as  the  quill ;  is  easily  wiped ;  and  if 
left  unwiped  is  NOT  CORRODED." 

Mr.  Hawkins  employs  the  natural  alloy  of  iridium  and 
osmium,  two  scarce  metals  discovered  by  Mr.  Tennant,  of 
Belfast,  amongst  the  grains  of  platinum.  Th^e  alloy  is  not 
malleable,  and  is  so  hard  as  to  require  to  be  worked  with 
diamond  powder.  The  metals  rhodium,  iridium,  and  os- 
mium, are  not  otherwise  employed  in  the  arts  than  for  pens, 
although  steel  has  been  alloyed  with  rhodium. 

The  inventor  of  the  gold  pen,  Mr.  Hawkins,  is  an 
American. 

SILVER  is  of  a  more  pure  white  than  any  other  metal.  It  has 
considerable  brilliancy,  and  takes  a  high  polish.  Its  specific 
gravity  varie§  between  10.4,  which  is  the  density  of  cast 
silver,  and  10.5  to  10.6,  which  is  the  density  of  rolled  or 
stamped  silver.  It  is  so  malleable  and  ductile,  that  it  may 
be  extended  into  leaves  not  exceeding  the  ten-thousandth 
of  an  inch  in  thickness,  and  drawn  into  wire  much  finer 
than  a  human  hair.  Silver  melts  at  a  bright-red  heat,  at 
1873°  of  Fahrenheit's  scale,  and  when  in  fusion  appears 
extremely  brilliant; 

SILVER  is  but  little  used  in  the  pure  unalloyed  state,  on 
account  of  its  extreme  softness,  but  it  is  generally  alloyed 
with  copper  in  about  the  same  proportion  as  in  our  coin, 
and  none  of  inferior  value  can  receive  the  "  Hall  mark." 
Diamonds  are  set  in  fine  silver,  and  in  silver  containing 
3  to  12  grs.  of  copper  in  the  ounce.  The  work  is  soldered 
with  pure  tin. 

The  sheet  metal  for  plated  works  is  prepared  by  fitting 
together  very  truly  a  short  stout  bar  of  copper  and  a  thin- 
ner plate  of  silver.  When  scraped  perfectly  clean  they  are 
.  tied  ^  strongly  together  with  binding  wire,  and  united  by 
partial  fusion  without  the  aid  of  solder.  The  plated  metal 
-  is  then  rolled  out,  and  the  silver  always  remains  perfectly 
united  and  of  the  same  proportional  thickness  as  at  first. 
Additional  silver  may  be  burnished  on  hot,  when  the  sur- 


METALS   AND   ALLOYS.  199 

faces  are  scraped  clean,  as  explained  under  gold.  This  is 
done  either  to  repair  a  defect,  or  to  make  any  part  thicker 
for  engraving  upon,  and  the  uniformity  of  surface  is  re- 
stored with  the  hammer.  In  addition  to  its  use  for  articles 
of  luxury,  the  important  service  of  copper  plated  with 
silver  for  the  parabolic  reflectors  of  light-houses  must  not 
be  overlooked.  These  are  worked  to  the  curve  with  great 
perfection  by  the  hammer  alone. 

Plated  spoons,  forks,  harness,  and  many  other  articles,  are 
made  of  iron,  copper,  brass,  and  German  silver,  either  cast 
or  stamped  into  shape.  The  objects  are  then  filed  and 
scraped  perfectly  clean  ;  and  fine  silver,  often  little  thicker 
than  paper,  is  attached  with  the  aid  of  tin  solder  and  heat. 
The  silver  is  rubbed  close  upon  every  part  with  a  bur- 
nisher. 

The  electrotype  process  is  also  used  for  plating  several 
of  the  metals  with  silver,  which  it  does  in  the  most  uniform 
and  perfect  manner.  The  silver  added  is  charged  by  weight 
at  about  three  times  the  price  of  the  metal.  The  German 
silver,  or  albata,  is  generally  used  for  the  interior  substance, 
as  when  the  silver  is  partially  worn  through  the  white  alloy 
is  not  so  readily  detected  as  iron  or  copper. 

SILVER  ALLOYS. 

The  alloy  with  copper  constitutes  plate  and  coin.  By  the 
addition  of  a  small  proportion  of  copper  to  silver,  the 
metal  is  rendered  harder  and  more  sonorous,  while  its  color 
is  scarcely  impaired.  Even  with  equal  weights  of  the  two 
metals,  the  compound  is  white.  The  maximum  of  hard- 
ness is  obtained  when  the  copper  amounts  to  one-fifth  of 
the  silver. 

"  For  silver  plate,  the  French  proportions  are  9  J  parts 
silver,  |  copper ;  and  for  trinkets,  8  parts  silver,  2  copper." 

Silver  solder»are  made  in  the  following  proportions : 

Hardest  silver  solder,  4  parts  fine  silver,  and  1  part 
copper  ;  this  is  difficult  to  fuse,  but  is  occasionally  employed 
for  figures. 

Hard  silver  solder,  3  parts  silver,  and  1  part  brass  wire, 
which  is  added  when  the  silver  is  melted,  to  avoid  wasting 
the  zinc. 

Soft  silver  solder  for  general  use,  2  parts  fine  silver,  and 
1  part  brass  wire.  By  some  few,  f  part  of  arsenic  is  ad- 
ded, to  render  the  solder  more  fusible  and  white,  but  it  be- 
comes less  malleable  ;  the  arsenic  must  be  introduced  at  the 
last  moment,  with  care  to  avoid  its  fumes. 

Silver  is  also  soldered  with  tin  solder  (2  tin,  1  lead),  and 
with  pure  tin. 

Silver  and  mercury  are  used  in  the  plastic  metallic  stop- 
ping for  teeth. 


200  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT 

TIN  has  a  silvery- white  color  with  a  slight  tint  of  yellow  ;  it  is 
malleable,  though  sparingly  ductile.  Common  tin-foil, 
which  is  obtained  by  beating  out  the  metal,  is  not  more  than 
one-thousandth  of  an  inch  in  thickness,  and  what  is  termed 
white  Duch  metal  is  in  much  thinner  leaves.  Its  specific 
gravity  fluctuates  from  7.28  to  7.6,  the  lightest  being  the 
purest  metal.  When  bent  it  occasions  a  peculiar  crackling 
noise,  arising  from  the  destruction  of  cohesion  amongst  its 
particles. 

When  a  bar  of  tin  is  rapidly  bent  backwards  and  for- 
wards, several  times  successively,  ic  becomes  so  hot  that  it 
cannot  be  held  in  the  hand.  When  rubbed,  it  exhales  a 
peculiar  odor.  It  melts  at  442°,  and,  by  exposure  to  heat 
and  air,  is  gradually  converted  into  a  protoxide. 

Pure  tin  is  commonly  used  for  dyers'  kettles;  it  is  also 
sometimes  employed  for  the  bearings  of  locomotive  car- 
riages and  other  machinery.  This  metal  is  beaten  into  very 
large  sheets,  some  of  which  measure  200  by  100  inches, 
and  are  of  about  the  thickness  of  an  ordinary  card :  the 
small  sized  foil  is  stated  not  to  exceed  one-thousandth  of  an 
inch  in  thickness.  The  metal  is  first  laminated  between 
rollers,  and  then  spread  one  sheet  at  a  time  upon  a  large 
iron  surface  or  anvil,  by  the  direct  blows  of  hammers  with 
very  long  handles ;  great  skill  is  required  to  avoid  beating 
the  sheets  into  holes.  The  large  sheets  of  tin-foil  are  only 
used  for  silvering  looking-glasses  by  amalgamation  with 
mercury.  Tin-foil  is  also  used  for  electrical  purposes.  The 
amalgam  used  for  electrical  machines,  is  7  tin,  3  zinc,  and  2 
mercury. 

TIN  is  drawn  into  wire,  which  is  soft  and  capable  of  be- 
ing bent  and  unbent  many  times  without  breaking ;  it  is 
moderately  tenacious  and  completely  inelastic.  Tin  tube  is 
extensively  used  for  gas  fitting  and  many  other  purposes 
by  Le  Eoy  &  Co.,  of  New  York;  it, has  been  recently  in- 
troduced in  an  ingenious  manner  for  tl^e  formation  of  very 
cheap  vessels,  for  containing  artists'  and  common  colors, 
besides  numerous  other  solid  substances  and  fluids,  required 
to  be  hermetically  sealed,  with  the  power  of  abstracting 
small  quantities. 

Tin  plate  is  an  abbreviation  of  tinned  iron  plate ;  the 
plates  of  charcoal  iron  are  scoured  bright,  pickled,  and  im- 
mersed in  a  bath  of  melted  tin  covered  with  oil,  or  with  a 
mixture  of  oil  and  common  resin ;  they  come  out  thoroughly 
coated.  Tinned  iron  wire  is  similarly  prepared :  there  are 
several  niceties  in  the  manipulation  of  each  of  these  pro- 
cesses, which  cannot  be  noticed  in  this  place. 

Tin  is  one  of  the  most  cleanly  and  sanatory  of  metals, 
and  is  largely  consumed  as  a  coating  for  culinary  vessels, 


METALS   AND   ALLOYS.  201 

although  the  quantity  taken  up  in  the  tinning  is  exceed- 
ingly small,  and  which  was  noticed  by  Pliny. 

Tin  imparts  hardness,  whiteness  and  fusibility  to  many 
alloys,  and  is  the  basis  of  different  solders,  and  other  im- 
portant alloys,  all  of  which  have  a  low  power  of  conduct- 
ing heat. 

PEWTER  is  principally  tin ;  mostly  lead  is  the  only  addi- 
tion, at  other  times  copper,  but  antimony,  zinc,  etc.,  are  used 
with  the  above,  as  will  be  separately  adverted  to.  The  ex- 
act proportions  are  unknown  even  to  those  engaged  in  the 
manufacture  of  pewter,  as  it  is  found  to  be  the  better  mixed 
when  it  contains  a  considerable  portion  of  old  metal  to 
which  new  metal  is  added  by  trial. 

Some  pewters  are  made  very  common ;  when  cast  they 
are  black,  shining  and  soft ;  when  turned,  dull  and  bluish. 
Other  pewters  only  contain  one  fifth  or  one-sixth  of  lead ; 
these  when  cast  are  white,  without  gloss  and  hard ;  such 
are  pronounced  very  good  metal,  and  are  but  little  darker 
than  tin.  The  French  legislature  sanctions  the  employment 
of  18  per  cent,  of  lead  with  82  of  tin  as  quite  harmless  in 
vessels  for  wine  and  vinegar. 

The  finest  pewter,  frequently  called  "tin  and  temper," 
consists  mostly  of  tin,  with  a  very  little  copper,  which 
makes  it  hard  and  somewhat  sonorous,  but  the  pewter  be- 
comes brown-colored  when  the  copper  is  in  excess.  The 
copper  is  melted,  and  twice  its  weight  of  tin  is  added  to  it, 
and  from  about  £  to  7  Ibs.  of  this  alloy  or  the  "temper," 
»  are  added  to  every  block  of  tin  weighing  from  360  to  390 
pounds. 

Antimony  is  said  to  harden  tin  and  to  preserve  a  more 
silvery  color,  but  is  little  used  in  pewter.  Zinc  is  employed 
to  cleanse  the  metal  rather  than  as  an  ingredient ;  some  stir 
the  fluid  pewter  with  a  thin  strip,  half  zinc  and  half  tin ; 
others  allow  a  small  lump  of  zinc  to  float  on  the  surface 
of  the  fluid  metal  whilst  they  are  casting,  to  lessen  the 
oxidation. 

White  metal  is  said  to  consist  of  3  J  cwt.  of  block  tin,  28 
Ibs.  antimony,  8  Ibs.  copper,  and  8  Ibs.  brass ;  it  is  cast  into 
ingots  and  rolled  into  very  thin  sheets. 

Tin  solders  are  very  much  used  in  the  arts. 

1  tin,  3  lead,  the  coarse  plumber's  solder,  melts  at  about 
500  F. 

2  tin,  1  lead,  the  ordinary  or  fine  tin  solder,  melts  at  about 
360  F. 

ZINC  is  a  bluish-white  metal,  with  considerable  lustre,  rather  hard, 
of  a  specific  gravity  of  about  6.8  in  its  usual  state,  but,  when 
drawn  into  wire,  or  rolled  into  plates,  its  density  is  aug- 
mented to  7  or  7.2.  In  its  ordinary  state  at  common  tern- 


202  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

peratures  it  is  tough,  and  with  difficulty  broken  by  blows 
of  the  hammer.  It  becomes  very  brittle  when  its  tempera- 
ture approaches  that  of  fusion,  which  is  about  773°;  but  at 
a  temperature  a  little  above  212°,  and  between  that  and 
300°,  it  becomes  ductile  and  malleable,  and  may  be  rolled 
into  thin  leaves,  and  drawn  into  moderately  fine  wire, 
which,  however,  possesses  but  little  tenacity.  When  a  mass 
of  zinc,  which  has  been  fused,  is  slowly  cooled,  its  fracture 
exhibits  a  lamellar  and  prismatic  crystalline  texture. 

ZINC,  which  is  commercially  known  as  "Spelter,"  although 
it  is  always  brittle  when  cast,  has  of  late  years  taken  its 
place  amongst  the  malleable  metals ;  the  early  stages  of  its 
manufacture  into  sheet,  foil  and  wire  are  stated  to  be  con- 
ducted at  a  temperature  somewhat  above  that  of  boiling 
water ;  and  it  may  be  afterwards  bent  and  hammered  cold, 
but  it  returns  to  its  original  crystalline  texture  when  re- 
melted.  It  has  been  applied  to  many  of  the  purposes  of 
iron,  tinned-iron,  and  copper ;  it  is  less  subject  to  oxidation 
from  the  effects  of  the  atmosphere  than  the  iron,  and  mtich 
cheaper,  although  less  tenacious,  ductile,  or  durable  than 
the  copper.  The  sheet  metals  when  bent  lengthways  of  the 
sheet  (or  like  a  roll  of  cloth),  are  less  disposed  to  crack 
than  if  bent  sideways ;  in  this  respect  zinc  and  sheet  iron 
are  the  worst :  the  risk  is  lessened  when  they  are  warmed. 

Zinc  is  applied  as  a  coating  to  preserve  iron  from  rust. 

Zinc  mixed  with  one-twentieth  its  weight  of  speculum 
metal  may  be  melted  in  an  iron  ladle,  and  made  to  serve 
for  some  of  the  purposes  of  brass,  such  as  common  chucks. 
The  alloy  is  sufficient  to  modify  the  crystalline  character, 
but  reserves  the  toughness  of  the  zinc ;  it  will  not,  however, 
bear  hammering  either  hot  or  cold.  Four  atoms  of  zinc 
and  one  of  tin,  or  133.2  and  57.9,  make  a  hard,  malleable, 
arid  less  crystalline  alloy. 

Biddery  ware,  manufactured  at  Biddery,  a  large  city,  60 
miles  N.  "W.  of  Hyderabad  in  the  East  Indies,  and  also  at 
Benares,  is  said  to  consist  of  copper  16  oz.,  lead  4  oz.,  and 
tin  2  oz.,  melted  together ;  and  to  every  3  oz.  of  this  alloy, 
16  pz.  of  spelter  or  zinc  are  added.  The  metal  is  used  as 
an  inferior  substitute  for  silver,  and  resembles  some  sorts 
of  pewter. 

The  foregoing  alloys  are  mostly  derived  from  actual 
practice,  and  although  it  has  been  abundantly  shown  that 
alloys  are  most  perfect,  when  mixed  according  to  atomic 
proportions,  or  by  multiples  of  their  chemical  equivalents, 
,  yet  this  excellent  method  is  little  adopted,  owing  to  various 
interferences. 

For  example,  it  is  in  most  cases  necessary  from  an  eco- 
nomic view,  to  mix  some  of  the  old  alloys  (the  proportions  of 
which  are  uncertain),  along  with  the  new  metals.  In  most 


METALS  AND  ALLOYS.  203 

cases  also,  unless  the  fusion  and  refusion  of  the  alloys  are 
conducted  with  considerably  more  care  than  ordinary  prac- 
tice ever  attains,  or  really  demands,  the  loss  by  oxidation 
completely  invalidates  any  nice  attempts  at  proportion ;  and 
which  proportions  can  be  alone  exactly  arrived  at  when  the 
combined  metals  are  nearly  or  quite  pure. 

The  chemical  equivalents  of  the  metals  upon  the  hydro- 
gen scale  are  appended ;  thus  for  mixtures  of  any  metals,  say 
tin  and  zinc,  instead  of  taking  arbitrary  quantities,  one 
atom  of  tin  or  57.9  parts  by  weight,  should  be  combined 
with  1,  2,  3,  4  or  5  atoms  o*f  zinc,  or  any  multiple  of  32.3 
parts,  and  so  with  all  other  metals. 

In  the  following  table  the  first  column  of  figures  denotes  the 
comparative  strength  of  the  metals,  glass  being  considered  as  unity; 
thus  steel  of  razor  temper  is  nearly  16  times  as  strong  as  glass  of 
equal  size ;  and  by  the  second  column,  it  is  seen  that  a  bar  of  steel 
one  inch  square  is  pulled  asunder  by  a  load  of  150,000  Ibs. 

NOTE. — The  following  Alloys  having  been  omitted  in  their  proper  places 
are  here  inserted  together. 

BABBITT'S  ANTI-ATTRITION  METAL — DIRECTIONS  FOR  PREPARING  AND  FITTING. — 
Melt  4  Ibs.  of  copper,  add.  by  degrees,  12  Ibs.  best  quality  Banca  tin,  8  Ibs. 
regulus  of  antimony,  and  12  Ibs.  more  of  tin  while  the  composition  is  in  a 
melted  state. 

After  the  copper  is  melted  and  4  or  5  Ibs.  of  tin  hare  been  added,  the  heat 
should  be  reduced  to  a  dull  red,  to  prevent  oxidation  ;  then  add  the  remainder 
of  the  metal  as  above.  In  melting  the  composition  it  is  better  to  keep  a 
small  quantity  of  powdered  charcoal  on  the  surface  of  the  metal.  The  above 
composition  is  called  "hardening."  For  lining  the  boxes,  take  one  Ib.  of 
this  hardening  and  melt  it  with  2  Ibs.  of  Banca  tin,  which  produces  the  lining 
metal  for  use.  Thus  the  proportions  for  lining  metal  are  4  Ibs.  of  copper,  8  Ibs. 
of  regulus  of  antimony,  and  96  Ibs.  of  Banca  tin. 

The  article  to  be  lined,  having  been  cast  with  a  recess  for  the  lining,  is  to 
be  nicely  fitted  to  a.  former,  which  is  made  of  the  same  shape  as  the  bearing. 
Drill  a  hole  in  the  article  for  the  reception  of  the  metal,  say  a  half  or  three- 
quarters  of  an  inch,  according  to  the  size  of  it.  Coat  over  the  part  not  to  be 
tinned  with  a  clay  wash,  wet  the  part  to  be  tinned  with  alcohol,  and  sprinkle 
on  it  powdered  sal  ammoniac  ;  heat  it  till  a  fume  arises  from  the  sal  ammo- 
niac, and  then  immerse  it  in  melted  Banca  tin,  taking  care  not  to  heat  it  so 
that  it  will  oxidize. 

After  the  article  is  tinned,  should  it  have  a  dark  color,  sprinkle  a  little  sal 
ammoniac  on  it,  which  will  make  it  of  a  bright  silver  color.  Cool  it  gradually 
in  water,  then  take  the  former  to  which  the  article  has  been  fitted,  and  coat  it 
over  with  a  thin  clay  wash,  and  warm  it  so  that  it  will  be  perfectly  dry ;  heat 
the  article  until  the  tin  begins  to  melt,  lay  it  on  the  former  and  pour  in  the 
metal,  which  should  not  be  so  hot  as  to  oxidize,  through  the  drilled  hole, 
giving  it  a  head,  so  that  as  it  shrinks  it  will  fill  up.  After  it  has  sufficiently 
cooled  remove  the  former. 

A  shorter  method  may  be  adopted  when  the  work  is  light  enough  to  handle 
quickly,  namely — When  the  article  is  prepared  for  tinning,  it  may  be  im- 
mersed in  the  lining  metal  instead  of  the  tin,  brushed  lightly  in  order  to 
remove  the  sal  ammoniac  from  the  surface,  placed  immediately  on  the  former 
and  lined  at  the  same  heating. 

FENTOX'S  ANTI-FBICTION  METAL. — 7J  parts  of  grain  zinc,  7$  of  purified  zino, 
and  1  of  antimony. 

ALLOY  OP  THE  STANDARD  MEASURE  USED  BY  GOVERNMENT. — 576  parts  copper, 
59  of  tin,  and  48  of  brass  (yellow,  2  copper  to  1  of  zinc). 

TUTENAODE. — 8  j>;irts  of  copper,  5  of  zinc,  and  3  of  nickel. 

EXPANSION  METAL. — 9  parts  of  lead,  2  of  antimony,  and  1  of  bismuth. 


204 


TABLES  OF  THE  COHESIVE  FORCE  OF  SOLID  BODIES. 
TABLE   I. — METALS. 

(A)  and  (I)  mark  the  highest  and  lowest  result  which  Muschenbroek  obtained  fror 
each  kind  of  iron. 


HETALS. 

Specific  cohe- 
sion. Glass  I. 

Coh.  force  of 
Ia  square  inch 
in  Ibs.  avoir. 

«§& 

'   ll 

OQ   60 

\ 

s 
- 

AUTHORITY. 

STEEL. 

15.927 

150,000 

7.78  to 

Soft  

IRON. 

Wire  

German  bar,markBR(h) 

12.739 

12.004 

9.880 
9.445 

120,000 

113,077 
93,069 
88,972 

7.84 

11 

Strength. 
Idem. 

Sickingen,  Ann.  de  Chimie,  xxv.  9. 
Muschenb.  Int.  ad  Phil.  Nat.  i.  426. 
Idem 

German  bar,  mark  L  (h) 
Wire  

9.119 
9.108 

85,000 
85,797 

Idem. 
Buffon  (Euvres  deGauthey,  ii.  153. 

Bar  

8.964 

84,443 

Liege  bar  (A)  

8.794 
8.685 

82,839 
81  901 

Muschenb.  Int.  ad  Phil.  Nat.  i.  426. 
Idem 

Bar  

8.581 

80  833 

.)_ 

Soufflot  Rondelet's  L'Art  de  Batir 

Bar  
Ooseraent  bar  (4)  
Cable  

8.492 
8.142 
7.752 

80,000 
76,697 
73  024 

o 

8 

4- 

35 

2 

CO 

iv.  500. 
Edin.  Encyclo.,  art.  Bridge,  544. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.4.26. 
Annals  of  Phil  vii  320 

German  bar,  mark  L  (1} 
German  bar,  common... 
Swedish  bar       1  ,« 
Oosement  bar    j  *  '  
Bar  of  best  quality  
L.iege  bar  (1)  
German  bar,  mark  BR(i) 
Bar*  

7.382 
7.339 

7.296 

7.006 
6.621 
6.514 
6  480 

69,538 
69,133 

68,728 

66,000 
62,369 
61,361 
61  041 

• 

Muschenb.  Intr.  ad  Phil.  Nat.i.  426. 
Idem. 

Idem. 

Rumford,  Phil.  Mag.  x.  51. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.  426. 
Idem. 

Bar  of  good  quality  
Cable  

5.839 
5  787 

55,000 
54  513 

Rumford,  Phil.  Mag.  x.  51. 
Annals  of  Phil  x   311 

Bar,  fine-grained  
medium  fineness.... 
coarse-grained  

CAST  IRON. 

French  J 

5.306 
3.618 
2.172 

7  470 

49,982 
34,081 
20,460 

70  367 

Rondelet,  L'Art  de  Batir,  iv.  502. 
Idem. 
Idem. 

French,  soft  ^  f 

6  754 

63  622 

English... 

5  590 

French  ; 

5.412 
4.540 

50,981 
42  666 

Ex.  i. 
L'Ecole  des  Ponts,  etc.  Gaut.  ii.  150. 

English,  soft  J 

4.334 

40,824 

j 

Banks,  Greg.  Mech.  i.  148.  Ex.  iii. 

*  This  is  the  mean  result  of  thirty-three  experiments. 

f  Kirwan,  Elem.  Miner,  ii.  155. 

I  Calculated  from  experiments  on  the  transverse  strength,  by  arts.  14  and  15. 

I  Yielding  to  the  file  without  difficulty. 


205 


TABLES  OF  THE  COHESIVE  FORCE  OF  SOLID  BODIES. 
TABLE   I. — Continued. 


MBTALS. 

Specific  cohe- 
sion. Glass  I. 

Coh.  force  of 
a  square  inch 
in  Ibs.  avoir. 

<§  if* 

1*5 

&i 

Hardness. 

AUTHORITT. 

CAST-IRON. 

French  gray  * 
Gray,  of  C'ruzot,  2d  fu- 
sion                    .         * 

4.000 
3.257 
3.202 

6.606 
2.396 
2.152 

5.995 
5.625 

4.090 
4.342 

3.279 
2.171 

0.7568 
0.706 
0.565 
0.3906 
0.342 

0.345 
0.3193 

2.394 
1.762 
0.3118 
0.2855 

0.3533 
0.334 
0.274 
0.2704 
0.094 

0.1126 

37,680 
30,680 
30,162 

61,228 
22,570 
20,272 

56,473 
52,987 

38,257 
40,902 

30,888 
20,450 

7,129 
6,650 
5,322 
3,679 
3,211 

8,250 
3,008 

22,551 
16,616 
2,937 
2,689 

3,328 
3,146 
2,581 
2,547 
885 

1,060 

8.182 
8.726 

20.847 

11.091 
19.238 

7.295    !• 
7.2165 
6.1256J 

9.8101 
9.926  j 

7.215  I 

11.407 
11.348 
11.282 

11.479 
4.500 

»i 
N 

-2 
«i 

fit 
r| 

6J 

5? 

'>} 

Rondelet,  L'Art  de  Batir,  iv.  514. 
Ramus,  Gauthey,  ii.  150. 
Idem.t 

Sickingen,  Ann.  de  Chimie,  xxv.  9. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.417. 
Idem. 

Morveau,  Ann.  de  Chimie,  xxv.  8. 
Sickingen,  Ann.  de  Chimie,  xxv.  9. 

Sickingen,  Ann.  de  Chimie,  xxv.  9. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.  417. 

Sickingen,  Ann.  de  Chimie,  xxv.  9. 
Muschenb.  Intr.  ad  Phil.  Nat.i.  417. 

Morveau,  Ann.  de  Chim.  Ixxi.  194. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.417. 
Idem. 
Idem. 
Idem. 

Muschenb.  Intr.  ad  Phil.  Nat  i.417. 
Idem.  i.  454. 

Morveau,  Ann.  de  Chim.  Ixxi.  194. 
By  my  trial. 
Muschenb.  Int.  ad  Phil.  Nat.  i.417. 

By  my  trial. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.  452. 
Idem. 
Morvean,  Ann.  de  Chim.  Ixxi.  194. 
Muschenb.  Intr.  ad  Phil.  Nat.  i.  452. 

Muschenb.  Intr.  ad  Phil.  Nat  i.  417. 

Gray,  of  Cruzot,  1st  fu- 
sion    * 

COPPER. 

Wire..             

Cast,  Barbary  

PLATINUM. 

Wire  

Wire                  

SILVER. 

Wire  

GOLD. 

Wire  

Cast.  

TIN. 

Wire             .     . 

Cast,  English  black  
idem  

Malacca  

BISMUTH. 

Cast  

ZINC. 

Patent  sheet  

Cast,  Goslar,  from  

to  

LEAD. 

Milled  

Wire 

Wire  
Wire  

Cast,  English  
Antimony,  cast.  

*  Calculated  from  experiments  on  the  transverse  strength,  by  arts.  14  and  15. 

|  In  the  operation  of  casting,  the  surface  of  the  iron  always  becomes  much  harder,  and 
is  more  tenacious  than  the  internal  part* ;  hence  the  strength  of  a  small  specimen  is  always 
greater  than  that  of  a  large  one. 

N.  n.— When  the  specific  gravity  is  not  referred  to  a  separate  authority,  it  ia  to  be  con- 
sidered that  of  the  specimen  of  which  the  cohesive  force  is  given. 

J  Kirwan's  Miner,  vol.  ii.  g  Thomson's  Chemistry,  rol.  L 


206 


TABLES  OF  THE  COHESIVE  FORCE  OF  SOLID  BODIES. 
TABLE   II. — ALLOTS. 


ALLC 

Y    OF 

Specific  cohe- 
sion. Glass  I. 

Cohesion  of 
square  inch 
in  Ibs.  avoir. 

«  .£> 

to  Eb 

AUTHORITY. 

Parts. 

Parts. 

Gold  2 

Silver  

2.972 

28,000 

Musch.  Encyclop.  Brit.  art. 

Gold  5 

Copper  

5.307 

50,000 

Idem.                     [Strength. 

Silver  5 

Copper  

5.148 

48,500 

Idem. 

Silver  4 

Tin  

4.352 

41,000 

Idem. 

Brass  

4.870 

45,882 

Muschenb..  Colson   1.  242. 

Copper  10 

Tin  

3.407 

32,093 

Musch.  Intr.  ad  Phil.  Nat. 

Tin    

3.831 

36,088 

Idem.                         fi.  428. 

Copper  6 

Tin  

4.687 

44,071 

Idem. 

Copper  4 

Tin  

3.794 

35,739 

Idem. 

Copper  2 

Tin  

0.108 

1,017 

Idem. 

Copper  1 

Tin  

0.077 

725 

Idem. 

Tin,  English  10 

Lead  . 

0.733 

'6,904 

Musch.  Intr.  ad  Phil.  Nat. 

Tin,    8 

Lead  

0.841 

7,922 

Idem,                          [i.  438. 

Tin,    6 

Lead  

0.849 

7,997 

Idem. 

Tin,    4 

Lead  

1.126 

10,607 

Idem. 

Tin,    2 

Lead. 

0.793 

7,470 

Idem. 

Tin,    1 

Lead  

0.751 

7,074 

Idem. 

Tin,  Bane*    10 

Antimony... 

1.187 

11,181 

7.359 

Musch.  Intr.  ad  Phil.  Nat. 

Tin,    8 

Antimony... 

1.049 

9,881 

7.276 

Idem.                         [i.  442. 

Tin,    6 

Antimony... 

1.341 

12,632 

7.228 

Idem. 

Tin,    4 

Antimony... 

1.431 

13,480 

7.192 

Idem. 

Tin,    2 

Antimony... 

1.277 

12,029 

7.105 

Idem. 

Tin,    1 

Antimony... 

0.338 

3,184 

7.060 

Idem. 

Tin,    10 

Bismuth  

1.347 

12,688 

7.576 

Musch.  Intr.  ad  Phil.  Nat. 

Tin,    4 

Bismuth  

1.772 

16,692 

7.613 

Idem.                         [i.  443. 

Tin,    2 

Bismuth  

1.488 

14,017 

8.076 

Idem. 

Tin,    1 

Bismuth  

1.276 

12,020 

8.146 

Idem. 

Tin,    1 

Bismuth  2 

1.063 

10,013 

8.58 

Idem. 

Tin,    1 

Bismuth  4 

0.836 

7,875 

9.009 

Idem. 

Tin,    1 

Bismuth  10 

0.411 

3,871 

9.439 

Idem. 

Tin,    10 

Zinc,  Indian     1 

1.371 

12,914 

7.288 

Musch.  Intr.  ad  Phil.  Nat. 

Tin,    2 

Zinc...               1 

1.595 

15  025 

7  000 

Idem                            fi  444 

Tin,    1 

Zinc  1 

L682 

15^844 

7^321 

Idem! 

Tin,    1 

Zinc  2 

1.701 

16,023 

7.100 

Idem. 

Tin,    1 

Zinc  10 

0.602 

5,671 

7.130 

Idem. 

Tin.  English    1 

Zinc,  Goslar     1 

0.958 

9,024 

Musch.  Intr.  ad  Phil.  Nat. 

Tin,    2 

Zinc  1 

1.164 

10,964 

Idem.                          [i.  446. 

Tin,    4 

Zinc  1 

1.089 

10,258 

Idem. 

Tin,    8 

Zinc  1 

1.126 

10,607 

Idem. 

Tin,    1 

Antimony...     1 

0.154 

1,450V 

7.000 

Musch.  Intr.  ad  Phil.  Nat. 

Tin.    3 

Antimony...     2 

0.338 

3*184 

Idem.                         [i.  448. 

Tin,    4 

Antimony...     1 

1.202 

11,323 

Idem. 

Lead,  Scotch    1 
Lead,   2 
Lead,   10 

Bismuth  1 
Bismuth  1 
Bismuth  1 

0.777 
0.620 
0.300 

7,319 
5,840 
2,826 

10.S31 
11.090 
10.827 

Musch.  Intr.  ad  Phil.  Nat, 
Idem.                         [i.  454. 
Idem. 

207 


TABULAR  VIEW  OF  SOME  OF  THE  PROPERTIES  OF  METALS. 


Specific 
gravity. 
Platinum  :  20.98 
Gold                      .            .  19  258 

Chemical 
equiva- 
lents. 
98.8 
199.2 
98.8 
99.7 
202. 
53.3 
103.6 
52.2 
108. 
71. 
217. 
31.6 
55.8 
29.5 
29.5 
28. 
47.7 
57.9 
32.3 
27.7 
64.6 
64.2 
37.7 
24.3 
23.3 
39.15 

acific  gra- 
ponents. 

m. 

>  Infusible  below  a  red  heat.  Fusible  below  a  red  heat. 

FOSIBIL1TT. 

Fahrenheit. 

Sodium  190    " 

Tungsten  17.50 
Mercury                           .  13  568 

Tin  442    " 
Bismuth  „  497    " 
Lead  612    " 

Palladium  11.50 

Lead            ..           .      ..  11.35 

Tellurium,  rather  less  fusi- 
ble than  lead. 
Arsenic,  undetermined. 
Zinc             .                               773    " 

Rhodium  11.0 
Silver           10.47 

Bismuth  9.80 
Uraniuta  9.00 
Copper                 .         ...     8  89 

Antimony,  a  little  below  a 
red  heat. 
Cadmium    about                       442    " 

Cadmium  8.60 
Cobalt  8.53 
Nickel                            ..     8  27 

Silver             ..                          1873  deg 

Iron  7.78 

/Copper  1996    " 

Molybdenum        7  40 

'Gold  2016    " 

Tin  7.30 

Cobalt,  rather  less    fusible 
than  iron. 
Iron    cast      2786    " 

teSsSGS 

/Nickel,  nearly  the  same  as  Cobalt. 
/Palladium  \ 
^Molybdenum....                      ^ 
(Uranium  Almogt  infusible  and 
Tungsten  not  tQ  be          ured 
JChroimum  1      .     button£  b       h 
[T'tamum  \     heat  of  a  smith's 

Zinc  7.00 

Manganese  6.85 

Tellurium  6.10 
Arsenic  ..,  5.8 

Sodium       0972 

ALLOTS  possessed  of  greater  sp 
vity  than  the  mean  of  their  coa 

Gold  and    Zinc. 
—        Tin. 
—        Bismuth. 
—        Antimony. 
—        Cobalt. 
Silver  and  Zinc. 
—        Lead. 
—        Tin. 
—        Bismuth. 
—        Antimony. 
Copper  and  Zinc. 
—        Tin. 
—        Palladium. 
—        Bismuth. 
—        Antimony. 
Lead  and  Bismuth. 
—         Antimony. 
Platinum  and  Molybdenu 
Palladium  and  Bismuth. 

OsmUun."."    ""i1       f°rge>   but   fusible 

RhoSm:::::::::   dr°«cn  W°»P*P«. 

\Platinum  
Columbium  / 

LOTS  having  a  specific  gravity  inferior 
to  the  mean  of  their  components. 

Gold  and   Silver. 
—        Iron. 
—        Lead. 
—        Copper. 
—        Iridium. 
—        Nickel. 
Silver  and  Copper. 
Copper  and  Lead. 
Iron   and   Bismuth. 
—        Antimony. 
—         Lead. 
Tin     and    Lend. 
—         Palladium. 
—         Antimony. 
Nickel  and  Arsenic. 
Zinc  and  Antimony. 

208 


TABULAR  VIEW  OF    METALS—  Continued. 


.  .•  J 
Titanium  
Manganese  
Platinum  
Palladium  
Copper  
Gold  
Silver  
Tellurium  
Bismuth  
Cadmium  
Tin  

IARDNESS. 

Harder  than  Steel. 
Scratched  by  Calcspar. 

•  Scratch  glass. 
Scratched  by  glass. 

MALLEABILITY, 

Or  admit  of  being  extended  by  the 
hammer. 
Gold.                            Zinc. 
Silver.                           Iron. 
Copper.                        Nickel. 
Tin.                              Palladium. 
Cadmium.                     Potassium. 
Platinum.                    Sodium. 
Lead.                          Frozen  Mercury. 

DUCTILITY, 

Or  admit  of  being  drawn  into  wires. 
Gold.                            Tin. 
Silver.                          Lead. 
Platinum.                    Nickel. 
Iron.                             Palladium 
Copper.                       Cadmium. 
Zinc. 

TENACITY. 

Weights  sustained  by  wires  0.787  of  a 
line  diameter. 
Iron  549  Ibs.  250  dec.  pts. 

Chromium  
Rhodium  
Nickel  
Cobalt.  

Antimony  
Zinc 

Lead  Scratched  by  the  nail. 

soliumT.:::::::  Soft  M  wax  <at  60  de*-> 

Mercury  Liquid. 

BRITTLENESS. 

The    following    metals    are    brittle,    and 
most  of  them  may  even  be  reduced  to 
powder. 
Antimony.                    Manganese. 
Arsenic.                        Molybdenum. 
Bismuth.                      Rhodium. 
Cerium.                        Tellurium. 
Chromium.                   Titanium. 
Cobalt.                          Tungsten. 
Columbiutn.                 Uranium. 

Copper                          302    "    278         " 

Platinum  274    "    320 

Gold                              150    "     753 

Zinc  109    "     540 

Tin  34    "     630 

Lead  ,  27    "     621 

Elasticity  and  sonorousness  belong  to  the 
hardest  metals  only,  and  are  most  evident 
in  certain  alloys. 
Odor  and  taste  are  most  remarkable  in 
copper,  iron,  and  tin. 

LINEAR  DILATATIONS  BY  HE, 
Dimensions  which  a  bar  takes  at  212°,  who 
at  32°  is  1.000000;  also  its  dilatation 
fractions. 
Platinum  1.00091085  or  one  10 

\.T. 
se  length 
in  vulgar 

97th  part. 
00th     " 
23d     " 
Blst     " 
24th    " 
91st     " 
18th    " 
67th    « 
57th     " 
50th     " 
24th     " 
17th     " 
99th     " 
24th     " 
50th     " 
36th     " 

he  various 
tionary  of 

POWER   OF    CONDUCTING 
HEAT. 
From  Detpreti'a  Experiments.* 
Conducting  power. 
Gold                                  100 

Palladium  

1.00100000      "       10 
1.00108300       "        9 

Platinum  98.1 
Silver                                  97  3 

Cast  iron  
Steel  
Wrought  Iron... 
Bismuth  
Gold  

1.00111025       "        9 
1.00121286      "        8 
1.00124860       "        8 
1.00139200       "        7 
1.00149824       "         6 

Copper  89.82 
Iron  37.41 
Zinc  36.37 
Tin        30.38 

Lead  17.96 

Gun  metal  (C.S,T.l)     1.00181700       "        5 

Marble  2.34 
Porcelain  1.22 

Speculum  metal 

Silver 

1.00193300       "        5 
1.00200183       "        4 
1.00235840       "         4 
1  00285768       "         3 

Brick  earth  1.13f 

Tin  
Lead  

*  Ann.  de  Chim.  et  de  Phys. 
xix.  97. 
f  Traite"  Elfimentaire  de  Phy- 
sique, par  M.  Despretz,  p.  20,  as 
quoted  by  Dr.  Thomson,  on  Heat 
and  Electricity,  p.  103. 

Zinc  

...  i  nn9Q7Rin      «        t 

The  above  are  the  mean  proportions  oft 
examples  of  each  metal,  given  in  Ure's  Die 
Chemistry  and  elsewhere. 

209 


WEIGHTS  OF   WROUGHT-IRON,  STEEL,  COPPER,  AND   BRASS   WIRE 
AND   PLATES. 

The  specific  gravities  to  determine  the  weights  of  the  following- 
named  metals,  and  the  calculations  of  them,  were  taken  and  made 
by  Charles  H.  Haswell,  of  New  York,  for  the  well-known  manu- 
facturers, Messrs.  J.  R.  Brown  &  Sharpe,  of  Providence,  E.  I. 
Diameter  and  thickness  determined  by  American  gage : — 


WIRE— PER  LINEAL  FOOT. 


PER  LINEAL  FOOT. 


.40964 
.36480 
.32486 
.28930 
.25763 
.22942 
.20431 
.18194 
.16202 
.14428 
.12849 
.11443 
.10189 


.071961 


.057WM 
.050320 


17  .045257 

18  1 .040303 

19  | .035890 

20  .031961 
21 


23  |  .022671 
• '  .020100 


.oo,r>«i4 

.006000 
.004453 
.003966 
.003531 
.003144 


Lbs. 
.660740 
.444683 


.279665 
.221789 


.1101)16 
.087720 
.069565 
.055165 
.043751 


.177648 
.140796 
.111660 
.088548 
.070221 
.055685 
.044164 


.027512 
.021820 
.017304 
.013722 
.010886 
.008631 
.006845 
.005407 
.004304 


.027772 
.022026 
.017468 


.008712 


.0021 
.0017 


.002708 
147 
1703 
.001350 
.001071 
.0008491 
.0006734 
.0006340 
.0004236 
.0003358 


.005478 

.004304 

.003445 

.002734 

.002167 

.001719 

.001363 

.001081 

.0008571 

.0006797 

.0005391 

.0004275 


.0002113 
.0001675 
.0001328 
.0001053 

.00008366 


.00005255  I 
.00004166  I 
.00003306 
.00002(320  ' 


.0002132 
.0001691 
.0001341 
.0001065 

.00008446 
.00006687 
.00005304 
.00005205 
.(XXKI3336 
.00002(544 


Lbs. 
.640513 
.607946 


.319451 
.253342 
.200911 


.049976 
.039636 
.031426 
.024924 
.019766 
.016674 
.012435 


.007819 
.006199 
.004916 


.001945 
.001642 
.001223 


.0004837 


.0003042 
.0002413 
.0001913 
.0001617 
.0001204 


.0000767 


.00004768 

.<xxx>:n75 


Lbs. 
.606176 
.479908 


,150522 
,119376 
,094666 
,075076 
,069646 
.047219 
,037437 


.018676 
.014809 
.011746 


.007687 
.006857 
.004645 


.002317 


.001467 
.001165 

.0009163 
.0007267 
.0005763 
.0004570 
.0003624 
.0002874 


.0001808 
.0001434 
.0001131 
.00009015 
.0000715 
.00005671 
.00004496 


Lba. 
17.26 
15.3616 
33.68 
12.1823 
10.8488 
9.6611 


7.6616 
6.8228 
6.0768 
6.4105 
4.8184 
4.2911 


3.4028 


2.4032 
2.1401 
1.9068 
1.6971 
1.6114 
1.3459 
1.1986 
1.0673 
.96051 
.84641 
.75376 
.67126 
.69775 
.63231 
.47404 
.42214 
.37694 
.3348 
.29813 
.2656 
.2364 
.21053 
.1876 
.16699 
.14869 
.13241 
.1179 


Lbs. 
17.48 
16.6663 
13.8624 
12.3447 
10.9934 
9.7899 
8.7180 
7.7638 
6.9137 
6.1668' 


4.3483 
3.8718 
3.4482 
3.0707 
2.7346 
2.4362 
2.1686 
1.9312 
1.7198 
1.6315 
1.3638 
1.2146 
1.0816 
.96319 
.8577 


.42777 

.38095 

.33926 

.3021 

.269041 

.23966 

.21333 

.19 

.16921 

.16067 

.13418 

.11947 


Lbs. 


18.5567 
16.5254 
14.7162 
13.1053 
11.6706 
10.3927 


7.3395 
6.5359 


4.1106 


3.2598 
2.9030 
2.5862 
2.3021 
2.0601 
1.B267 
1.6258 
1.4478 
1.2893 
1.1482 
1.0226 
.91063 
.81087 
.72208 
.64303 
.67264 
.60994 
.46413 
.40444 
.36014 
.32072 
.28667 
.26431 
.2266 
.20172 
.17961 
.16096 
.14242 


IJ>8. 

19.688 
17.6326 
15.6134 
13.904 
12.382 


9.8192 
8.7446 
7.787 
6.9345 
6.1752 
5.4994 
4.8976 
4.3609 


3.4586 

3.0799 

2.7428 

2.4426 

2.1751 

1.937 

1.725 

1.6361 

1.3679 

1.2182 

1.0849 


.76612 


.60765 

.63103 

.48180 

.42907 

.3JK12 

.3-ffM 

.30302 

.26981 

.24028 

.2140    i 

.19069 

.1897 

.16113 


Specific  Gravities ..     7.7741      7.8471      8.8801      8.386  j|      7.2001      7.2961       8.6981       8.21& 
Weiyftfso/acub./t.  585.81     \  490.46    |  554.983  '  524.16     j  460.         1  456.         |  643.6      1  613.6 

14 


210  THE    PRACTICAL    METAL- WORKER^   ASSISTANT. 

4p 
CHAPTER  XIII. 

REMARKS  ON  THE  CHARACTERS  OF  THE  METALS  AND  ALLOYS. 

HARDNESS,  FRACTURE,  AND  COLOR  OF  ALLOYS.— The  object  of 
the  present  chapter  is  to  explain  in  a  general  way  some  of  the  pe- 
culiarities and  differences  amongst  alloys,  prior  to  entering  on  the 
means  of  melting  the  metals,  without  which  process  alloys  cannot 
be  made :  yet  notwithstanding  that  the  list  contains  the  greater 
number  of  the  alloys  in  ordinary  use,  and  many  others,  it  is  merely 
a  small  fraction  of  those  which  might  be  made. 

It  is  also  stated  that  metals  appear  to  unite  with  one  another  in 
every  proportion,  precisely  in  the  same  manner  as  sulphuric  acid 
and  water.  Thus  there  is  no  limit  to  the  number  of  alloys  of  gold 
and  copper.  The  same  might  be  said  of  many  other  metals,  and 
when  the  alloys  compounded  of  three,  four,  or  more  metals,  are 
taken  into  account,  the  conceivable  number  of  alloys  becomes  almost 
unlimited.  It  is  certain,  however,  that  metals  have  a  tendency  to 
combine  in  definite  proportion ;  for  several  atomic  compounds  of 
this  kind  occur  native.  It  is  indeed  possible  that  the  variety  of 
proportions  in  'alloys  is  rather  apparent  than  real,  arising  from  the 
mixture  of  a  few  definite  compounds  with  each  other,  or  with  un- 
combined  metal ;  an  opinion  not  only  suggested  by  the  mode  in 
which  alloys  are  prepared,  but  in  some  measure  supported  by 
observation. 

It  appears  to  be  scarcely  possible  to  give  any  sufficiently  general 
rules,  by  which  the  properties  of  alloys  may  be  safely  inferred  from 
those  of  their  constituents ;  for  although,  in  many  cases,  the  work- 
ing qualities  and  appearance  of  an  alloy,  may  be  nearly  a  mean 
proportional  between  the  nature  and  quantities  of  the" metals  com- 
posing it ;  yet  in  other  and  frequent  instances  the  deviations  are 
excessive,  as  will  be  seen  by  several  of  the  examples  referred  to. 

Thus,  when  lead,  a  soft  and  malleable  metal,  is  combined  with 
antimony,  which  is  hard,  brittle,  and  crystalline,  in  the  proportions 
of  from  twelve  to  fifty  parts  of  lead  to  one  of  antimony ;  a  flexible 
alloy  is  obtained,  resembling  lead,  but  somewhat  harder,  and  which 
is  rolled  into  sheets  for  sheathing  ships.  Six  parts  of  lead  and  one 
of  antimony  are  used  for  the  large  soft  printers'  types,  which  will 
bend  slightly,  but  are  considerably  harder  than  the  foregoing ;  and 
three  parts  of  lead  and  one  of  antimony  are  employed  for  the  small- 
est types,  that  are  very  hard  and  Brittle,  and  will  not  bend  at  all ; 
antimony  being  the  more  expensive  metal,  is  used  in  the  smallest 
quantity  that  will  suffice. 

In  this  alloy  the  antimony  fulfills  another  service  besides  that  of 
imparting  hardness :  antimony  somewhat  expands  on  cooling, 


CHARACTERS   OF   METALS   AND   ALLOYS.  211 

'*•  \ 

whereas  lead  contracts  very  much,  and  the  antimony,  therefore, 
within  certain  limits,  compensates  for  this  contraction,  and  causes 
the  alloy  to  retain  the  full  size  of  the  moulds. 

Sometimes,  from  motives  of  economy,  the  neighboring  parts  of 
machinery  are  not  wrought  accurately  to  correspond  one  with  the 
other,  but  lead  is  poured  in  to  fill  up  the  intermediate  space,  and . 
to  make  contact ;  as  around  the  brass  nuts  in  the  heads  of  some 
screw  presses,  in  the  guides  or  followers  for  the  same,  and  some 
other  parts  of  eif her  temporary  or  permanent  machinery.  Anti- 
mony is  quite  essential  in  all  these  easels  to  prevent  the  contraction 
the  lead  alone  would  sustain,  and  which  would  defeat  the  intended 
object,  as  the  metal  would  otherwise  become  smaller  than  the  space 
to  be  filled. 

A  little  tin  is  commonly  introduced  into  types,  and  likewise  cop- 

Eer  in  minute  quantity ;  iron  and  bismuth  are  also  spoken  of;  the 
ist  is  said  to  be  employed  on  account  of  its  well-known  property 
of  expanding  in  cooling,  so  as  to  cause  the  types  to  swell  in  the 
mould,  and  copy  the  face- of  the  letter  more  perfectly,  but  although 
I  find  bismuth  to  have  been  thus  used  it  appears  to  be  neither 
common  nor  essential  in  printing-types. 

The  difference  in  specific  gravity  between  lead  and  antimony 
constantly  interferes,  and  unless  the  type  metal  is  frequently  stirred, 
the  lead,  from  being  the  heavier  metal,  sinks  to  the  bottom,  and  the 
antimony  is  disproportionally  used  from  the  surface. 

In  the  above  examples,  the  differences  arising  from  the  propor- 
tions appear  intelligible  enough,  as  when  the  soft  lead  prevails,  the 
mixture  is  much  like^he  lead ;  and  as  the  hard,  brittle  antimony  is 
increased,  the  alloy  becomes  hardened,  and  more  brittle :  with  the 
proportion  of  four  to  one,  the  fracture  is  neither  reluctant  like  that 
of  lead,  nor  foliated  like  antimony,  but  assumes  very  nearly  the 
grain  and  color  of  some  kinds  of  steel  and  cast-iron.  In  like  man- 
ner, when  tin  and  lead  are  alloyed,  the  former  metal  imparts  to  the 
mixture  some  of  its  hardness,  whiteness,  and  fusibility,  in  propor- 
tion to  its  quantity ;  as  seen  in  the  various  qualities  of  pewter,  in 
which  however  copper,  and  sometimes  zinc  or  antimony  are  found. 
The  same  agreement  is  not  always  met  with ;  as  nine  parts  of 
copper,  which  is  red,  and  one  part  of  tin,  which  is  white,  each  very 
malleable  and  ductile  metals,  make  the  tough,  rigid  metal  used  in 
brass  ordnance,  from  which  it  obtains  its  modern  name  of  gun- 
metal,  but  which  neither  admits  of  rolling  nor  drawing  irito  wire ; 
the  same  alloy  is  described  by  Pliny  as  the  soft  bronze  of  his  day. 
The  continual  addition  of  the  tin,  the  softer  metal,  produces  a 
gradual  increase  of  hardness  in  the  mixture ;  with  about  one-sixth 
of  tin  the  alloy  assumes  its  maximum  hardness  consistent  with  its 
application  to  mechanical  uses ;  with  one-fourth  to  one-third  tin  it 
becomes  highly  elastic  and  sonorous,  and  its  brittleness  rather  than 
its  hardness  is  greatly  increased. 

When  the  copper  becomes  two,  and  the  tin  one  part,  the  alloy  is 
so  hard  as  not  to  admit  of  being  cut  with  steel  tools,  but  crumbles 


212  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

under  their  action ;  when  struck  with  a  hammer  or  even  suddenly- 
warmed  it  flies  in  pieces  like  glass,  and  clearly  shows  a  structure 
highly  crystalline,  instead  of  malleable.  The  alloy  has  no  trace  of 
the  red  color  of  the  copper,  but  it  is  quite  white,  susceptible  of  an 
exquisite  polish,  and  being  little  disposed  to  tarnish,  it  is  most  per- 
fectly adapted  to  the  reflecting  speculums  of  telescopes  and  other 
instruments,  for  which  purpose  it  is  alone  used. 

Copper,  when  combined  in  the  same  proportions  with  a  different 
metal,  also  light-colored  and  fusible,  namely,  two  parts  of  copper, 
with  one  of  zinc,  (which  latter  metal  is  of  a  bluish-white,  and  crys- 
talline, whereas  tin  is  very  ductile,)  makes  an  alloy  of  entirely  oppo- 
site character  to  the  speculum  metal ;  namely,  the  soft  yellow  brass, 
which  becomes  by  hammering  very  elastic  and  ductile,  and  is  very 
easily  cut  and  filed. 

Again,  the  same  proportions,  namely,  two  parts  of  copper  and 
one  of  lead,  make  a  common  inferior  metal,  called  pot-metal,  or 
cock-metal,  from  its  employment  in  those  respective  articles.  This 
alloy  is  much  softer  than  brass,  and  hardly  possesses  malleability ; 
when,  for  example,  the  beer-tap  is  driven  into  the  cask,  immediately 
after  it  has  been  scalded,  the  blow  occasionally  breaks  it  in  pieces, 
from  its  reduced  cohesion. 

Another  proof  of  the  inferior  attachment  of  the  copper  and  lead 
exists  in  the  fact  that,  if  the  moulds  are  opened  before  the  castings 
are  almost  cold  enough  to  be  handled,  the  lead  will  ooze  out  and 
appear  on  the  surface  in  globules.  This  also  occurs  to  a  less  extent 
in  gun-metal,  which  should  not  on  that  account  be  too  rapidly  ex- 
posed to  the  air ;  or  the  tin  strikes  to  the  sui&ce,  as  it  is  called,  and 
makes  it  particularly  hard  at  those  parts,  from  the  proportional  in- 
crease of  the  tin.  In  casting  large  masses  of  gun-metal,  it  frequently 
happens  that  little  hard  lumps,  consisting  of  nearly  half  tin,  work 
up  to  the  surface  of  the  runners  or  pouring  places,  during  the  time 
the  metal  is  cooling. 

In  brass,  this  separation  scarcely  happens,  and  these  moulds  may 
be  opened  whilst  the  castings  are  red  hot,  without  such  occurrence ; 
from  which  it  appears  that  the  copper  and  zinc  are  in  more  perfect 
chemical  union  than  the  alloys  of  copper  with  tin  and  with  lead. 

MALLEABILITY  AND  DUCTILITY  OF  ALLOYS. — The  malleability 
and  ductility  of  alloys  are  in  a  great  measure  referable  to  the  de- 
grees in  which  the  metals  of  which  they  are  respectively  composed, 
possess  these  characters. 

Lead  and  tin  are  malleable,  flexible,  ductile,  and  inelastic  whilst 
cold,  but  when  their  temperatures  much  exceed  about  half  way  to- 
wards their  melting  heats  they  are  exceedingly  brittle  and  tender, 
owing  to  their  reduced  cohesion. 

The  alloys  of  lead  and  tin  partake  of  the  general  nature  of  these 
two  metals-;  they  are  flexible  when  cold,  even  with  certain  addi- 
tions of  the  brittle  metals,  antimony  and  bismuth,  or  of  the  fluid 
metal  mercury ;  but  they  crumble  with  a  small  elevation  of  tempera- 
ture, as  these  alloys  melt  at  a  lower  degree  than  either  of  their 


CHARACTERS   OF   METALS  AND  ALLOYS.  213 

components,  to  which  circumstance  we  are  indebted  for  the  tin 
solders. 

Zinc,  when  cast  in  thin  cakes,  is  somewhat  brittle  when  cold,  but 
its  toughness  is  so  far  increased  when  it  is  raised  to  about  300°  F. 
that  its  manufacture  into  sheets  by  means  of  rollers  is  then  admissi- 
ble ;  it  becomes  the  malleable  zinc,  and  retains  the  malleable  and 
ductile  character,  in  a  moderate  degree,  even  when  cold,  but  in 
bending  rather  thick  plates  it  is  advisable  to  warm  them  to  avoid 
fracture ;  when  zinc  is  remelted,  it  resumes  its  original  crystalline 
condition.  It  is  considered  that  most  of  the  sheet  zinc  contains  a 
very  little  lead. 

Zinc  and  lead  will  not  combine  without  the  assistance  of  arsenic, 
unless  the  lead  is  in  very  small  quantity.  The  arsenic  makes  this 
and  other  alloys  very  brittle,  and  it  is  besides  dangerous  to  use. 
Zinc  and  tin  make,  as  may  be  supposed,  somewhat  hard  and  brittle 
alloys,  but  none  of  the  zinc  alloys,  except  that  with  copper  to  con- 
stitute brass,  are  much  used. 

Gold,  silver,  and  copper,  which  are  greatly  superior  in  strength 
to  the  fusible  metals  above  named,  may  be  forged  either  when  red- 
hot  or  cold,  as  soon  as  they  have  been  purified  from  their  earthy 
matters,  and  fused  into  ingots ;  and  the  alloys  of  gold,  silver,  and 
copper,  are  also  malleable,  either  red-hot  or  cold. 

Fine,  or  pure  gold  and  silver,  are  but  little  used  alone.  The 
alloy  is  in  many  cases  introduced  less  with  the  view  of  depreciating 
their  value  than  of  adding  to  their  hardness^tenacity,  and  duc- 
tility. The  processes  which  the  most  severely  test  these  qualities, 
namely,  drawing  the  finest  wires,  and  beating  gold  and  silver  leaf, 
are  not  performed  with  the  pure  metals,  but  gold  is  alloyed  with 
copper  for  the  red  tint,  with  silver  for  the  green,  and  with  both  for 
intermediate  shades.  Silver  is  alloyed  with  copper  only,  and  when 
the  quantity  is  small  its  color  suffers  but  slightly  from  the  addition, 
although  its  working  qualities  are  greatly  improved,  pure  silver 
being  little  used. 

The  alloys  of  similar  metals  having  been  considered,  it  only  re- 
mains to  observe  that  when  dissimilar  metals  are  combined,  as 
those  of  the  two  opposite  groups ;  namely,  the  fusible  lead,  tin,  or 
zinc,  with  the  less  fusible  copper,  gold,  and  silver,  the  malleability 
of  the  alloys  when  cold  is  less  than  that  of  the  superior  metal ; 
and  when  heated  barely  to  redness,  they  fly  in  pieces  under  the 
hammer ;  and,  therefore,  brass,  gun-metal,  etc.,  when  red-hot,  must 
be  treated  with  precaution"  and  tenderness.  It  will  be  remembered 
the  action  of  rollers  is  more  regular  than  that  of  the  hammer,  and 
soon  gives  rise  to  the  fibrous  character,  which,  so  far  as  it  exists 
in  metals,  is  the  very  element  of  strength  when  it  is  uniformly 
distributed  throughout  their  substance.  This  will  be  seen  by  the 
inspection  of  the  relative  degrees  of  cohesion  possessed  by  the  same 
metal  when  in  the  conditions  of  the  casting,  sheet,  or  wire,  shown 
by  the  table,  and  to  which  quality  or  the  tenacity  of  the  alloys  we 
shall  now  devote  a  few  lines. 


214 


THE   PRACTICAL   METAL-  WORKER'S  ASSISTANT. 


STRENGTH  OR  COHESION  OF  ALLOYS.  —  The  strength  or  cohesion 
of  the  alloys  is  in  general  greatly  superior  to  that  of  any  of  the 
metals  of  which  they  are  composed.  For  example,  on  comparing 
some  of  the  numbers  of  the  table  on  pages  206  and  208,  it  will  be 
seen  that  the  relative  weights,  which  tear  asunder  a  bar  one  inch 
square  of  the  several  substances,  stand  as  follows,  —  all  the  num- 
bers being  selected  from  Muschenbroek's  valuable  investigations, 
so  that  it  may  be  presumed  the  same  metals,  and  also  the  same 
means  of  trial,  were  used  in  every  case. 


Cast  Metals. 


Barbary  Copper,   22,570  Ibs. 
Japan          —         20,272   « 


English  Block  Tin,  6,650 

Do.               —  5,322 

Banea  Tin,  3,679 

Malacca  Tin,  3,211 


Alloys. 

10  Copper,  1  Tin,  32,093  Ibs. 

8  _     —  36,088  ' 

6  —     —  44.071 

4  _  —  35,739 
2  _  _  1,017 
1  _  _  725 

The  inspection  of  these  numbers  is  highly  conclusive,  and  it 
shows  that  the  engineer  agrees  with  theory  and  experiment  in 
selecting  the  proportion  6  to  1  as  the  strongest  alloy  ;  and  that  the 
philosopher,  in  choosing  the  most  reflective  mixture,  employs  the 
weakest  but  one, — its  strength  being  only  one-third  to  one-sixth 
that  of  the  tin,  or  one-twentieth  that  of  the  copper,  which  latter 
constitutes  two-thirds  its  amount. 

It  is  much  to  be  regretted  that  the  valuable  labors  of  Muschen- 
broe'k  have  not  b^n  followed  up  by  other  experiments  upon  the 
alloys  in  more  general  use.  One  curious  circumstance  will  be  ob- 
served, however,  in  those  which  are  given,  namely,  that  in  the 
following  alloys,  which  are  the  strongest  of  their  respective  groups, 
the  tin  is  always  four  times  the  quantity  of  the  other  metal ;  and 
they  all  confirm  the  circumstance  of  the  alloys  having  mostly  a 
greater  degree  of  cohesion  than  the  stronger  of  their  component 
metals. 

Alloys.  Cast  Metals. 


4  English  Tin, 

4  BancaTin, 
4       —      — 

4  English  Tin, 


1    Lend, 
1    Antimony, 
1    Bismuth, 
1    Goslar  Zinc, 
1   Antimony, 


10,607  Ibs. 
13,480    " 
16,692    " 
10,258    "* 
11,323    " 


•  Lead,  885  Ibs. 

•  Antimony,          1,060    " 

•  Zinc,  2,689    " 

•  Bismuth,  3,008    " 
.  Tin,      3,211  to  6,650    " 


Fig.  118  represents  a  very  ingenious  instrument,  denominated  an 
alloy-balance.  It  is  intended  for  weighing  those  metals  the  propor- 
tions of  which  are  stated  decimally  :  its  principle,  which  is  so  simple 
as  hardly  to  require  explanation,  depends  upon  the  law  that  weights 
in  equilibrium  are  inversely  as  their  distances  from  the  point  of 
support. 

For  weighing  out  any  precise  number  of  pounds  or  ounces,  in 
the  common  way,  the  arms  of  the  ordinary  scale-beam  are  made  as 


*  This,  in  truth,  is  an  exception  ;  it  barely  equals  in  strength  the  alloys 
with  8  and  2  parts  of  tin  to  1  of  zinc,  but  is  superior  to  that  of  equal  parts. 
It  corroborates  the'great  increase  of  strength  in  alloys  generally. 


CHARACTERS   OF   METALS   AND   ALLOYS. 


215 


nearly  equal  as  possible ;  so  that  the  weights,  and  the  articles  to  be 
weighed,  maybe  made  to  change  places,  in  proof  of  the  equality  of  the 

Fig.  118. 


instrument.  But  to  weigh  out  an  alloy,  say  of  17  parts  tin  and  83 
copper,  unless  the  quantities  were  either  17  and  83  Ibs.  or  ounces, 
would  require  a  little  calculation. 

This  is  obviated,  if  the  point  of  suspension  a,  of  the  alloy-balance, 
which  is  hung  from  any  fixed  support  b,  is  adjusted  until  the  arms 
are  respectively  as  17  to  83 ;  and  for  this  purpose  the  half  of  the 
beam  is  divided  into  fifty  equal  parts  numbered  from  the  one  end ; 
and,  prior  to  use,  it  only  remains  to  adjust  the  weight,  w,  so  as  to 
place  the  empty  balance  in  equilibrium.  A  quantity  of  copper, 
rudely  estimated,  having  been  suspended  from  the  short  arm  of  the 
balance,  the  proportionate  quantity  of  the  tin  will  be  denoted  with 
critical  accuracy,  when,  by  its  gradual  addition,  the  beam  is  exactly 
restored  to  the  horizontal  line ;  should  the  alloy  consist  of  three  or 
more  parts,  the  process  of  weighing  is  somewhat  more  complex. 

The  annexed  table  was  calculated  by  the  author,  for  converting  the 
proportions  of  alloys  stated  decimally,  into  avoirdupois  weight.  It 
applies  with  equal  facility  to  alloys  containing  two  or  many  compo- 
nents, so  as  to  bring  them  readily  within  the  power  of  ordinary  scales. 


216 


THE   PKACTICAL   METAL-WORKER^  ASSISTANT. 


TABLE   FOR   CONVERTING   DECIMAL   PROPORTIONS 
Into  Divisions  of  the  Pound  Avoirdupois. 


Decimal. 

oz.     dr. 

Decimal. 

oz.      dr. 

Decimal. 

oz.     dr. 

Decimal. 

oz.     dr. 

.78 

1 

13.28 

2     1 

25.78 

•4      1 

38.28 

6     1 

1.56 

i 

14.06 

2    2 

26.56 

4     2 

39.06 

6     2 

2.34 

f 

14.84 

2    3 

27.34 

4     3 

39.84 

6     8 

3.12 

4 

15.62 

2    4 

28.12 

4     4 

40.62 

6     4 

3.91 

5 

16.41 

2    5 

28.91 

4     5 

41.41 

6     5 

4.69 

6 

17.19 

2     6 

29.69 

4     6 

42.19 

6      6 

5.47 

7 

17.97 

2    7 

30.47 

4     7 

42.97 

6     7 

6.25 

1   0 

18.75 

3     0 

31.25 

5     0 

43.75 

7     0 

7.03 

1   1 

19.53 

3     1 

32.03 

5     1 

44.53 

7     1 

7.81 

1   2 

20.31 

3    2 

32.81 

5     2 

45.31 

7     2 

8.59 

1   3 

21.09 

3    3 

33.59 

5     8 

46.09 

7     3 

9.37 

1   4 

21.87 

3    4 

34.37 

5     4 

46.87 

7     4 

10.16 

1   5 

22.66 

3    5 

35.16 

5     5 

47.66 

7     5 

10.94 

1   6 

23.44 

3     6 

35.94 

5     6 

48.44 

7     6 

11.72 

1   7 

24.22 

3    7 

36.72 

5     7 

49.22 

7     7 

12.50 

2   0 

25.06 

4    0 

37.50 

6     0 

50.00 

8     0 

Application  of  the  Table. 

The  Chinese  Packfong,  similar  to  our  German  silver,  is  said  to 
consist  of— 

40.4  parts  of  Copper  "1  f  6  oz.  4  drams,  nearly. 

25.4       —      Zinc  .     ,  4  —  0     —     full. 

31.6      -      Nickel  f  equivalent  to  j  5_1     _     neapl 

2.6      —      Iron  0  —  3     —     full. 


100.0  parts 


16  oz.  0 


Avoird's. 


All  nice  attempts  at  proportion  are,  however,  entirely  futile,  un- 
less the  metals  are  perfectly  pure;  for  example,  it  is  a  matter  of 
common'  observation  that  for  speculums  a  variable  quantity  of  from 
seven  and  a  half  to  eight  and  a  half  ounces  of  tin  is  required  for 
the  exact  saturation  of  every  pound  of  copper,  and  upon  which 
saturation  the  efficiency  of  the  compound  depends ;  bells  of  exactly 
similar  quality  sometimes  thus  require  the  dose  of  tin  to  vary  from 
three  and  a  half  to  five  ounces  to  the  pound  of  copper,  according 
to  the  qualities  of  the  metals. 

The  variations  in  the  purity  of  the  metals  obtained  from  different 
localities  are  abundantly  demonstrated  by  the  disagreement  in  the 
cohesive  strengths  of  the  two  in  question,  more  particularly  the  tin, 
as  seen  on  page  214,  and  which  can  be  only  ascribed  to  their  re- 
spective amounts  of  impurity.  Any  other  supposition  than  the 


CHARACTERS   OF   METALS   AND   ALLOYS.  217 

presence  of  foreign  matter,  would  necessarily  go  to  disprove  the 
fact  of  the  metals  being  simple  bodies,  and  therefore  strictly  alike 
when  absolutely  pure,  wheresoever  they  may  have  been  obtained. 

FUSIBILITY  OF  ALLOYS. — In  concluding  this  slight  view  of  some 
of  the  general  characters  of  alloys,  it  remains  to  consider  the  influ- 
ence of  heat,  both  as  an  agent  in  their  formation  and  as  regards 
the  degree  in  which  it  is  required  for  their  after-fusion ;  the  lowest 
available  temperature  being  the  most  desirable  in  every  such  case. 

Metals  do  not  combine  with  each  other  in  their  solid  state,  owing 
to  the  influence  of  chemical  affinity  being  counteracted  by  the 
force  of  cohesion.  It  is  necessary  to  liquefy  at  least  one  of  them, 
in  which  case  they  always  unite,  provided  their  mutual  attraction  is 
energetic.  Thus,  brass  is  formed  when  pieces  of  copper  are  put 
into  melted  zinc ;  and  gold  unites  with  mercury  at  common  tem- 
peratures by  mere  contact. 

The  agency  of  mercury  in  bringing  about  triple  combinations  of 
the  metals,  both  with  and  without  heat,  is  also  very  curious  and 
extensive.-  Thus,  in  water-gilding,  the  silver,  copper,  or  gilding 
metal,  when  chemically  clean,  is  rubbed  over  with  an  amalgam 
of  gold  containing  about  eight  parts  of  mercury ;  this  immediately 
attaches  itself,  and  it  is  only  necessary  to  evaporate  the  mercury, 
which  requires  a  very  moderate  heat,  and  the  gold  is  left  behind. 
Water-silvering  is  similarly  accomplished. 

Cast-iron,  wrought-iron,  and  steel,  as  well  as  copper  and  many 
other  metals,  may  be  tinned  in  a  similar  manner.  An  amalgam  of 
tin  and  mercury  is  made  so  as  to  be  soft  and  just  friable ;  the  metal 
to  be  tinned  is  thoroughly  cleaned,  either  by  filing  or  turning,  or 
if  only  tarnished  by  exposure,  it  is  cleaned  with  a  piece  of  emery- 
paper  or  otherwise,  without  oil,  and  then  rubbed  with  a  thick  cloth 
moistened  with  a  few  drops  of  muriatic  acid.  A  little  of  the  amal- 
gam then  rubbed  on  with  the  same  rag,  thoroughly  coats  the  cleaned 
parts  of  the  metal  by  a  process  which  is  described  as  cold-tinning  ; 
other  pieces  of  metal  may  be  attached  to  the  tinned  parts  by  the 
ordinary  process  of  tin-soldering. 

In  making  the  tinned  iron  plates,  the  scoured  and  cleaned  iron 
plates  are  immersed  in  a  bath  of  pure  melted  tin,  covered  with  pure 
tallow,  the  tin  then  unites  with  every  part  of  the  surfaces ;  and  in 
the  ordinary  practice  of  tinning  culinary  vessels  of  copper,  pure  tin 
is  also  used.  The  two  metals,  however,  must  then  be  raised  to  the 
melting  heat  of  tin ;  but  the  presence  of  a  little  mercury  enables 
the  process  to  be  executed  at  the  atmospheric  temperature,  as  above 
explained. 

In  M.  Mallet's  recently  patented  processes  for  the  protection  of 
iron  from  oxidation  and  corrosion,  and  for  the  prevention  of  the 
fouling  of  ships,  one  proceeding  consists  in  covering  the  iron  with 
zinc. 

The  ribs  or  plates  for  iron  ships  are  immersed  in  a  cleansing  bath 
of  equal  parts  of  sulphuric  or  muriatic  acid  and  water,  used  warm ; 
the  works  are  then  hammered,  and  scrubbed  with  emery  or  sand. 


218  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

to  detach  the  scales  and  to  thoroughly  clean  them ;  they  are  then 
immersed  in  a  preparing  bath  of  equal  parts  of  saturated  solutions 
of  muriate  of  zinc  and  sal-ammoniac,  from  which  the  works  are 
transferred  to  a  fluid  metallic  bath,  consisting  of  202  parts  of  mer- 
cury and  1292  parts  of  zinc,  both  by  weight  (being  in  the  proportion 
of  one  atom  of  mercury  to  forty  atoms  of  zinc) ;  to  every  ton  weight 
of  which  alloy,  is  added  about  one  pound  of  either  potassium  or 
sodium  (the  metallic  bases  of  potash  and  soda),  the  latter  being 
preferred.  As  soon  as  the  cleaned  iron  works  have  attained  the 
melting  heat  of  the  triple  alloy,  they  are  removed,  having  become 
thoroughly  coated  with  zinc. 

The  affinity  of  this  alloy  for  iron  is,  however,  so  intense,  and  the 
peculiar  circumstances  of  surface  as  induced  upon  the  iron  presented 
to  it  by  the  preparing  bath  are  such,  that  care  is  requisite  least 
by  too  long  an  immersion  the  plates  are  not  partially  or  wholly 
dissolved.  Indeed  where  the  articles  to  be  covered  are  small,  or 
their  parts  minute,  such  as  wire,  nails  or  small  chain,  it  is  necessary 
before  immersing  them  to  permit  the  triple  alloy  to  dissolve  or 
combine  with  some  wrought-iron,  in  order  that  its  affinity  for  iron 
may  be  partially  satisfied  and  thus  diminished.  At  the  proper 
fusing  temperature  of  this  alloy,  which  is  about  680°  Fahr.,  it  will 
dissolve  a  plate  of  wrought-iron  of  an  eighth  of  an  inch  thick  in  a 
few  seconds. 

The  Palladiumizing  Process. — The  articles  to  be  protected  are  to 
be  first  cleansed  in  the  same  way  as  in  the  case  of  zincing ;  namely, 
by  means  of  the  double  salts  of  zinc  and  ammonia,  or  of  manganese 
and  ammonia ;  and  then  to  be  thisly  coated  over  with  palladium, 
applied  in  a  state  of  amalgam  with  mercury. 

In  the  opinion  of  eminent  chemists  and  metallurgists,  all  the  met- 
als, even  the  most  refractory  which  nearly,  or  quite  refuse  to  melt 
in  the  crucible  when  alone,  will  gradually  run  down  when  sur- 
rounded by  some  of  the  more  fusible  metals  in  the  fluid  state ;  in  a 
manner  similar  to  the  solution  of  the  metals  in  mercury,  as  in  the 
amalgams,  or  the  solutions  of  solid  salts  in  water.  The  surfaces  of 
the  superior  metals  are,  as  it  were,  dissolved,  washed  down,  or  re- 
duced to  the  state  of  alloys,  layer  by  layer,  until  the  entire  mass  is 
liquefied. 

Thus  nickel,  although  it  barely  fuses  alone,  enters  into  the  com- 
position of  German  silver  by  aid  of  the  copper,  and  whilst  it  gives 
whiteness  and  hardness,  it  also  renders  the  mixture  less  fusible. 
Platinum  combines  very  readily  with  zinc,  arsenic,  and  also  with 
tin  and  other  metals ;  so  much  so  that  it  is  dangerous  to  melt  either 
of  those  metals  in  a  platinum  spoon ;  or  to  solder  platinum  with 
common  tin  solder,  which  fuses  at  a  very  low  temperature  :  although 
platinum  is  constantly  soldered  with  fine  gold,  the  melting  point  of 
which  is  very  high  in  the  scale.  Again,  the  circumstances  that 
some  of  the  fusible  bismuth  alloys  melt  below  the  temperature  of 
boiling  water,  or  at  less  than  half  the  melting  heat  of  tin,  their  most 
fusible  ingredient,  show  that  the  points  of  fusion  of  alloys  are 


CHARACTERS  OF   METALS  AND  ALLOYS.  219 

equally  as  difficult  of  explanation  or  generalization  as  many  other 
of  the  anomalous  circumstances  concerning  them. 

This  much,  however,  may  be  safely  advanced,  that  alloys,  without 
exception,  are  more  easily  fused  than  the  superior  metal  of  which 
they  are  composed ;  and  extending  the  same  view  to  the  relative 
quantities  of  the  components,  it  may  be  observed  that  the  hard 
solders  for  the  various  metals  and  alloys,  are  in  general  made  of 
the  self-same  material  which  they  are  intended  to  join,  but  with  small 
additions  of  the  more  fusible  metals.  The  solder  should  be,  as 
nearly  as  practicable,  equal  to  the  metal  on  which  it  is  employed, 
in  hardness,  color,  and  every  property  except  fusibility ;  in  which 
it  must  excel  just  to  an  extent  that,  when  ordinary  care  is  used, 
Avill  avoid  the  risk  of  melting  at  the  same  time,  both  the  object  to 
be  soldered  and  likewise  the  softer  alloy  or  solder  by  which  it  is 
intended  to  unite  its  parts. 

It  would  appear  as  if  every  example  of  soldering  in  which  a  more 
fusible  alloy  is  interposed,  were  also  one  of  superficial  alloying. 
Thus,  when  two  pieces  of  iron  are  united  by  copper,  used  as  a  sol- 
der, it  seems  to  be  a  natural  conclusion  that  each  surface  of  the  iron 
becomes  alloyed  with  the  copper :  and  that  the  two  alloyed  surfaces 
are  held  together  from  their  particles  having  been  fused  in  contact, 
and  run  into  one  film.  It  is  much  the  same  when  brass  or  spelter 
solder  is  used,  except  that  triple  alloys  are  then  formed  at  the  sur- 
faces of  the  iron,  and  so  with  most  other  instances  of  soldering. 

And  in  cases  where  metallic  surfaces  are  coated  by  other  metals, 
the  latter  being  at  the  time  in  a  state  of  fusion,  as  in  tinned-iron 
plates  and  silvered  copper ;  may  it  not  also  be  conceived,  that  be- 
tween the  two  exterior  surfaces,  which  are  doubtless  the  simple 
metals,  a  thin  film  of  an  alloy  compounded  of  the  two  does  in  reality 
exist  ?  And  in  those  cases  in  which  the  coating  is  laid  on  by  the 
aid  of  mercury,  and  without  heat,  the  circumstances  are  very  sim- 
ilar, as  the  fluidity  of  mercury  is  identical  with  the  ordinary  state 
of  fusion  of  other  metals,  although  the  latter  require  higher  tem- 
peratures than  that  of  our  atmosphere. 

When  portions  of  the  same  metal  are  united  by  partial  fusion, 
and  without  solder,  as  in  the  process  described  as  burning  together, 
and  more  recently  known  as  the  "  autogenous"  mode  of  soldering, 
no  alloy  is  formed,  'as  the  metals  simply  fuse  together  at  their 
surfaces. 

Neither  can  it  be  supposed  that  any  formation  of  alloy  can 
occur,  where  the  one  metal  is  attached  to  the  other  by  the  act  of 
burnishing  on  with  heat,  as  in  making  gilt  wire,  but  without  a 
temperature  sufficient  to  fuse  either  of  the  metals.  The  union  in 
this  case  is  probably  mechanical,  and  caused  by  the  respective  par- 
ticles or  crystals  of  the  one  metal  being  forced  into  the  pores  of 
the  other,  and  becoming  attached  by  a  species  of  entanglement, 
similar  to  that  which  may  be  conceived  to  exist  throughout  solid 
bodies.  This  process,  almost  more  than  any  other  in  common  use, 
requires  that  the  metals  should  be  perfectly  or  chemically  clean  ; 


220  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

for  which  purpose  they  are  scraped  quite  bright  before  they  are 
burnished  together,  so  that  the  junction  may  be  next  approaching 
to  that  of  solids  generally. 

And,  lastly,  when  metals  are  deposited  upon  other  metals  by 
chemical  or  electrical  means,  the  addition  frequently  appears  to  be 
a  detached  sheath,  and  which  is  easily  removed ;  indeed,  unless  the 
metal  to  be  coated  is  chemically  clean,  and  that  various  attendant 
circumstances  are  favorable,  the  sound  and  absolute  union  of  the 
two  does  not  always  happen,  even  when  carefully  aimed  at. 

It  is  time,  however,  that  we  proceed  to  the  description  of  the 
methods  of  forming  the  ordinary  alloys,  the  subject  of  the  succeed- 
ing matter. 


CHAPTER  XIY. 
MELTING  AND  MIXING  THE  METALS. 

THE  VAEIOUS  FURNACES,  ETC.,  FOR  MELTING  THE  METALS. — 
The  subject  upon  which  we  have  now  to  enter  consists  of  two 
principal  divisions,  namely,  the  melting  and  combining  of  the  met- 
als, and  the  formation  of  the  moulds  into  which  the  fluid  metals 
are  to  be  poured.  In  the  foundry  the  two  processes  are  generally 
carried  on  together,  so  that  by  the  time  the  mould  is  completed, 
the  metal  may  be  ready  to  be  poured  into  it ;  but  as  in  conveying 
these  several  particulars  the  one  process  must  have  precedence,  I 
propose  to  commence  with  the  means  ordinarily  employed  in  melt- 
ing and  mixing  the  metals,  in  order  to  associate  more  closely  all 
that  concerns  the  alloys.  In  accordance  with  ordinary  practice, 
the  formation  of  the  moulds  will  be  described  whilst  the  metals 
may  be  supposed  to  be  in  course  of  fusion ;  the  concluding  re- 
marks will  be  on  pouring,  or  filling  the  moulds,  the  act  strictly 
speaking  of  casting,  and  which  completes  the  work. 

The  fusible  metals,  or  those  not  requiring  the  red-heat,  are  melted 
when  in  small  quantities  in  the  ordinary  plumber's  ladle  over  the 
fire ;  otherwise  larger  cast-iron  ladles  or  pans  aire  used,  beneath 
which  a  fire  is  lighted  ;%for  very  large  quantities  and  various  manu- 
facturing purposes,  such  as  casting  sheet-lead,  and  lead  pipe,  and 
also  for  type-founding,  the  metals  are  melted  in  iron  pans  set  in 
brickwork,  with  a  fire-place  and  ash-pit  beneath,  much  the  same  as 
an  ordinary  laundry  copper,  and  the  metals  are  removed  from  the 
pans  with  ladles. 

The  pewterers  and  some  others  call  the  melting  pan  a  pit, 
although  it  is  erected  entirely  above  the  floor  ;  and  as  their  meltings 
are  made  up  in  great  part  of  old  metal,  which  is  sometimes  wet  or 
damp,  they  have  iron  doors  to  enclose  the  mouth  of  the  Dan,  in 


MELTIXG   AXD   MIXING   THE   METALS. 


221 


case  any  of  the  metal  should  be  splashed  about  from  the  moisture 
reaching  the  fluid  metal. 

Antimony,  copper,  gold,  silver,  and  their  alloys,  are  for  the  most 
part  melted  in  crucibles  .within  furnaces  similar  to  the  kind  used 
by  the  brass  founders,  which  is  represented  at  a,  Fig.  119 ;  the  en- 
tire figure  represents  the  imaginary  section,  of  a  brass  foundry 
with  the  moulding,  trough,  b,  for  the  sand  on  the  side  opposite  the 
furnace,  the  pouring  or  spill  trough,  c,  in  the  centre,  and  the  core 
oven  d,  which  is  usually  built  in  the  wall  close  against  one  of  the 
flues ;  but  these  matters  will  be  described  hereafter. 

The  brass  furnace  is  usually  built  within  a  cast-iron  cylinder, 
about  20  to  24  inches  diameter  and  30  to  40  inches  high,  which  is 
erected  over  an  ash-pit  arrived  at  through  a  loose  grating  on  a 
level  with  the  floor  of  the  foundry.  The  mouth  of  the  furnace 

Fig.  119. 


stands  about  8  or  10  inches  above  the  floor,  and  its  central  aper- 
ture is  closed  with  a  plate  now  usually  of  iron,  although  still 
called  a  tile ;  the  inside  of  the  furnace  is  contracted  to  about  10 
inches  diameter  by  fire-bricks  Bet  in  Stourbridge  clay,  except  a 
small  aperture  at  the  back  about  4  or  5  inches  square,  leading  into 
the  chimney. 

There  are  generally  three  or  four  such  furnaces  standing  in  a  row, 
and  separate  flues  proceed  from  all  into  the  great  chimney  or  stack, 
the  height  of  which  varies  from  about  twenty  to  forty  feet,  and  up- 
wards, the  more  lofty  it  is  the  greater  the  draught ;  every  furnace 
has  also  a  damper  to  regulate  its  individual  fire. 

It  is  quite  essential  for  constant  work  to  have  several  furnaces, 
in  order  that  one  or  two  may  be  in  use,  whilst  the  others  lie  idle  to 
allow  of  their  being  repaired,  as  they  rapidly  burn  away,  and  when 
the  space  around  the  crucible  exceeds  about  2  or  3  inches,  the  fuel 
is  consumed  unnecessarily  quick ;  the  furnace  is  then  contracted  to 
its  original  size  with  a  dressing  of  road  drift  and  water  applied 


222  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

like  mortar,  the  fire  is  lighted  immediately,  and  urged  vigorously 
to  glaze  the  lining.  Eoad  drift,  or.  the  scrapings  of  the  ordinary 
turn-pike  roads,  principally  silex  and  alumina,  is  often  used  for  the 
entire  lining  of  the  furnaces.  The  refuse  sand  from  the  glass 
grinders,  which  contain  flint  glass,  is  also  used  for  repairing  them. 
It  is  also  convenient  to  have  several  furnaces  for  another  reason, 
as  when  a  single  casting  requires  more  than  the  usual  charge  of  one 
furnace,  namely,  about  40  to  60  Ibs.,  two  or  more  fires  can  be  used. 
When  the  quantity  of  brass  to  be  melted  exceeds  the  charge  of 
three  or  four  ordinary  air  furnaces,  the  common  blast  furnace  for 
iron  is  sometimes  used  as  a  temporary  expedient;  the  practice, 
however,  is  bad,  as  it  causes  great  oxidation  and  waste.  The 
greatest  quantities  of  metal,  as  for  large  bells,  statues,  and  ordnance, 
amounting  sometimes  to  several  tons,  are  commonly  melted  in  re- 
verberatory  furnaces. 

The  furnaces  used  by  the  gold  and  silver  refiners  are  in  many 
respects  similar  to  the  brass  burnace  a,  Fig.  119,  but  they  are  built 
as  a  stunted  wall  along  one  or  more  sides  of  the  refinery,  and  en- 
tirely above  the  floor  of  tbe  same.  The  several  apertures  for  the 
fuel  and  crucible  are  from  9  to  16  inches  square,  or  else  cylindri- 
cal, and  12  to  20  inches  deep  ;  the  front  edge  of  the  wall  is  horizon- 
tal, and  stands  about  30  inches^from  the  ground,  but  from  the 
mouth  of  the  furnace  backwards  it  is  inclined  -at  an  angle  of  about 
20  to  40  degrees,  so  that  the  tiles,  or  the  iron  covers  of  the  furnace, 
lie  at  that  angle.  A  narrow  ledge  cast  in  the  solid  with  the  iron 
plates  covering  the  upper  surface  of  the  wall,  retains  the  tiles  in 
their  position. 

The  small  kinds  of  air  furnaces  are  of  easy  construction,  but  as  a 
temporary  expedient  almost  any  close  fire  may  be  used,  including 
some  of  the  German  stoves  and  hot-air  stoves,  that  is  for  melting 
brass,  which  is  more  fusible  than  copper ;  although  it  is  much  the 
most  convenient  that  the  fire  be  open  at  the  top,  so  that  the  con- 
tents of  the  crucible  may  be  seen  without  the  necessity  for  its  re- 
moval from  the  fire.  Such  stoves,  however,  radiate  heat  in  a  some- 
what inconvenient  manner,  and  to  a  much  greater  extent  than  the 
various  portable  furnaces,  most  of  which  are  lined  with  fire-brick 
or  clay ;  the  lining  concentrates  the  heat  and  economizes  the  fuel. 
Many  of  these  portable  furnaces  answer  not  only  for  copper  but 
also  for  iron,  when  they  have  a  good  draft ;  it  may  happen,  however, 
that  the  chemical  furnaces  are  equally  as  inaccessible  to  the  ama- 
teur as  those  expressly  constructed  for  the  metals. 

Country  blacksmiths,  who  are  frequently  called  upon  to  practice 
many  trades,'  sometimes  melt  from  ten  to  fifteen  pounds  of  brass  in 
the  ordinary  forge  fire,  but  there  is  considerable  risk  of  cracking 
the  earthen  crucible  at  the  point  exposed  to  the  blast ;  a  wrought- 
iron  pot  is  sometimes  resorted  to,  but  this  is  not  very  enduring,  as 
the  brass  will  soon  cause  it  to  burn  into  holes  and  leak. 

OBSERVATIONS  ON  THE  MANAGEMENT  OF  THE  FURNACE,  AND  ON 
MIXING  ALLOYS. — The  fuel  for  the  brass  furnace  is  always  hard 


MELTING  AND   MIXING  THE   METALS.  223 

coke,  which  is  prepared  in  ovens  and  broken  into  lumps  about  the 
size  of  hens'  eggs :  in  lighting  the  fire,  a  bundle  of  shavings,  chips, 
of  cork,  or  any  similar  combustible,  is  first  thrown  in  and  ignited, 
and  then  some  coke  or  charcoal  is  added.  It  is.  also  usual  to  put 
the  pot  in  the  fire  at  an  early  stage,  and  with  its  mouth  down- 
wards: by  this  means  the  thin  edge  which  admits  the  most  easily, 
of  expansion  gets  hot  first,  and  the  heat  plays  within  the  crucible, 
so  as  to  warm  it  gradually :  it  is  not  reversed  until  the  whole  is  red 
hot :  putting  it  in  bottom  downwards  would  be  almost  certain  to 
cause  it  to  crack. 

The  pot  is  now  bedded  upon  the  fuel,  and  the  brass-founder, 
whilst  making  up  the  fire,  puts  an  iron  cover  with  a  long  central 
handle  over  the  mouth  of  the  pot,  to  prevent  the  small  cokes  which 
are  now  thrown  on  from  entering  the  same.  Next,  the  charge  of 
metal  is  put  in  the  crucible*,  and  three  or  four  large  pieces  of  coke 
are  placed  across  the  mouth  of  the  pot ;  the  tile  is  put  on  the  fur- 
nace, the  -damper  is  then  adjusted  to  heat  the  crucible  quickly,  and 
the  whole  is  left  to  itself  until  the  metal  is  run  down. 

The  gold  and  silver  refiners  and  jewelers  manage  their  furnaces 
much  in  the  same  way,  except  that  they  support  the  crucible  upon 
a  hollow  earthen  stand  placed  08  the  fire-bars  to  catch  any  leakage, 
and  also  put  an  earthen  cover  over  its  mouth.  They  generally  use 
coke,  although  charcoal  is  a  purer  fuel,  and  is  laid  upon  the  fluid 
metals  to  prevent  oxidation.  The  above,  and  the  so-called  blue 
pots,  or  black-lead  pots,  are  not  burned  until  they  are  put  into  the 
fire  for  use  ;  but  the  Hessian  pots,  the  English  brown  or  clay  pots, 
thev  Cornish  and  the  Wedgwood  crucibles,  are  all  burned  before 
use.  » 

It  may  be  further  observed,  that  the  pots  for  brass  are  too  porous 
for  gold  and  silver,  as  they  suck  up  too  much  of  the  same :  the 
black-lead  pots  are  closer  and  better  for  the  precious  metals,  and 
they  withstand  change  of  temperature  best  of  any  kind ;  they  are 
however  the  most  expensive,  but  cannot  be  safely  used  with  fluxes. 
The  Hessian  crucibles  resist  the  fluxes,  and  serve  with  care  for 
several  consecutive  meltings ;  the  English  clay  pots,  which  resem- 
ble the  Hessian,  are  safe  for  one  or  sometimes  for  more  meltings, 
and  their  cost  is  trifling.  The  pots  for  gold  and  silver  are  occasion- 
ally coated  or  luted  externally  with  clay  as  a  protection. 

The  generality  of  the  metals  are  far  more  disposed  to  oxidation 
when  in  the  melted  condition  than  when  solid;  it  is  therefore  usual, 
whilst  they  are  in  the  crucible,  to  protect  their  surfaces  from  the 
air  with  some  flux,  to  lessen  their  disposition  to  oxidize. 

In  the  iron  furnace,  the  slag  from  the  lime  floats  on  the  metal 
and  fulfils  this  end ;  many  brass-founders  always  throw  broken 
glass,  charcoal  dust,  sandiver,  or  sal-en ixon,  into  the  melting  pot; 
by  others  these  precautionary  measures  are  altogether  neglected. 
The  black  and  white  fluxes,  borax,  and  saltpetre  are  also  used  for 
the  precious  metals,  and  oil  or  resin  for  the  more  fusible,  as  lead  or 
tin ;  but  excess  of  heat  should  be  at  all  times  avoided. 


224:  THE  PEACTICAL   METAL-WORKER'S   ASSISTANT. 

The  generality  of  the  fusible  metals  may  be  mixed  in  all  pro- 
portions. Those  in  which  the  melting  points  are  tolerably  similar 
may  be  easily  combined,  such  as  lead  with  tin,  or  gold  with  silver 
or  copper  ;  these  appear  to  call  for  no  instructions  beyond  modera- 
tion in  the  heat  employed,  but  the  difficulty  of  making  definite  and 
uniform  alloys  increases  when  the  melting  point  of  the  metals,  or 
their  qualities  or  quantities,  are  widely  dissimilar. 

In  mixing  alloys  with  new  metals,  it  is  usual  to  melt  the  less 
fusible  first,  and  subsequently  to  add  the  more  fusible ;  the  mix- 
ture is  then  stirred  well  together,  and  common  opinion  seems  to  be 
in  favor  of  running  the  metal  into  an  ingot  mould,  as  the  second 
fusion  is  considered  more  thoroughly  to  incorporate  the  mixture. 
Sometimes,  with  the  same  view,  the  alloy  is  granulated,  by  pouring 
it  from  the  crucible  into  water,  either  from  a  considerable  height 
through  a  colander,  or  over  a  bundle  of  birch  twigs,  which  subdi- 
vide it  into  small  pieces;  others  condemn  such  practices,  and 
greatly  prefer  the  first  fusion,  in  order  to  avoid  oxidation,  and  de- 
parture from  the  intended  proportions. 

But  in  many,  and  perhaps  in  most  cases,  it  is  the  practice  to  fill 
the  melting  pan,  or  the  crucible,  in  part  with  old  alloy,  consisting 
of  fragments  of  spoiled  or  worn-out  work ;  and  to  which  is  added, 
partly  by  calculation  but  principally  by  trial,  a  certain  quantity  of 
new  metals.  This  is  not  always  done  from  motives  of  economy 
alone,  but  from  the  opinion  that  such  mixtures  cast  and  work  better 
than  those  made  entirely  of  new  metals. 

When  small  quantities  of  metal  of  difficult  fusion,  are  added  to 
large  proportions  of  others  which  are  much  more  fusible,  the  whole 
quantities  are  not  mixed  at  once.  Thus  in  pewter,  it  would  be 
scarcely  possible  to  throw  into  the  melted  tin  the  half  per  cent,  or 
the  one  per  cent,  of  melted  copper  with  any  certainty  of  the  two 
combining  properly,  and  it  is  therefore  usual  to  melt  the  copper  in 
a  crucible,  and  to  add  to  it  two  or  three  times  its  weight  of  melted 
tin;  this,  as  it  were,  dilutes  the  copper,  and  makes  the  alloys 
known  as  temper,  which  may  be  fused  in  a  ladle,  and  added  in  small 
quantities  to  the  fluid  pewter  or  to  the  tin,  as  the  case  may  be, 
until  on  trying  the  mixture  by  the  assay  its  proportions  are  con- 
sidered  suitable. 

The  metal  for  printers'  type  is  often  mixed  nearly  in  the  same 
manner ;  the  copper  is  first  melted  alone  in  a  crucible,  the  anti- 
mony is  melted  in  another  crucible,  and  is  poured  into  the  copper  ; 
sometimes  a  little  lead  is  also  added.  The  hard  alloy  and  the  tin 
are  then  introduced  to  the  mass  of  type-metal  or  lead,  also  in  great 
measure  by  trial,  as  old  metal  mostly  enters  into  the  mixture. 

The  composition  of  Britannia  metal  is  as  follows :  3|  cwt.  of 
best  block  tin  ;  28  Ibs.  of  martial  regulus  of  antimony ;  8  Ibs.  of 
copper,  and  8  Ibs.  of  brass.  The  amalgamation  of  these  metals  is 
effected  by  melting  the  tin,  and  raising  it  just  to  a  red  heat  in  a 
stout  cast-iron  pot  or  trough,  and  then  pouring  into  it,  first  the 
regulus,  and  afterwards  the  copper  and  brass,  from  the  crucibles 


MELTING   AND   MIXING  THE   METALS.  225 

in  which  they  have  been  respectively  melted,  the  caster  meanwhile 
stirring  the  mass  about  during  this  operation,  in  order  that  the 
mixture  may  be  complete. 

It  would  appear,  however,  much  more  likely  and  consistent  that 
a  similar  mode  is  adopted  in  making  this  alloy,  as  in  pewter  and 
type-metal ;  namely,  that  the  copper  and  brass  are  melted  together 
in  one  crucible,  the  antimony  then  added  from  another  crucible, 
anfl  perhaps  also  a  little  tin;  this  would  dilute  the  hard  metals,  and 
make  a  fusible  compound,  to  be  added  to  the  remainder  of  the  tin 
when  raised  a  very  little  beyond  its  fusing  point,  so  as  to  maintain 
fluidity  when  the  whole  were  mixed  and  stirred  together,  pre- 
viously to  being  poured  into  ingots.  By  this  treatment  the  tin 
would  be  much  less  exposed  to  waste. 

When  a  very  oxidizable  or  volatile  metal,  as  zinc,  is  mixed  with 
another  metal  the  fusing  point  of  which  is  greatly  higher,  as  with 
copper  for  making  the  important  alloy  brass,  whatever  weight  of 
each  may  be  put  into  the  crucible,  it  is  scarcely  possible  to  speak 
with  any  thing  like  certainty  of  the  proportions  of  the  alloy  pro- 
duced, from  the  rapid  and  nearly  uncontrollable  manner  in  which 
the  waste  of  the  zinc  occurs. 

Various  means  have  been  devised  at  different  times  for  combin- 
ing these  two  metals. 

Although  the  most  direct  way  of  forming  the  different  kinds  of 
brass  is  by  immediately  combining  the  metals  together,  one  of 
them,  which  is  most  properly  called  brass,  was  manufactured  long 
before  zinc,  one  of  its  component  parts,  was  known  in  its  metallic 
form.  The  ore  of  the  latter  metal  was  cemented  with  sheets  of 
copper,  charcoal  being  present.  The  zinc  was  formed  and  united 
with  the  copper,  without  becoming  visible  in  a  distinct  form.  The 
same  method  is  still  practised  for  making  brass. 

The  best  way  of  uniting  zinc  with  copper,  in  the  first  instance, 
will  be  to  introduce  the  copper  in  thin  slips  into  the  melted  zinc, 
till  the  alloy  requires  a  tolerable  heat  to  fuse  it,  and  then  to  unite 
it  with  the  melted  copper. 

Some  persons  thrust  the  whale  of  the  copper,  in  thin  plates,  into 
the  melted  zinc,  which  rapidly  dissolves  them  ;  and  the  mass  is 
kept  in  a  pasty  condition  until  within  a  few  minutes  of  the  time 
of  pouring,  when  they  augment  the  heat  to  the  degree  required 
for  the  casting  process. 

But  the  plan  which  is  the  most  expeditious,  and  now  most  usu- 
ally adopted,  is  to  thrust  the  broken  lumps  of  zinc  beneath  the 
surface  of  the  melted  copper  with  the  tongs,  which  mode  will  be 
more  particularly  described  ;  but  howsoever  conducted,  a  consid- 
erable waste  of  the  zinc  will  inevitably  occur. 

It  is  also  certain  that  every  successive  fusion  wastes,  in  so;;; •• 
degree,  the  more  oxidizable  metal,  so  that  the  original  proportion 
is  more  and  more  departed  from,  especially  with  the  least  excess  of 
heat ;  and  when  the  metals  are  not  well  covered  with  flux.  The 
loose  oxide  frequently  mixes  with  the  metal ;  this  in  brass  gives 
lo 


226  THE   PRACTICAL   METAL-WOEKEB'S   ASSISTANT. 

rise  to  the  white-colored  stains,  and  the  little  cavities  filled  with  the 
white  oxide  of  zinc  ;  and  in  gun-metal  the  stains  and  streaks  are 
blacker,  and  the  oxide  of  tin  (or  putty  powder)  being  much 
harder  than  the  former,  is  sadly  destructive  to  the  tools.  The 
vitreous  fluxes  collect  these  oxides,  and  are  therefore  serviceable  ; 
but  when  in  excess,  they  are  liable  to  run  into  the  mould  when  the 
metal  is  poured.  The  chemist  generally  uses  covers  to  the  cruci- 
bles, to  lessen  the  access  of  air,  and  therefore  the  oxidation ;  but 
th*e  brass-founder  frequently  leaves  the  metal  entirely  uncovered. 
No  considerable  waste  occurs  until  the  metal  is  entirely  fused  and 
rather  hotter  than  is  required  for  pouring,  which  is  indicated  lay 
the  zinc  beginning  to  burn  at  the  surface  with  a  blue  flame. 

The  loss  which  occurs  in  melting  brass-filings  is  a  proof  that 
the  granulation  of  the  metals  is  not  always  desirable  ;  and  unless 
the  brass-filings  are  well  drawn,  by  a  group  of  magnets,  to  free 
them  from  particles  of  iron  and  steel,  the  latter  often  spoil  the  cast- 
ings, as  they  become  so  exceedingly  hard  as  to  resist  the  file  or 
turning-tool,  and  can  be  only  removed  by  the  hammer  and  cold- 
chisel. 

In  collecting  the  several  alloys  given  at  pages  180  to  203,  espec- 
ially those  of  copper,  I  found  great  difficulty  in  reconciling  many 
of  the  statements  derived  from  books ;  and  therefore,  to  place  the 
m'atter  upon  a  surer  basis,  and  also  with  some  other  views,  I  de 
termined  to  mix  a  series  of  the  copper  alloys,  in  quantities  of  from 
one  to  two  pounds  each,  pursuing,  as  nearly  as  possible,  the  com- 
mon course  of  foundry  work,  to  make  .the  results  practical  and 

n    i 

useful. 

My  first  intention  was  to  weigh  the  metals  into  the  crucible,  and 
to  find,  by  the  weight  of  the  product,  the  amount  of  loss  in  every 
case,  as  well  as  the  quality  of  the  alloy.  Commencing  with  this 
view,  with  copper  and  zinc,  the  several  attempts  entirely  failed, 
owing  to  the  extremely  volatile  nature  of  the  latter  metal,  espec- 
ially when  exposed  to  the  high  temperature  of  melted  copper. 
The  difficulty  was  greatly  increased  owing  to  the  very  large  extent 
of  surface  exposed  to  the  air  compared  with  that  which  occurs 
when  greater  quantities  are  dealt  with,  and  the  increased  rapidity 
with  which  the  whole  was  cooled. 

The  zinc  was  added  to  the  melted  copper  in  various  ways, 
namely, — in  solid  lumps,  in  thin  sheets  hammered  into  balls, 
poured  in  when  melted  in  an  iron  ladle :  and  all  these,  both  whilst 
the  crucible  was  in  the  fire  and  after  its  removal  from  the  same. 
The  surface  of  the  copper  was  in  some  cases  covered  with  glass  or 
charcoal,  and  in  others  uncovered,  but  all  to  no  purpose,  as  from 
one-eighth  to  one-half  the  zinc  was  consumed  with  most  vexatious 
brilliancy,  according  to  the  modes  of  treatment :  and  these  methods 
were  therefore  abandoned  as  hopeless. 

I  was  the  more  diverted  from  the  above  attempts  by  the  well- 
known  fact  that  the  greatest  loss  always  occurs  in  the  first  mixing 
of  the  two  metals,  and  which  the  founder  is  in  general  anxious  to 


MELTING   AND   MIXING   THE    METALS.  227 

avoid.  Thus,  when  a  very  small  quantity  of  zinc  is  required,  as 
for  the  so-called  copper  casting,  about  4  oz.  of  brass  are  added  to 
every  2  or  3  Ibs.  of  copper.  And  in  ordinary  work,  a  pot  of  brass 
weighing  40  Ibs.  is  made  up  of  10,  20,  or  30  Ibs.  of  old  brass,  and 
two-thirds  of  the  remainder  of  copper.  These  are  first  melted.  A 
short  time  before  pouring,  the  one-third  of  the  new  metals,  or  the 
zinc,  is  plunged  in  when  the  temperature  of  the  mass  is  such  that 
it  just  avoids  sticking  to  the  iron  rod  with  which  it  is  stirred. 

In  mixing  the  copper  and  zinc  for  my  experiments  on  brass,  an 
entirely  different  course  was  therefore  determined  upon,  namely, 
to  melt  the  metals  on  a  large  scale,  and  in  the  usual  proportion — 
that  is,  24  Ibs.  of  copper  to  12  Ibs.  of  zinc — to  learn  the  first  loss 
of  zinc  when  conducted  with  ordinary  care.  Then  to  remelt  a 
quantity  of  the  alloy  over  and  over  again,  taking  a  trial-bar  every 
time  in  order  to  ascertain  the  average  loss  of  zinc  in  every  fusion. 
From  the  residue  of'  the  original  mixture,  to  make  the  alloys  con- 
taining less  zinc,  by  a  proportional  addition  of  copper ;  and  those 
alloys  containing  more  zinc,  by  a  similar  addition  of  zinc.  And 
lastly,  to  have  the  whole  of  the  bars  assayed,  to  determine  the  ab- 
solute proportion  of  copper  and  zinc  contained  in  all,  and  from 
these  analyses  to  select  my  series  of  specimens,  as  nearly  in  agree- 
ment as  I  could  with  the  proportions  in  common  use.  This  method 
answered  every  expectation. 

Twenty- four  pounds  of  copper,  namely,  clean  ship's  bolts,  were 
first  melted  alone  to  ascertain  the  loss  sustained  by  passing  through 
the  fire,  which  was  found  to  be  barely  ^  oz.  on  the  whole.  A  simi- 
lar weight  of  the  same  copper  was  weighed  out,  and  also  12  Ibs. 
of  the  best  Hamburg  zinc,  in  cakes  about  f  inch  thick,  which 
were  broken  into  pieces. 

The  copper  was  first  melted,  and  when  the  whole  was  nearly 
run  down  the  coke  was  .removed  to  expose  the  top  of  the  pot, 
which  was  watched  until  the  boiling  of  the  copper,  arising  probably 
from  escape  of  bubbles  of  air  locked  up  at  the  lower  part  of.  the 
semi-fluid  mass,  ceased,  and  the  copper  assumed  a  bright  red  but 
sluggish  appearance.  The  zinc  was  then  added. 

Precaution  is  necessary  in  introducing  the  first  quantity  of  zinc 
not  to  set  the  copper,  which  is  liable  to  occur  if  a  large  quantity 
of  cold  metal  is  thrown  in,  simply  from  the  abstraction  of  heat ; 
and  it  is  also  necessary  to  warm  the  zinc,  that  it  may  be  perfectly 
dry,  as  the  least  moisture  would  drive  the  metal  out  of  the  pot 
with  dangerous  violence.  A  small  lump  of  zinc,  therefore,  was 
taken  in  the  tongs,  held  beside  the  pot  for  a  few  moments,  and  then 
put  in  with  the  tongs  with  an  action  between  a  stir  and  a  plunge, 
regardless  of  the  flare,  and  of  the  low  crackling  noise,  just  as  if 
butter  had  been  thrown  in.  The  zinc  was  absorbed,  and  the  sur- 
face of  the  pot  was  clear  from  its  fumes  almost  immediately.  The 
remainder  of  the  zinc  was  then  directly  added,  in  about  eight 
pieces,  one  at  a  time,  much  in  the  same  manner,  but  the  danger  of 
setting  the  copper  nearly  ceases  when  a  small  quantity  of  the 


228  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

spelter  is  introduced.  After  every  addition  the  pot  was  free  from 
flame  in  a  few  moments.  A  handful  of  broken  glass  was  then 
thrown  in,  the  tile  replaced,  and  the  whole  allowed  to  stand  for 
about  fifteen  minutes  to  raise  the  metal  to  the  proper  heat  for 
pouring,  which  is  denoted  by  the  commencement  of  the  blue  fumes 
of  the  zinc. 

The  pot  was  then4aken  from  the  fire,  well  stirred  for  one  minute, 
and  poured ;  the  weight  of  the  brass  yielded  was  34  Ibs.  12  J  oz., 
showing  a  loss  of  1  Ib.  3|  oz.,  or  one-tenth  of  the  zinc,  or  the  one- 
thirtieth  part  of  the  whole  quantity.  This  experiment  was  re- 
peated, and  the  loss  was  then  1  Ib.  3  oz.,  the  difference  being  only 
£  an  oz.  By  analysis,  the  mean  of  the  two  brasses  was  31£  per 
cent,  zinc ;  or  instead  of  being  8  oz.  to  the  pound,  it  was  only  7  J  oz. 

Twelve  pounds  of  each  of  these  experimental  mixtures  were  re- 
melted  six  times,  a  bar  weighing  about  one  pound  and  a  half -being 
taken  every  time ;  the  two  series  of  trials  were  conducted  in  differ- 
ent foundries,  by  different  men,  and  quite  in  the  ordinary  course  of 
work ;  but  the  loss  per  cent,  of  zinc  was  in  the  six  experiments  ex- 
actly alike  in  each  series,  that  is,  each  bar,  after  the  sixth  melting, 
contained  22J  per  cent,  or  4§  oz.  to  the  pound  of  copper.  The 
second  fusion  in  each  case  sustained  the  greatest  loss,  (say  nearly 
two-fold ;)  and  in  the  others,  taking  all  the  accidental  circumstances 
into  account,  the  loss  might  be  pronounced  nearly  alike  every 
fusion 

In  making  the  alloys  with  more  zinc ;  the  calculated  weight  of 
the  first  alloy  was  melted,  and  the  amount  of  zinc  was  warmed  and 
plunged  in  with  the  tongs,  whilst  the  pot  was  in  the  fire,  the  whole 
was  stirred  and  quickly  poured :  the  losses  in  weight  were  rather 
large,  but  this  is  common  when  the  zinc  is  in  great  quantity.  To 
make  the  alloys  containing  less  zinc  than  the  alloy,  the  calculated 
weight  of  copper  was  first  made  red-hot  and  the  respective  portion 
of  the  brass  alloy  was  then  put  in  the  pot,  by  which  means  the  two 
ran  down  nearly  together :  it  being  found  that  the  copper,  if  en- 
tirely melted  before  the  brass  was  added,  incurred  a  risk  of  being 
set  at  the  bottom  of  the  pot ;  and  remelting  the  mass,  wasted  the 
zinc.  These  alloys  came  out  much  nearer  to  their  intended 
weights. 

In  making  the  tin  and  copper  alloys,  very  little  difficulty  was 
experienced.  The  copper  was  put  into  the  pot  together  with  a 
little  charcoal,  which  was  added  to  assist  the  fusion  and  also  to 
cause  the  alloy  to  run  clean  out ;  as  in  pouring  gun- metal  a  small 
quantity  is  usually  left  on  the  lip  of  the  crucible,  which  would  have 
been  an  interference  in  these  experiments.  When  the  copper  had 
ceased  boiling,  and  was  at  a  bright  red  heat,  it  was  taken  from  the 
fire,  and  the  tin  previously  melted  in  a  ladle,  was  thrown  in ;  every 
mixture  was  well  stirred  and  poured  immediately. 

In  the  fourteen  alloys  thus  formed,  each  weighing  about  a  pound 
and  a  half,  namely,  |,  1,  1|,  etc.,  up  to  8  oz.  of  tin  to  the  pound  of 
copper,  (missing  the  6|  and  7£,)  no  material  loss  was  sustained  in 


MELTING  AND   MIXING  THE   METALS.  22& 

nine  instances,  and  in  the  other  five  it  never  exceeded  £  oz.,  and 
that  quantity  was  probably  lost  rather  in  fragments  than  by 
oxidation. 

Alloys  of  2,  4,  6  and  8  ounces  of  lead  to  the  pound  of  copper, 
were  made  exactly  under  the  same  circumstances  as  the  last. 

Messrs.  Barron  and  Brother,  of  New  York,  manufacture  a  very 
effective  and  economical  furnace,  which  supplies  the  necessary 
qtiantity  of  air ;  for  in  the  combustion  of  fuel  only  a  certain  quantity 
of  air  is  required,  either  an  excess  or  deficiency  is  prejudicial  to 
proper  combustion.  , 

The  metals  are  melted  by  this  furnace  in  less  time,  and  at  a  less 
expense  of  fuel  than  any  that  have  fallen  under  my  notice. 

In  less  than  ten  minutes,  gold,  silver,  and  copper  can  be  melted 
by  the  furnace  of  Barron  and  Brother.  The  first  size  will  melt 
from  4  to  12  ounces  of  gold  with  about  a  quart  of  coal ;  the  second 
size  will  melt  50  to  120  ounces  with  about  two  quarts ;  and  the 
third  size  will  melt  from  100  to  500  ounces  with  three  or  four 
quarts  of  coal. 

It  is  a  difficulty  of  no  ordinary  descripton  to  ascertain  the  tem- 
perature of  a  furnace  with  sufficient  accuracy.  Every  fire  and 
every  furnace  is  continually  changing  its  temperature.  When  a 
furnace  is  charged  with  a  fresh  supply  of  fuel,  its  temperature  is 
lowered  by  the  absorption  of  heat  which  the  cold  fuel  takes  up 
when  thrown  upon  the  fire. 

The  temperature  is  lowered  by  a  rush  of  cold  air  through  the 
open  door.  Experiments  made  by  the  pyrometer  showing  the 
mean  temperature  of  the  flues  in  a  steam-engine  boiler,  and  the 
effects  produced  by  the  admission  of  air  through  a  permanent  and 
regulated  apparatus  behind  the  bridge,  indicate  that  in  making  the 
quantity  of  water  evaporated  by  one  pound  of  coal  as  the  measure 
of  economy,  the  mean  of  nearly  the  whole  experiments  is  about 
12  £  per  cent,  in  favor  of  a  regulated  and  continuous  supply  of  air. 
In  order  to  insure  economy  and  effect  in  the  combustion  of  fuel,  a 
large  supply  of  air  must  be  admitted  to  the  furnace,  and  that  in  the 
ratio  of  10  volumes  of  air  to  1  of  coal  gas.  Perfect  combustion  is 
the  prevention  of  smoke.  And  it  is  found  that  in  order  to  render 
the  residue  of  the  products  of  combustion  transparent  or  smokeless, 
a  supply  of  air  amounting  to  ten  times  the  gases  evolved  must  be 
admitted. 


230  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

CHAPTER  XY. 

9 

CASTING  AND  FOUNDING. 

METALLIC  MOULDS. — We  are  indebted  to  the  fusibility  of  the 
metals,  for  the  power  of  giving  them  with  great  facility  and  per- 
fection, any  required  form,  by  pouring  them  whilst  in  the  fluid  state 
into  moulds  of  various  kinds,  of  which  the  castings  become  in 
general  the  exact  counterparts.  This  property  is  of  immeasurable 
value. 

Some  few  objects  are  cast  in  open  moulds,  so  that  the  upper  sur- 
face of  the  fluid  metal  assumes  the  horizontal  position  the  same  as 
other  liquids,  as  in  casting  ingots,  flat  plates,  and  some  few  other 
objects ;  but  in  general  the  metals  are  cast  in  close  moulds,  so  that 
it  becomes  necessary  to  provide  one  or  more  apertures  or  ingates 
for  pouring  in  the  metal,  and  for  allowing  the  escape  of  the  air 
which  previously  filled  tlie  moulds. 

"When  these  moulds  are  made  of  metal,  they  must  be  sufficiently 
hot  not  to  chill  or  solidify  the  fluid  metal  before  it  has  time  to 
adapt  itself  thoroughly  to  every  part  of  the  mould  :  and  when  the 
moulds  are  made  of  earthy  matters,  although  moisture  is  essential 
to  their  formation,  little  or  none  should  remain  at  the  time  they 
are  filled. 

The  earthen  moulds  must  be  also  sufficiently  pervious  to  air, 
that  any  vapor  or  gases  which  may  be  formed,  either  at  the  mo- 
ment of  pouring  in  the  metal  or  during  its  solidification,  may  have 
free  vent  to  escape ;  otherwise,  if  these  gases  are  rapidly  formed, 
there  is  great  danger  of  the  metal  being  driven  out  of  the  mould 
with  a  violent  explosion,  or  when  more  slowly  formed  and  locked 
up  without  sufficient  freedom  for  escape,  the  casting  will  be  said 
to  be  blown,  as  some  of  the  bubbles  of  air  will  displace  the  fluid 
metal  and  render  it  spongy  or  porous.  It  not  unfrequently  hap- 
pens that  castings  which  appear  externally  good  and  sound,  are 
full  of  hidden  defects,  because  the  surface  being  first  cooled,  the 
bubbles  of  air  will  attempt  to  break  their  way  through  the  central 
and  still  soft  parts  of  the  casting. 

The  explanatory  diagram,  Fig.  120,  is  intended  to  elucidate  some 
of  the  circumstances  concerning  the  construction  of  moulds,  which 
in  the  greater  number  of  cases  are  made  only  in  two  parts,  but  in 
other  cases  are  divided  into  several.  The  figure  to  be  moulded  is 
supposed  to  be  a  rod  of  elliptical  section,  the  mould  for  which 
might  be  divided  into  two  parts  through  the  line  A,  B,  because  no 
part  of  the  figure  projects  beyond  the  lines  a,  I,  drawn  from  the 
margin  of  the  model  at  right  angles  to  the  line  of  division,  and  in 
which  direction  the  half  of  the  mould  would  be  removed  or  lifted; 
the  model  could  be  afterwards  drawn  out  from  the  second  half  of 
the  mould  in  a  similar  manner. 


CASTING  AND   FOUNDING.  231 

The  mould  could  be  also  parted  upon  the  line  C,  D,  because  in 
that  direction  likewise,  no  part  of  the  model  extends  beyond  the 
lines  c,  d,  which  show  the  direction  in  which  the  mould  would  be 
then  lifted. 

Fig.  120. 

C  b 


The  mould,  however  complex,  could  be  also  parted  either  upon 
A  B  or  C  D,  provided  no  part  of  the  model  outstepped  the  rect- 
angle formed  by  the  dotted  lines  b,  c,  or  was  undercut. 

But  considering  the  figure  120  to  be  turned  bottom  upwards,  and 
with  the  line  E,  F,  horizontal,  the  removal  of  the  entire  half  of 
the  mould  upon  the  lines  e,f,  would  be  impossible,  because  in  rais- 
ing the  mould  perpendicularly  to  E,  F,  that  portion  of  the  mould 
situated  within  the  one  perpendicular  e,  would  catch  against  the 
overhanging  part  of  the  oval  towards  A.  Were  the  mould  of  metal, 
and  therefore  rigid,  it  would  be  entirely  locked  fast,  or  it  would 
not  "  deliver  ;"  were  the  mould  of  sand,  and  therefore  yielding,  it 
would  break  and  leave  behind  that  part  between  A  and  E  which 
caused  the  obstruction.  Consequently,  in  such  a  case,  the  mould 
would  be  made  with  a  small  loose  part  between  A  and  E,  so  that 
when  the  principal  portion,  from  A  to  F,  had  been  lifted  perpendic- 
ularly or  in  the  direction  of  the  line  e,  the  small  undercut  piece. 
A  to  E,  might  be  withdrawn  sideways,  on  which  account  it  would 
be  designated  by  the  iron  founder  a  drawback,  by  the  brass  founder 
a  false  core. 

All  the  patterns  in  the  mould,  Fig.  121,  could  be  extracted  from 
each  half  the  mould,  because  none  of  them  encroach  beyond  the 
perpendicular  line,  or  that  in  which  the  mould  is  lifted ;  a  and  b, 
could  be  laid  in  exactly  upon  the  diagonal,  or  upon  one  flat  side, 
or  partly  embedded ;  and  in  like  manner  f,  g,  h,  might  be  sunk 
more  or  less  into  tl;e  mould,  their  sides  bein^  perpendicular  ;  but 
the  patterns  in  Fig.  122  being  undercut,  the  division  of  the  mould 
into  two  parts  only  would  be  impracticable,  and  false  cores  or  sub- 
divisions would  be  required  in  the  manner  represented,  the  con- 
struction of  which  will  be  hereafter  detailed. 

Extending  these  same  views  to  a  more  complex  object,  such  as 
a  bust,  it  will  be  conceived  that  the  mould  must  be  divided  into 


232 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


so  many  pieces,  that  none  of  them  will  be  required  to  embrace 
any  overhanging  part  of  the  figure.    For  instance,  were  it  attempted 


to  mould  a  human  head,  so  that  the  parting  might  pass  through 
the  central  line  of  the  face  and  down  the  back,  the  two  halves 
could  not  be  separated  if  they  were  made  each  in  a  single  piece ; 
as  the  inner  angles  of  the  eyes,  the  spaces  behind  the  ears,  and  the 
(juris  of  the  hair  would  obstruct  it,  and  the  head  could  be  only 
thus  moulded  by  making  false  cores  or  loose  pieces  at  these  par- 
ticular places,  in  the  manner  illustrated  by  the  former  figures. 
These  would  require  to  be  accurately  adapted  to  the  surrounding 
parts,  by  pins  and  contrivances  to  ensure  their  re-taking  their 
true  positions.  These  remarks,  however,  are  only  advanced  by 
way  of  general  illustration,  as  figure  casting  is  the  most  refined 
part  of  the  art  of  moulding. 

Metal  moulds  are  employed  for  many  works  in  the  easily -fused 
metals,  which  are  required  to  be  produced  in  large  quantities,  and 
with  great  similitude  and  economy:  the  examination  of  which 
moulds  will  serve  to  demonstrate  many  of  the  points  of  construc- 
tion and  proceeding.  Thus  the  common  bullet  mould  is  made 
like  a  pair  of  pliers,  the  jaws  of  which  are  conjointly  pierced  with 
a  hole  or  passage  leading  into  a  spherical  cavity ;  the  aperture  is 
equally  divided  between  the  two  halves  of  the  mould,  so  that  in 
fact  the  division  is  truly  upon  the  diametrical  line  both  of  the 
sphere  and  the  runner,  or  the  largest  part  of  each,  otherwise  the 
pliers  could  not  be  opened  to  remove  the  bullet  when  cast.  Iron 
shot  for  great  guns  are  likewise  cast  in  iron  moulds,  by  which 
they  also  possess  great  accuracy  of  form  and  size. 


Figs.  123 


124. 


CASTING   AND    FOUNDING.  233 

Figs.  123  to  126  represent  the  moulds  for  casting  pewter  ink- 
stands :  these  moulds  are  a  little  more  complex,  and  are  each  made 
in  four  parts ;  the  black  portions  represent  the  sections  of  the  ink- 
stands to  be  cast.  The  moulds  each  consist  of  a  top  piece  or  cap  t, 
a  bottom  or  core  b,  and  two  sides^or  cottks,  s  s  ;  in  Fig.  126,  the  one 

Figs.  125  126. 


side  is  removed,  in  order  to  expose  the  casting,  and  the  top  piece  t 
is  supposed  to  be  sawn  through  to  make  the  whole  more  distinct. 
It  will  be  seen,  the  top  and  bottom  parts  have  each  a  rebate  like 
the  lid  of  a  snuff-box,  which  embraces  the  external  edges  of  the 
two  side  pieces  s  s,  and  the  latter  divide  as  in  the  bullet  mould, 
exactly  upon  the  diametrical  line  of  the  inkstand,  which  in  a  cir- 
cular object  is  of  course  the  largest  part ;  the  positions  of  the  parts 
are  therefore  strictly  maintained. 

When  the  mould  has  been  put  together,  laid  upon  its  side,  and 
filled  through  x,  the  ingate,  or  as  it  is  technically  called,  the  tedge, 
it  is  allowed  to  stand  about  a  minute  or  two,  and  then  the  top  t,  is 
knocked  off  by  one  or  two  light  blows  of  a  pewter  mallet ;  the 
mould  is  then  held  in  the  hand  and  the  bottom  part  or  core  is 
knocked  out  of  the  casting  by  the  edge ;  lastly,  the  two  sides  are 
pulled  asunder  by  their  handles,  and  the  casting  is  removed  from 
the  one  in  which  it  happens  to  stick  fast ;  but  it  requires  cautious 
handling  not  to  break  it.  The  face  of  the  mould  is  slightly  coated 
with  red  ochre  and  white  of  egg,  to  prevent  the  casting  adhering 
to  the  same,  and  to  give  the  works  a  better  face ;  the  first  few 
castings  are  generally  spoiled,  until  in  fact  the  mould  becomes 
properly  warmed. 

Most  of  the  works  made  in  the  very  useful  material,  pewter, 
are  cast  in  gun-metal  moulds,  which  require  much  skill  in  their 
construction ;  thus  a  pewter  tankard,  with  a  hinged  cover  and 
spout,  consists  of  six  pieces,  every  one  of  which  requires  a  dif- 
ferent mould;  thus, 

1.  The  body  has  a  mould  in  four  parts,  like  that  for  the  inkstand, 
but  it  is  filled  in  the  erect  position  through  two  ingates,  which  are 
made  through  the  top  piece  t,  of  the  mould : 

2.  The  bottom  requires  a  mould  in  two  parts,  and  is  poured  at 
the  edge : 

3.  The  cover  is  cast  in  the  same  manner;  and  thus  far  the 


234 


THE   PRACTICAL   METAL -WORKER'S   ASSISTANT. 


Figs.  127 


moulds  are  all  made  in  the  lathe,  in  which  useful  machine  these 
12g.         castings  are  also  finished  be- 
fore being  soldered  together : 

4.  The    spout    requires    a 
mould  in  two  parts : 

5.  The  piece,  Fig.  128,  by 
which  the  cover  is  hinged  to 
the   handle,  requires  a  much 
more  complex  mould,  which 
divides  in  four  parts,  as  shown 
in  Fig.  127,  and  much  resem- 
bles, except  in  external  form,  the  remaining  mould:  namely, 

6.  For  the  handle,  which  mould,  like  the  last  consists  of  four 
pieces  fitted  together  with  various  ears  and  projections ;  they  are 
represented  in  their  relative  positions  in  Fig.  130,  with  the  excep- 
tion of  the  piece  a,  Fig.  131,  which  is  detached  and  shown  bottom 
upwards.  Fig.  129  shows  the  pewter  handle  separately,  with  the 
three  knuckles  for  joining  on  the  cover :  and  on  reference  to  Fig. 
130,  of  the  five  parts  through  which  the  pin  p,  is  thrust,  the  two  ex- 
ternal pieces  belong  respectively  to  the  sides  c,  and  d,  of  the  mould, 
the  others  are  parts  of  the  casting,  and  the  two  hollows  are  formed 
by  the  two  solid  knuckles  fixed  to  the  detached  piece  of  the  mould 
a,  Fig.  131.  At  the  time  of  pouring,  the  pin  p,  serves  to  connect 
the  three  parts  a,  c,  d,  together,  and  also  to  form  the  whole  in  the 
casting,  for  the  pin  of  the  joint. 


Figs.  129 


130 


Fig.  132  shows  the  section  of  the  mould  upon  the  dotted  line  s: 
by  this  it  will  be  seen  the  handle  is  cast  hollow,  as  almost  imme- 
diately the  mould  has  been  filled  through  t,  all  but  the  thin  exter- 
nal shell  is  poured  out  again,  and  the  weight  is  reduced  to  less 
than  half.  To  extract  the  handle  the  pin  p  is  first  twisted  out ; 


CASTING  AND    FOUNDING. 


235 


then  the  joint  piece  a,  is  removed :  next  the  back  piece  b ;  and 
lastly  the  two  sides  c,  d,  are  pulled  asunder. 

Tin  or  pewter  bearings  for  locomotive  carriages,  have  been  cast 
in  appropriate  metal  moulds ;  and  such  materials  are  very  useful 
to  the  mechanist  for  many  temporary  purposes,  such  as  collars, 
bearings,  screws  and  nuts,  either  for  difficult  positions,  or  where  no 
screw  tap  is  at  hand  and  the  resistance  is  moderate ;  in  such  cases 
the  parts  of  the  machine  constitute  one  portion  of  the  mould,  the 
apertures  being  closed  with  moist  loam:  the  processes  are  most 
successful  when  the  parts  can  be  made  warm  and  the  clay  is  nearly 
dry. 

The  most  important,  exact,  and  interesting  example  of  casting 
in  metallic  moulds  is  that  of  type-founding,  the  description  of 
which,  as  well  as  drawings  of  the  mould,  have  been  repeatedly 
given ;  some  of  the  peculiarities  only  of  this  art,  will  be  therefore 
noticed.  Each  complete  set  of  types  consists  of  five  alphabets,  A, 
A,  a,  A,  a,  besides  many  other  characters,  in  all  about  two  hun- 
dred, and  which  are  required  to  be  most  strictly  aHke  in  every 
respect,  except  in  device  and  width ;  the  width  is  the  greatest  for 
the  W  and  M,  and  the  least  for  the  i  and  !.  Every  required  mea- 
sure of  the  types  (represented  on  an  enlarged  scale  in  Fig.  133),  is 
determined  by  the  mould  alone,  and  not  by  any  after  correction. 


If  the  moulds  for  the  rectangular  shafts  of  the  types  were  made 
as  in  Figs.  134  or  135,  the  usual  forms  of  square  moulds,  thev 
would  not  admit  of  alteration  in  width,  as  shifting  a,  Fig.  134, 
would  produce  no  change,  and  Fig.  135  would  thereby  produce 
the  form  b.  The  mould  which  is  used  is  made  in  two  L  formed 
parts,  as  in  Fig.  136,  whence  it  follows  that  shifting  the  part  a,  to 
the  right  or  left  increases  or  decreases  the  width  of  the  type  with- 


236  THE  PRACTICAL   METAL- WORKER'S   ASSISTANT. 

out  interfering  with  its  thickness,  or,  as  it  is  technically  called,  its 
body,  (B,  Fig.  133,)  the  width,  w,  is  adjusted  by  a  piece  called  the 
register,  fixed  at  the  bottom  of  the  mould. 

The  device  is  changed  by  placing  across  the  bottom  of  the  mould 
one  of  the  two  hundred  little  pieces  of  copper,  Fig.  137,  called 
matrices,  into  which  the  face  of  the  latter  is  impressed  by  very 
beautifully  formed  punches  The  length  of  the  letter  is  deter- 
mined by  contraction  at  the  upper  part  of  the  mould,  as  shown  at 
c,  Fig.  138,  which  represents  the  type  as  it  leaves  the  mould ;  the 
metal  is  poured  with  a  jerk,  to  make  a  sharp  impression  of  the 
matrix :  the  mould,  which  is  held  in  the  left  hand,  and  the  ladle  in  the 
right,  being  jerked  simultaneously  upwards,  at  the  moment  of  fill- 
ing the  mould,  and  without  which  the  face  of  the  type  would  be 
rounded  and  quite  imperfect.  The  breaks  c,  or  the  runners  of  the 
types,  are  first  broken  off,  and  after  a  slight  correction  of  the  sides, 
the  hollows  or  channels  in  the  feet  are  planed  out  of  a  whole  col- 
umn of  them,  fixed  between  bars  of  wood,  without  touching  the 
square  shoulders  which  determine  the  lengths  of  the  types,  and 
are  left  as  originally  cast. 

In  some  types  with  a  large  face  and  much  detail,  such  as  the 
illustrations  given  on  the  last  page,  the  motion  of  the  hand  is 
barely  sufficient  to  give  the  momentum  required  to  throw  the  me- 
tal into  the  matrix,  and  produce  a  clean  sharp  impression.  A 
machine  is  then  used,  which  may  be  compared  to  a  small  forcing- 
pump,  by  which  the  mould  is  filled  with  the  fluid  metal ;  but  from 
the  greater  difficulty  of  allowing  the  air  to  escape,  such  types  are 
in  general  considerably  more  unsound  in  the  shaft  or  body ;  so 
that  an  equal  bulk  of  them  only  weigh  about  three-fourths  as 
much  as  types  cast  in  the  ordinary  way  by  hand,  and  which  for 
general  purposes  is  preferable  and  more  economical. 

Some  other  variations  are  resorted  to  in  type-founding ;  some- 
times the  mould  is  filled  at  twice,  at  other  times  the  faces  of  the 
types  are  dabbed,  (the  clichee  process  ;)  many  of  the  large  types  and 
ornaments  are  stereotyped,  and  either  soldered  to  metal  bodies,  or 
fixed  by  nails  to  those  of  wood.  The  music  type,  and  ornamental 
borders  and  dashes,  display  much  very  curious  power  of  combina- 
tion. 

The  clichee  process  is  rather  stamping  than  casting.  The  melted 
alloy  is  placed  in  a  paper  tray,  and  stirred  with  a  card  until  it  as- 
sumes the  pasty  condition.  The  metal  die,  or  mould,  is  then  "  dab- 
bed" upon  the  soft  metal,  as  in  sealing  a  letter,  but  with  a  little 
more  of  sluggish  force. 

By  the  type-founding  machine  invented  by  Mr.  Bruce,  of  K  Y.; 
and  employed  in  the  extensive  foundry  of  Collins  aud  M'Leester,  of 
Philadelphia,  3600  letters  may  be  cast  in  an  hour,  much  more 
sound  and  as  perfect  as  those  cast  by  hand. 

PLASTER  OF  PARIS  MOULDS  AND  SAND  MOULDS. — Other  exam- 
ples of  metallic  moulds  might  be  given,  but  there  are  far  more 
frequent  cases  in  which  one  single  casting  is  alone  required ;  or 


CASTING  AND   FOUNDING  237 

else  the  number  is  so  small,  or  the  pieces  themselves  are  so  large 
or  peculiar,  that  the  construction  of  metal  moulds  would  be  found 
almost  or  quite  impracticable,  even  without  reference  to  an  equally 
fatal  barrier,  the  expense. 

In  making  these  single  copies  in  the  metals  of  considerable  fusi- 
bility, plaster  of  Paris  is  sometimes  employed ;  thus,  after  the 
printer  has  arranged  the  loose  types  into  a  page,  and  the  requisite 
corrections  have  been  made,  a  stereotype,  or  solid  type,  is  taken  of 
the  whole  as  a  thin  sheet  of  metal,  which  serves  to  be  printed  from 
almost  as  well  as  the  original  letters :  and  its  small  cost  enables  the 
printer  to  retain  it  for  future  use,  after  the  types  themselves  have 
served  perhaps  for  a  hundred  similar  regenerations,  and  are  ulti- 
mately worn  out. 

The  stereotype  founder  takes  a  copy  of  the  entire  mass  of  type 
in  plaster  of  Paris ;  this  is  dried  in  an  oven,  and  placed  face  down- 
wards within  a  cast-iron  mould,  like  a  covered  box,  open  at  the 
four  top-corners.  The  mould  and  plaster-cast  are  heated  to  the 
fusing  temperature  of  the  type-metal,  and  gradually  lowered  into  a 
pan  or  bath  of  the  same  by  means  of  a  crane ;  the  hot  fluid  metal 
runs  in  at  the  corners  of  the  mould,  and  raises  the  inverted  plas- 
ter, which  latter  would  rise  entirely  to  the  surface  but  for  the 
restraint  of  the  cover  of  the  mould. 

Type-metal  is  about  eleven  times  as  heavy  as  water  ;  and  if  the 
mould  be  immersed  four  inches  below  the  surface,  it  is  subjected  to 
a  pressure  equal  to  that  of  a  column  of  water  forty-four  inches 
high,  or  above  two  pounds  upon  every  square  inch. 

The  necessity  of  this  arrangement  is  shown  when  a  few  ounces 
of  type-metal  are  poured  from  a  ladle  on  the  face  of  the  plaster ; 
the  metal  looks  like  a  dump,  almost  without  any  mark  of  the  let- 
ters, whereas  the  stereotype-cast  is  nearly  as  sharp  as  the  original 
type.  The  immersion  fulfils  the  same  end  as  the  jerk  of  the 
hand-caster,  or  of  the  pump  occasionally  employed :  and  the  long 
continuance  of  the  mould  in  the  fluid  metal  allows  ample  time  for 
the  air  to  escape  in  bubbles  to  the  surface ;  after  which  the  mould 
is  raised  and  cooled  in  a  vessel  of  water,  and  the  plaster  is  mostly 
destroyed  in  its  removal. 

Plaster  of  Paris,  although  it  may  be,  and  frequently  is  used  for 
the  fusible  metals,  such  as  lead,  tin,  and  pewter,  cannot  be  em- 
ployed alone  for  iron,  copper,  brass,  and  many  other  metals,  the 
intense  melting  heats  of  which  would  calcine  the  material,  and 
cause  it  to  crumble ;  even  the  soft  metals  should  not  be  very  hot, 
or  they  will  make  the  plaster  of  Paris  blister  off  in  flakes  or  dust. 
\Ye  must  therefore  seek  a  substitute  better  capable  of  enduring 
the  heat,  and  likewise  susceptible  of  receiving  definite  forms ;  for 
•*  hich  purpose  damp  sand,  with  a  small  natural  or  subsequent 
admixture  of  clay  or  loam,  is  found  to  be  perfectly  adapted. 

The  moulding-sand  cannot,  however,  be  used  without  external 
support,  and  which  is  given  by  shallow  iron  frames  without  tops  or 
bottoms,  called  flasks,  represented  in  Figs.  139  and  140.  The  bot 


238 


THE  PRACTICAL   METAL- WORKER'S  ASSISTANT. 


torn  part,  4,  5,  is  supposed  to  have  been  rammed  full  of  sand,  and 
to  stand  upon  a  flat  board,  6.  The  model  of  the  plain  flat  bar 
which  is  to  be  cast,  is  now  laid  on  the  surface  of  the  sand,  that  of 


Fig.  139. 


Fig.  140. 


the  round  bar  is  imbedded  half  way  in  the  same,  and  the  mould  is 
dusted  with  dry  parting  sand. 

The  top  part  of  the  flask  2,  3,  is  shown  still  empty,  and  in  the 
act  of  being  attached  to  4,  5  by  its  pins,  which  enter  corresponding 
holes  in  the  latter,  easily  but  without  shake :  2,  3  is  also  rammed 
full  of  sand,  and  covered  with  a  top  board,  1,  not  represented  to 
avoid  confusion.  The  mould  is  now  opened,  the  models  are  removed, 
and  channels  are  scooped  out  from  the  ends  of  the  cavities  left  by 
the  models,  to  the  hollows  or  pouring-holes  at  the  end  of  the  flask: 
the  parts  are  all  replaced  in  the  order  1  to  6,  represented  in  Fig. 
139,  and  the  whole  are  fixed  together  by  screw  clamps,  so  as  to 
assume  the  condition  of  Fig.  140. 

The  flask  is  now  placed  almost  perpendicularly  beside  the  pour- 
ing-trough, and  the  metal  is  poured  into  it  from  the  crucible,  as 
shown  in  Fig.  119,  p.  221;  but  the  flask,  if  small,  is  put  on  the  sur- 
face of  the  pouring  or  spill-trough,  and  propped  up  with  a  short 
bar. 

This  brief  sketch  of  the  entire  process  of  moulding  and  casting 
in  sand  moulds,  will  be  now  followed  by  some  remarks  in  greater 
detail :  first  on  the  patterns  of  the  objects  to  be  cast ;  secondly,  on  the 
conditions  required  in  the  sand;  and  thirdly,  the  process  of  mould- 
ing simple  and  solid  bodies.  The  section  then  following  will  be 
devoted  to  moulding  cored  works,  and  figures,  after  which  a  few 
lines  will  be  given  upon  the  subject  of  filling  the  moulds. 

PATTERNS,  MOULDS,  AND  MOULDING  SIMPLE  OBJECTS.— The 
perfection  of  castings  depends  much  on  the  skill  of  the  pattern- 
maker, who  .  should  thoroughly  understand  the  practice  of  the 
moulder,  or  he  is  liable  to  make  the  patterns  in  such  a  manner 
that  they  cannot  be  used,  or  at  any  rate  be  well  used. 


CASTING   AND    FOUNDING.  239 

Straight-grained  deal,  pine,  and  mahogany,  are  the  best  woods 
for  making  patterns,  as  they  stand  the  best ;  screws  should  be  used 
in  preference  to  nails,  as  alterations  are  then  more  easily  made  in 
the  models,  and  glue  joints,  such  as  dovetails,  tenons,  and  dowels, 
are  also  good  as  regards  the  after  use  of  the  saw  and  plane  for  cor- 
rections and  alterations. 

Foundry  patterns  should  be  always  made  a  little  taper  in  the  parts 
which  enter  most  deeply  into  the  sand,  in  order  to  assist  their  removal 
from  the  same,  when  their  purposes  will  not  be  materially  interfered 
with  by  such  tapering.  The  pattern-maker,  therefore,  works  most 
of  the  thickness,  and  the  sides  or  edges,  both  internal  and  external, 
a  little  out  of  parallel  or  square,  perhaps  as  much  as  about  one-six- 
teenth to  one-eighth  of  an  inch  in  the  foot,  sometimes  much  more. 

When  foundry  patterns  are  exactly  parallel,  the  friction  of  the 
sand  against  their  sides  is  so  great  when  they  penetrate  deeply, 
that  it  requires  considerable  force  to  extract  them ;  and  which  vio- 
lence tears  down  the  sand,  unless  the  patterns  are  much  knocked 
about  in  the  mould,  to  enlarge  the  space  around  them.  This  rough 
usage  frequently  injures  the  patterns,  and  causes  the  castings  to 
become  irregularly  larger  than  intended,  and  also  defective  in  point 
of  shape,  from  the  mischief  sustained  by  the  moulds;  all  which  evils 
are  lessened  when  the  patterns  are  made  consistently  taper  and 
very  smooth. 

It  must  be  distinctly  and  constantly  borne  in  mind,  that  although 
patterns  require  all  the  methods,  care,  and  skill,  of  good  joinery  or 
cabinet-making,  they  must  not,  like  such  works,  be  made  quite 
square  and  parallel,  for  the  reasons  stated.  Sharp,  internal  angles 
should  in  general  -be  also  avoided,  as  they  leave  a  sharp  edge  or 
arris  in  the  sand,  which  is  liable  to  be  broken  down  in  the  removal 
of  the  pattern ;  or  to  be  washed  down  on  the  entry  of  the  metal 
into  the  mould.  Either  the  angle  of  the  model  should  be  filled 
with  wood,  wax,  or  putty,  or  the  sharp  edges  of  the  sand  should 
be  chamfered  off  with  the  knife  or  trowel.  Sharp  internal  angles 
are  very  injudicious  in  respect  also  to  the  strength  of  castings,  as 
they  seem  to  denote  where  they  will  be  likely  to  break ;  and  more 
resemble  carpentry  than  good  metallic  construction. 

Before  the  patterns  reach  the  founder's  hands,  all  the  glue  that 
may  have  been  used  in  their  construction  should  be  carefully 
scraped  off,  or  it  will  adhere  to  and  pull  down  the  sand.  The  best 
way  is  to  paint  or  varnish  wooden  patterns,  so  as  to  prevent  them 
from  absorbing  moisture,  as  they  will  then  hang  to  the  sand  much 
less,  and  will  retain  their  forms  much  better.  Whether  painted  or 
not,  they  deliver  more  freely  from  the  mould  when  they  are  well 
brushed  with  black  lead,  like  a  stove. 

In  patterns  made  in  the  lathe,  exactly  the  same  conditions  are 
required;  the  parts  which  enter  deeply  into  the  sand' should  be 
neither  exactly  cylindrical  nor  plane  surfaces,  but  either  a  little 
coned,  or  rounding,  as  the  case  may  be ;  and  the  internal  angles 
should  not  bo  turned  exactly  to  •  their  ultimate  form,  but  rather 


240  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

filled  in,  or  rounded,  to  save  the  breaking  down  of  the  sharp  edges 
of  the  mould. 

Foundry  patterns  are  also  made  in  metal ;  these  are  very  excel- 
lent, as  they  are  permanent;  and  when  very  small  are  less  apt  to 
be  blown  away  by  the  bellows  used  for  removing  the  loose  sand 
and  dust  from  the  moulds.  To  preserve  iron  patterns  from  rust- 
ing, and  to  make  them  deliver  more  easily,  they  should  be  allowed 
to  get  slightly  rusty,  by  lying  one  night  on  the  damp  sand ;  next, 
they  should  be  warmed  sufficiently  to  melt  beeswax,  which  is 
then  rubbed  all  over  them,  and  in  great  part  removed,  and  then 
polished  with  a  hard  brush  when  cold.  Wax  is  also  used  by  the 
founder  for  stopping  up  any  little  holes  in  the  wooden  patterns; 
whitening  is  likewise  employed,  as  a  quicker  but  less  careful  expe- 
dient ;  and  very  rough  patterns  are  seared  with  a  hot  iron.  The 
good  workman,  however,  leaves  no  necessity  for  these  corrections, 
and  the  perfection  of  the  pattern  is  well  repaid  by  the  superior 
character  of  the  castings. 

Metal  patterns  frequently  require  to  have  holes  tapped  into  them 
for  receiving  screwed  wires,  by  way  of  handles  for  lifting  them  out 
of  the  sand;  and  in  like  manner,  large  wooden  patterns  should  have 
screwed  metal  plates  let  into  them,  for  the  same  purpose,  or  the 
founder  is  compelled  to  drive  pointed  wires  into  them,  to  serve  as 
handles,  which  is  an  injurious  practice. 

The  flasks  or  casting-boxes  for  containing  the  sand,  are  made  of 
various  sizes.  Each  side  is  about  2  to  3  inches  deep.  They  are 
poured  at  the  edge  when  placed  nearly  vertical ;  but  for  large  brass 
works  the  practice  of  the  iron-founder  is  generally  followed,  who 
mostly  pours  his  work  horizontally,  through  a  hole  in  the  top,  as 
will  be  explained.  The  pins  of  the  flask  should  fit  easily,  but  with- 
out shake,  or  the  two  halves  will  shift  about  and  cause  a  disagree- 
ment or  slip  in  the  casting.  The  tools  used  in  making  the  moulds 
are  few  and  simple,  namely,  a  sieve,  shovel,  rammer,  strike,  mallet, 
a  knife,  and  two  or  three  loosening  wires  and  little  trowels,  which 
it  is  unnecessary  to  describe. 

The  principal  materials  for  making  foundry  moulds  are  very  fine 
sand  and  loam.  They  are  found  mixed  in  various  proportions,  so 
that  the  respective  quantities  proper  for  different  uses  cannot  be 
well  defined;  but  it  is  always  judicious  to  employ  the  least 
quantity  of  loam  that  will  suffice.  These  materials  are  seldom 
used  in  their  new  or  recent  states  for  brass  castings,  although  more 
so  for  iron,  and  the  moulds  made  of  fresh  sand  are  always  dried, 
as  will  be  explained. 

The  ordinary  moulds  are  made  of  the  old  damp  sand,  and  they 
are  generally  poured  immediately,  or  whilst  they  are  green  ;  some- 
times they  are  more  or  less  dried  upon  the  face.  The  old  working 
fine  sand  is  considerably  less  adhesive  than  the  new,  and  of  a  dark- 
brown  color.  This  arises  from  the  brick-dust,  flour,  and  charcoal- 
dust  used  in  moulding  becoming  mixed  with  the  general  stock, 
which  therefore  requires  occasional  additions  of  new  sand  or  loam, 


CASTING  AND   FOUNDING.  241 

so  that  when  slightly  moist  and  pressed  firmly  in  the  hand  it  may 
form  a  moderately  hard  compact  lump. 

Red  brick-dust  is  generally  used  to  make  the  partings  of  the 
mould,  or  to  prevent  the  damp  sand  in  the  separate  parts  of  the 
flask  from  adhering  together. 

The  face  of  the  mould  which  receives  the  metal  is  generally 
dusted  with  meal-dust,  or  waste  flour ;  but  in  large  works,  pow- 
'dered  chalk,  and  also  wood  or  tan  ashes,  are  used,  from  being 
cheaper.  The  moulds  for  the  finest  brass  castings  are  faced  either 
with  charcoal,  loamstone,  rottenstone,  or  a  mixture  of  the  same. 
The  moulds  are  frequently  inverted  and  dried  over  a  dull  fire  of 
cork  shavings,  or  when  dried  they  are  smoked  over  pitch  or  black 
resin  lighted  in  an  iron  ladle. 

The  gold  and  silver  casters  frequently  use  a  lighted  link  for 
facing  their  sand-moulds,  and  some  of  the  type-founders'  metallic 
moulds  are  smoked  over  a  lamp.  All  these  modes  deposit  a  fine 
layer  of  soot  upon  the  moulds. 

The  cores,  or  loose  internal  parts  of  the  moulds  for  forming  holes 
and  recesses,  are  made  of  various  proportions  of  new  sand,  loam 
and  horse-dung,  as  will  be  explained  in  the  section  on  cored  works. 
They  all  require  to  be  thoroughly  dried,  and  those  containing 
horse-dung  must  be  well  burned  at  a  red  heat ;  this  consumes  the 
straw  and  makes  them  porous,  and  of  a  brick- red. 

In  making  the  various  moulds,  it  becomes  necessary  to  pursue 
a  medium  course  between  the  conditions  best  suited  to  the  forma- 
tion of  the  mould  and  those  best  suited  to  filling  them  with  the 
red-hot  metal  without  risk  of  failure  or  accident.  Thus,  within 
certain  limits,  the  more  loam  and  moisture  the  sand  contains,  and 
the  more  closely  it  is  rammed,  the  better  will  be  the  impression 
of  the  model ;  but  at  the  same  time  the  moist  and  impervious  con- 
dition of  the  mould  would  then  incur  the  greater  risk  of  accident, 
both  from  the  moisture  and  from  the  non-escape  of  the  air.  There- 
fore the  policy,  on  the  score-  of  safety,  is  to  use  the  sand  as  dry  as 
practicable,  so  as  to  avoid  the  delay  of  after-drying,  and  also  to 
keep  the  mould  porous. 

The  founder,  therefore,  compromises  the  matter  by  using  a  little 
facing  sand  containing  rather  more  loam,  for  the  face  of  the  green 
moulds  for  general  work ;  and  in  those  cases  where  much  loam  is 
used,  the  moulds  are  thoroughly  dried  by  heat,  which  is  not  gen- 
erally necessary  with  ordinary  sand  moulds. 

The  power  of  conducting  heat  is  considerably  less  in  red-hot 
iron  than  in  copper  and  brass,  and  therefore  the  moulds  for  the 
latter  require  to  be  in  a  drier  condition  than  those  which  may  be 
used  for  iron;  but  in  either  case  the  presence  of  superfluous 
moisture  is  always  attended  with  some  danger  to  the  individual  as 
well  as  to  the  work. 

The  above  is  the  reason  generally  assigned  for  the  fact  that  the 
iron-founders  may  and  do  use  their'moulds  with  safety  when  sen- 
sibly more  moist  than  is  admissible  for  brass  and  copper  castings. 
16 


242  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

It  is  confirmatory  of  the  fact  that  the  more  dense  the  mould, 
the  drier  it  must  be,  as  the  sand  used  by  iron-founders  is  also 
coarser  and  therefore  more  porous  than  that  employed  by  brass- 
founders. 

Another  point  has  also  to  be  considered:  as  castings  contract 
considerably  in  cooling,  in  moulding  large  and  slight  works  the 
face  of  the  mould  must  not  be  too  strongly  rammed,  nor  too  much 
dried,  or  its  strength  may  exceed  that  of  the  red-hot  metal  whilst 
in  the  act  of  shrinking.  The  result  would  be,  that  in  contracting, 
the  casting  would  be  rent  or  torn  asunder  from  the  restraint  of  the 
mould ;  whereas  it  should  have  the  preponderance,  of  strength,  so 
as  to  pull  down  the  face  of  the  sand  instead  of  being  itself  de- 
stroyed. But  the  exact  condition  both  of  the  mould  and  of  the 
melted  metal,  must  be  determined  by  the  nature  of  the  object  to  be 
cast, — matters  which  can  be  only  referred  to  with  the  development 
of  the  practice  of  the  foundry,  and  upon  which  we  shall  now 
commence. 

The  sand  having  been  prepared,  and  the  appropriate  flask  and 
boards  selected,  the  moulder  first  examines  every  pattern  sepa- 
rately to  determine  the  most  appropriate  way  of  inserting  it  in  the 
flask,  as  explained  by  Fig.  121,  p.  232 ;  also  to  see  that  patterns, 
such  as  /  and  h,  therein  shown,  are  smallest  at  the  parts  entering 
the  most  deeply  into  the  sand,  in  order  that  they  may  deliver  well. 
It  should  also  be  noticed  whether  they  are  perfectly  smooth,  and 
that  there  is  no  glue  hanging  about  them,  which  would  cause  them 
to  adhere  and  to  pull  down  the  moist  sand. 

The  bottom  flask,  4,  5,  p.  238,  is  placed  on  a  board  not  less  than 
an  inch  or  two  longer  and  wider  than  itself,  with  the  face  4,  down- 
wards, and  it  is  filled  from  the  side  5.  A  srrfall  portion  of  the 
strong  faeing-sand  is  rubbed  through  a  fine  sieve ;  the  remainder 
is  thrown  in  from  the  trough  with  the  shovel,  and  the  moulder 
drives  the  whole  moderately  hard  into  the  flask,  either  with  a 
mallet,  the  handle  of  the  spade,  or  other  rammer  ;  or  else  he  jumps 
up  by  aid  of  the  rope  suspended  from  the  ceiling)  and  treads  the 
sand  in  with  his  feet.  The  surface  is  then  struck  off  level  with  a 
straight  metal  bar  or  scraper,  a  little  loose  sand  is  sprinkled  on 
the  surface,  upon  which  another  board  is  placed,  and  rubbed  down- 
close. 

The  two  boards  and  the  flask  contained  between  them  are  then 
all  three  turned  over  together.  This  requires  them  to  be  brought 
to  the  front  of  the  moulding-trough,  so  that  the  individual  may 
rest  his  chest  against  them,  and  his  fore-arms  upon  the  edges  of 
the  top  board ;  he  then  grasps  the  three  together  at  the  back  part 
with  his  outstretched  hands,  and,  thus  retained  in  contact,  the 
whole  are  quickly  turned  over  upon  the  front  edge  of  the  mould- 
ing-trough, and  then  slid  back  upon  the  transverse  bearers  or 
blocks  to  the  usual  position. 

The  top  board  is  afterwards  taken  off,  the  clean  surface  of  moist 
sand,  then  exposed,  is  well  dusted  over  with  red  brick-dust,  crushed 


CASTING  AND   FOUNDING.  243 

fine,  and  contained  in  a  linen  bag.  The  mouth  of  the  bag  is  held 
in  the  right  han,d,  and  the  bottom  corner  in  the  left,  and  both  hands 
are  shaken  up  and  down  together  to  scatter  the  dry  powder  uni- 
formly over  the  flask.  A  part  of  the  loose  powder  is  removed 
with  the  hand-bellows,  and  the  bottom  half  of  the  mould  is  then 
ready  for  receiving  the  patterns. 

The  models  are  next  arranged  upon  the  face  of  the  sand  at  4, 
so  as  to  leave  space  enough  to  prevent  the  parts  breaking  one  into 
the  other,  and  also  for  the  passages  by  which  the  metal  is  to  be 
introduced,  and  the  air  allowed  to  escape.  When  there  are  only 
two  or  three  pieces  to  be  cast,  a  separate  runner  is  often  made  to 
each  of  them  from  one  of  the  holes  in  the  end  of  the  flask.  When 
several  small  patterns  are  to  bo  moulded,  they  are  arranged  on 
both  sides  a  central  runner,  or  ridge,  from  which  small  passages 
lead  into  every  section  of  the  mould.  The  whole  mass  when 
poured  has  been  compared  to  a  great  fern  leaf  with  its  leaflets,  and 
is  usually  called  a  spray. 

Those  patterns  which  are  cylindrical  or  thick,  are  partly  sunk 
in  the  sand  by  scraping  out  hollow  recesses  with  the  bowl  of  an 
old'  copper  spoon,  and  knocking  the  model  into  the  sand  with  the 
mallet.  Afterwards  the  general  surface  is  repaired  to  agreement 
with  the  diametrical  line  of  the  model,  or  its  largest  section,  as  the 
case  may  be,  by  means  of  a  knife  or  a  little  piece  of  sheet  steel, 
something  like  the  worn-out  blade  of  a  desert-knife  bent  up  a  little 
at  the  end,  or  else  with  very  small  trowels. 

After  the  sand  is  made  good  to  the  edges  of  the  patterns,  the 
brick-dust  is  again  shaken  over  them,  so  that  the  patterns  may 
receive  a  slight  share  as  well  as  the  general  surface  of  the  sand. 
The  upper  part  of  the  flask  2,  3,  is  then  fitted  to  the  lower,  or  4, 5, 
by  the  pins,  and  this  half  likewise  is  made  up.  First  a  little  strong 
sand  is  sifted  in ;  it  is  then  filled  up  from  the  trough,  rammed 
down,  and  struck  off  as  before,  the  dry  powder  serving  to  prevent 
the  two  halves  from  sticking  together. 

In  order  to  open  the  mould  for  the  extraction  of  the  models,  a 
board  is  placed  on  the  top  of  flask  2,  3,  and  struck  smartly  at  dif- 
ferent parts  with  the  mallet ;  the  tool  is  then  laid  aside  and  the 
upper  part  of  the  flask  and  its  board  are  lifted  up  very  gently  and 
quite  level,  after  which  it  is  inverted  on  its  board — and  now  each  of 
the  inner  faces  of  the  mould  is  exposed.  Should  it  happen  that 
any  considerable  portion  of  the  mould,  say  a  part  as  large  as  a 
shilling,  is  broken  down  in  one  piece,  the  cavity  is  moistened  with 
the  end  of  the  knife,  the  mould  is  again  carefully  closed,  and 
lightly  struck  before  the  removal  of  the  patterns.  It  is  probable 
on  the  second  lifting  such  piece  will  be  picked  up.- 

The  breaks  are  carefully  repaired  before  the  extraction  of  the 
patterns,  to  effect  which  they  are  driven  slightly  sideways  with 
blows  of  the  mallet,  given  on  a  short  wire  or  punch,  so  as  to  loosen 
them  by  enlarging  the  space  around  them.  The  patterns  are  then 
lifted  out  very  carefully  with  the  finger-nails,  or  sometimes  a 


244  THE   PRACTICAL   METAL-WORKER  S   ASSISTANT. 

pointed  wire  is  driven  a  little  way  into  the  pattern  to  serve  as  a 
handle  to  lift  it  by.  This  process  requires  some  delicacy  not  to 
tear  away  the  sand,  which  accident  must  be  carefully  repaired, 
sometimes  by  replacing  the  loose  pieces,  at  other  times  with  a  little 
new  sand  picked  out  of  any  unused  part  of  the  mould. 

A  steel  wire,  pointed  and  hardened,  is  convenient  as  a  picker  out. 
and  when  fixed  in  the  pattern  and  stuck  sideways  it  serves  as  a 
loosening  bar  likewise. 

Should  the  flask  only  contain  one  or  two  objects,  the  ingate  or 
runner  is  now  scooped  out  of  the  sand,  so  as  to  lead  from  the 
object  to  the  pouring  hole,  and  when  several  objects  are  contained, 
a  large  central  channel,  and  lesser  passages  sideways,  are  made  as 
before  mentioned.  The  entrance  round  about  the  pouring  hole  is 
smoothed  and  compressed  with  the  thumb  that  it  may  not  break 
down  when  the  metal  is  poured,  and  all  the  loose  sand  is  care- 
fully blown  out  of  the  mould,  both  parts  of  which  may  be  placed 
edgeways  for  the  more  convenient  application  of  the  bellows  if 
necessary. 

The  succeeding  processes  are  to  dust  the  faces  of  both  halves  of 
the  mould  with  meal  dust  or  waste  flour,  as  explained  with  regard 
to  the  brick-dust,  and  to  replace  the  mould  and  boards.  The  whole 
of  them  are  then  carried  to  the  spill-trough,  upon  the  edge  of 
which  they  are  rested  whilst  the  one  board  is  placed  exactly  level 
with  the  end  of  the  flask,  but  the  board  on  the  side  from  which 
the  crucible  will  be  poured,  is  placed  about  two  inches  below,  as 
in  Fig.  140,  p.  238,  and  the  hand-screws  are  fixed  on  as  shown. 
The  mould  is  now  held  mouth  downwards,  that  any  sand  loosened 
in  the  screwing  down  may  be  allowed  to  fall  out,  and  the  flask, 
according  to^ts  size,  is  supported  either  on  the  ground  or  on  the 
surface  of  the  trough  by  aid  of  a  little  bar  resting  against  the 
clamp.  It  is  now  quite  ready  to  be  filled — the  particulars  of 
which  process  will  be  described  when  the  remarks  on  moulding 
are  concluded. 

In  works  that  require  the  first  side  or  3,  4  to  be  cut  away  for 
embedding  the  models,  it  is  usual  when  the  second  part  or  2,  3  has 
been  made,  to  destroy  the  first  or  fake  side  (which  is  only  hastily 
made),  and  to  repeat  it  in  a  more  careful  manner  by  inverting  the 
lower  flask  upon  2,  3,  proceeding  in  all  other  respects  as  before, 
by  which  means  a  much  more  accurate  and  sound  mould  is  pro- 
duced. 

When  many  copies  of  the  same  patterns  are  required,  an  odd  side 
is  prepared,  that  is,  a  flask  is  chosen  to  which  there  are  two  bottom 
sides,  4,  5.  One  of  these  latter  is  very  carefully  arranged  with  all 
the  patterns,  but  which  are  only  embedded  larely  half  way,  so  that 
when  2,  3,  is  filled  and  both  are  turned  over,  the  whole  of  the  pat- 
terns are  left  in  the  new  side ;  a  second  side,  4,  5,  is  moulded  to 
serve  for  receiving  the  metal,  as  the  mould  is  destroyed  every  time 
the  metal  is  poured  in.  By  this  plan  the  trouble  of  re-arranging 
the  patterns  for  every  separate  mould  is  saved,  as  they  are  merely 


CASTING   AND   FOUNDING.  245 

replaced  in  the  odd  side,  and  the  routine  of  forming  the  two  work- 
ing sides  is  repeated. 

MOULDING  CORED  WORKS. — If  the  objects  to  be  cast  require  to  be 
so  moulded  that  when  they  leave  the  sand  they  may  contain  one  or 
several  holes,  they  are  said  to  be  cored,  and  in  such  cases,  a  variety 
of  methods  are  practised  for  introducing  internal  moulds  or  cores, 
which  shall  intercept  the  flow  of  the  metal,  and  prevent  it  from 
forming  one  solid  mass  at  those  respective  parts.  For  example, 
the  pins  inserted  in  the  pewterers'  moulds,  Figs.  127  and  130, 
page  234,  for  producing  the  holes  in  the  joints,  are  essentially 
cores.  Various  other  methods  are  pursued,  the  three  most  usual 
of  which  are  represented  in  Figs.  141,  142,  and  143  :  the  upper  fig- 
ures show  the  exact  sections  of  the  three  models  or  casting  pat- 
terns ;  the  lower  figure  represents  the  two  halves  of  the  mould, 
which  are  respectively  shaded  with  perpendicular  and  horizontal 
lines,  the  cores  are  shaded  obliquely ;  and  the  white  open  spaces 
show  the  hollows  to  be  occupied  by  the  metal  when  it  is  poured  in. 

First.  Many  works  are  said  to  deliver  their  own  cores ;  of  such 
kind  is  Fig.  141,  in  which  the  cavity  extends  through  the  model, 
and  exactly  represents  that  which  is  required  in  the  casting ;  the 
hole  is  either  made  quite  parallel,  or  a  little  larger  one  side  than 
the  other,  and  gradually  taper  between  the  two.  In  some  cases, 
when  the  hole  is  sufficiently  taper,  it  delivers  its  own  core  as  a  con- 
tinuation of  the  general  mass  of  sand  filling  the  one  side  of  the  flask ; 
but  in  many  or  most  cases,  the  space  in  the  model  is  rammed  full  of 
strong  sand  at  first,  and  it  is  then  moulded  as  if  to  produce  a  plain 
solid  casting.  Before  the  mould  is  finally  closed  for  pouring,  the 
sand  core  is  pushed  carefully  out  of  the  pattern,  and  inserted  in  the 
mould ;  to  denote  its  precise  position,  one  side  of  the  core  is  scored 
with  one  or  two  deep  marks  in  the  first  instance,  which  cause 
similar  ridges  or  guides  in  the  mould. 

Secondly.  When  the  hole  extends  only  part  way  through,  the 
hole  of  the  pattern,  Fig.  142,  is  fitted  with  a  solid  plug,  sawn  and 
filed  out  of  soft  unburnt  brick,  principally  sand  (or  the  common 


Figs.  141  142  143. 


Flanders  brick),  the  core  is  made  long  enough  to  project  about  as 
much  as  its  own  diameter,  and  the  work  is  moulded  as  if  to  be 
cast  with  a  solid  pin,  instead  of  a  hole.  The  last  step  is  to  extract 


246 


THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 


the  filed  core,  and  to  insert  it  into  the  hollow  formed  by  itself  in 
the  flask. 

Thirdly.  The  patterns  for  iron  work  and  some  others  are  mostly 
made  with  prints  instead  of  holes,  as  in  Fig.  143 ;  that  is,  the  pat- 
tern-maker places  square  or  round  pieces  on  one  or  both  sides  of 
the  pattern,  where  the  square  or  round  holes  are  respectively 
required ;  and  the  founder  has  moulds  for  forming  cores  of  corres- 
ponding diameters  or  sections,  and  in  lengths  of  about  two  to  twelve 
inches ;  short  pieces  of  which  are  cut  off  as  may  be  required. 

For  example;  some  core-boxes  are  made  like  Fig.  144,  for  cylin- 
drical cores ;  these  divide  through  the  axis,  and  are  kept  in  posi- 
tion by  pins ;  at  the  time  when  they  are  rammed  they  are  fixed 
together  by  wood  or  iron  staples,  embracing  three  sides  of  the 
mould,  or  else  by  screw  clamps.  For  straight  cores,  say  one  inch 
wide,  twelve  inches  long,  and  half-inch  thick,  the  pieces  of  wood, 
Fig.  145,  are  also  one  inch  thick,  with  an  opening  between  them 
of  twelve  inches  long  and  half-inch  wide.  This  core-box  is  laid 
on  a  flat  board,  it  is  also  held  together  with  clamps,  but  without 
pins  in  the  core-box,  as  the  projection  at  the  one  end  gives  the 
position ;  it  is  rammed  flush  with  both  sides,  and  the  two  parts  can 
be  then  separated  obliquely.  If  it  is  preferred  to  make  the  cores 
to  the  precise  lengths  instead  of  cutting  them  off,  this  core-box 
admits  of  contraction  in  length,  in  the  manner  of  the  type  mould, 
Fig.  136,  p.  235,  and  by  placing  thin  slips  between  the  two  halves 
it  may  be  temporarily  increased  in  width  but  not  in  thickness. 
Fig.  146  is  a  similar  core-box  for  a  casting  with  circular  mortises  ; 
this  requires  pins  or  projections  at  each  end,  as  it  cannot  be  opened 
obliquely.  Core-boxes  are  sometimes  made  of  plaster  of  Paris, 
wood  is  much  better,  and  metal  is  the  best  of  all. 

Many  works  require  core-boxes  to  be  made  expressly  for  them ; 
thus  the  dotted  line  in  Fig.  144  shows  an  enlargement  in  the  centre 
for  coring  a  hole  of  that  particular  section.  Figs.  147  and  148 
represent  the  two  halves  of  a  brass  or  lead  core-box  suitable  to  the 


Figs.  144 


146 


150  149     148    147. 


stop-cock,  Fig.  149  ;  and  Fig.  150  shows  the  core  itself  after  its 
removal  from  the  part  148  in  which  it  is  also  figured.     In  149,  the 


CASTING   AND    FOUNDING. 


247 


model  from  which  the  object  is  moulded,  the  shaded  parts  repre- 
sent the  projections,  or  core-prints,  which  imprint  within  the  mould 
the  places  where  the  extremities  of  the  core,  Fig.  150,  are  sup 
ported  when  placed  therein. 

The  various  kinds  of  core-boxes  are  rammed  full  of  new  sand, 
sometimes  with  extra  loam;  the  long  cores  are  strengthened  by. 
wires ;  they  are  carefully  removed  from  the  boxes  and  thoroughly 
drjed  before  use,  in  the  oven  prepared  for  the  purpose. 

Others  perfer  sand,  horse-dung,  and  a  very  little  loam,  for  mak- 
ing cores ;  these  are  dried,  and  then  well  burned,  for.which  purpose 
they  are  put  into  an  empty  crucible  within  the  fire,  the  last  thing 
at  night,  and  allowed  to  remain  until  the  morning.  This  consumes 
the  small  particles  of  straw,  and  renders  them  more  porous,  in 
consequence  of  which  the  works  become  sounder  from  the  free 
escape  of  air,  the  necessity  of  which  was  adverted  to  in  the  earlier 
part  of  this  subject,  and  cannot  be  too  much  insisted  upon. 

Fig.  151  represents  several  examples  of  coring :  in  this  view  the 
works  are  represented  of  their  ultimate  forms,  that  is,  with  the 
holes  in  them;  in  Fig.  152,  the  models  are  arranged  in  the  flask, 

Fig.  151 


with  the  runners  all  prepared,  the  prints  of  the  cores  being  in  every 
case  shaded  for  distinction.  Thus  a  is  the  stopcock,  of  which  ex- 
planation has  been  already  given ;  b,  has  a  straight  and  a  circular 
mortise ;  this  pattern  delivers  its  own  core,  in  the  manner  referred  to 
in  Fig.  141,  as  the  model  is  made  with  mortises  like  the  finished 
work:  c  only  requires  a  perpendicular  square  core;  d,  a  round  coro 
parallel  with  the  face  of  the  flask,  and  in  this  manner  all  tubes  and 
sockets  are  cast  whether  of  uniform  or  irregular  bore,  see  Fig.  144; 
e,  has  two  rectangular  cores  crossing  each  other  at  right  angles : 


248  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

and  /  is  the  cap  of  a  double-acting  pump,  the  core  for  which  is 
shown  in  section  by  the  white  part  of  Fig.  152  J,  the  shaded  portions 
being  the  metal :  the  great  aperture  leads  to  the  piston,  the  two 
smaller  are  for  valves  opening  inwards  and  outwards;  this  of 
course  requires  a  metal  core-box  capable  of  division  in  two  parts, 
and  made  exactly  to  the  particular  form. 

In  addition  to  the  cores  used  for  making  holes  and  mortises, 
much  ingenious  contrivance  is  displayed  in  the  cores  employed 
for  other  works  of  every-day  occurrence,  the  undercut  parts  of 
which  would  retain  them  in  the  sand  but  for  the  employment  of 
these  and  analogous  contrivances.  It  will  be  now  readily  under- 
stood that  if,  in  the  Fig.  122,  p.  232,  the  parts  shaded  obliquely 
were  separate,  there  would  be  no  difficulty  in  removing  first  the 
upper  half  of  the  flask,  the  false  cores,  after  which  the  patterns 
would  be  quite  free.  The  term/afoe  core  is  employed  by  the  brass- 
founder  to  express  the  same  thing  as  the  drawback  of  the  iron- 
founder.  The  former  calls  every  loose  piece  of  the  mould  not 
intended  for  holes,  a  false  core.  By  such  a  method,  however,  the 
circular  edge  of  a  sheave  would  require  at  least  three  such  pieces, 
but  Fig.  153  shows  a  different  way  of  accomplishing  the  same 


thing,  when  the  pattern  is  made  in  two  parts  in  the  manner  repre- 
sented. 

The  entire  model  is  first  knocked  into  the  side  A,  the  sand  is 
cut  away  to  the  inner  margin  of  the  pattern  which  terminates 
upon  the  dotted  line  a,  and  the  side  A,  of  the  mould  is  then  well 
dusted;  a  layer  of  sand  is  now  thrown  on,  and  rammed  tolerably 
firm  to  form  an  annular  core,  which  is  made  exactly  level  with  the 
inner  margin  b  of  the  pattern,  and  the  core  is  well  dusted ;  lastly, 
the  side  B  is  put  on  and  rammed  as  usual.  To  extract  the  model, 
the  side  B  is  first  lifted,  the  half  pattern  b,  b,  (which  is  shaded,)  is 
removed,  and  the  ingate  is  cut  in  the  side  B,  to  the  edge  of  the 
pully ;  the  mould  is  well  dusted  with  flour  and  replaced. 

The  entire  mould  is  now  turned  over,  A  is  first  removed,  then 
the  remaining  half  pattern  a,  a,  which  must  be  touched  very  ten- 
derly or  it  will  break  down  the  core;  and  the  runner,  (which 
divides  in  two  branches  around  the  core),  is  also  scooped  out  in  the 
side  A,  which  is  dusted  with  flour  and  replaced,  ready  for  pouring. 
Common  patterns  not  requiring  cores  are  frequently  divided  into 


CASTING  AND    FOUNDING.  249 

two  parts  in  the  above  manner,  so  that  when  the  mould  is  open 
the  pattern  may  divide  and  remain  half  in  each  side ;  this  lessens 
the  risk  of  breaking  down  the  mould  and  the  attendant  trouble  of 
afterwards  repairing  it. 

REVERSING  AND  FIGURE  CASTING.— Supposing  that  an  orna- 
ment, represented  in  section  in  Fig.  154  has  been  modeled  in  relief, 
either  in  clay  or  wax  upon  a  flat  board,  from  which  a  thin  casting 
in  brass  is  wanted  without  the  tablet,  the  process  is  called  revers- 
ing, and  is  to  be  accomplished  in  any  of  three  ways. 

First  an  empty  flask  is  placed  upon  the  board,  154,  and  rammed 
full  of  sand ;  it  assumes  the  appearance  of  155  ;  the  second  part 
of  the  flask  is  attached  to  155  and  filled  to  make  the  part  156, 
which  is  called  the  back-mould ;  some  clay  is  then  rolled  out  to  the 
intended  thickness  of  the  casting,  with  a  cylindrical  roller  running 
on  two  slips  of  wood  or  on  two  1 

wires,  and  a  narrow  band  of  this  ,—^s — -~^~    "X.. gs* 

clay  is  placed  on  156,  round  the     I  I  15* 

figure,  that  it  may  separate  155 

and  156,  exactly  to  the  required 

distance,  ready  for  receiving  the 

metal. 

By  the   second   mode,  155  is 


first  made,  then  156,  and  from  the 
latter  157  is  moulded,  which  is  a 
counterpart  of  155.  A  thin  sheet 


counterpart  01  LOO.  A.  turn  saeeu  cpwjj 
of  clay  is  then  pressed  all  over  [i  •  „.  ^^-^=^^ 
157,  into  every  cavity,  and  cut  oft' 
flush  with  the  plane  surface  of  the  mould,  by  which  it  assumes  the 
appearance  denoted  by  the  double  line  in  157.  After  this  156 
is  destroyed,  and  made  over  again  in  157,  but  so  much  smaller 
than  before  as  the  thickness  of  the  clay  lining;  when  the  new 
back-mould,  156,  is  placed  in  contact  with  155,  it  leaves  the  re- 
quired space  for  the  intended  casting.  This  mode  is  only  prefer 
able  to  the  first,  when  many  parts  of  the  work  are  nearly  perpen- 
dicular; in  which  case,  if  the  first  mode  be  adopted,  a  portion  of 
the  back  mould  155  must  be  pared  away  at  the  perpendicular 
parts,  and  if  incautiously  performed  there  will  be  a  risk  of  irregu- 
larity of  thickness,  or  even  of  holes  in  the  casting. 

The  third  mode  is  to  take  a  casting  of  154  in  plaster  of  Paris ; 
when  this  is  thoroughly  dry  it  is  oiled,  and  poured  full  of  a  cement 
of  wax,  grease,  and  red-ochre,  which  is  poured  out  again  when  par- 
tially sot,  leaving  a  thin  crust  behind  (as  in  the  pewter  handle).  A 
second,  a  third,  or  more  layers  of  wax  are  thus  added  until  the 
whole  is  sufficiently  thick,  when  the  wax  shell  is  extracted,  and 
then  moulded  from  in  the  ordinary  manner ;  the  first  brass  casting 
is  finished  and  chased  to  serve  as  the  permanent  pattern.  The 
management  of  the  wax  requires  practice. 

In  constructing  such  moulds  additional  care  is  given  to  every 
part  of  the  work ;  for  example,  the  sand  is  sifted  much  finer,  the 


250  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

parting  is  made  with  fine  charcoal  dust,  and  the  facing  with  char- 
coal and  rottenstone  mixed  together  in  about  equal  parts,  the  mix- 
ture beinw  of  a  slaty  color;  sometimes  the  loamstone,  which  is 
found  in  the  pits  where  clay  for  making  tiles  is  dug,  is  used  instead 
of  rottenstone.  The  moulds  are  well  dried  in  an  oven,  or  over  the 
mouth  of  the  furnace,  and  the  faces  are  afterwards  smoked  over  a 
dull  fire  of  cork  shavings  ;  this  deposits  a  very  fine  layer  of  soot 
over  the  face  of  the  mould,  which  greatly  assists  the  running  of 
the  metal;  when  this  additional  care  is  taken  the  works  are  known 
as  fine-castings. 

In  casting  figures,  such  as  busts,  animals,  and  ornaments  consist- 
ing of  branches  and  foliage,  considerably  more  skill  is  required  : 
the  originals  are  generally  solid,  but  the  moulds  necessarily  divide 
into  very  many  parts.  Most  persons  will  have  had  the  opportunity 
of  judging  of  the  complexity  of  these  moulds,  from  similar  works 
in  plaster  of  Paris,  which  are  frequently  purchased  by  artists  and 
the  virtuosi  before  the  seams  of  the  mould  are  removed. 

A  glance  at  these  plaster-casts,  at  the  complex  and  undercut 
form  of  many  of  these  ornamental  works,  and  at  the  explanatory 
diagram  on  page  231,  will  convey  some  notion  of  the  method  to 
be  pursued  as  well  as  of  the  trouble  attending  them.  It  is  shown 
for  example,  by  the  diagram  just  referred  to,  that  all  figured 
works  approaching  to  the  circular  or  elliptical  section,  require  that 
the  mould  should  be  divided -in to  at  least  three  parts,  except  under 
most  favorable  circumstances.  In  the  human  figure  and  quadru- 
peds, the  four  limbs  and  the  trunk  require  at  least  three  parts  each, 
and  often  many  more ;  it  will  be  easily  conceived  therefore  that 
such  moulded  works  require  considerable  skill  and  patience. 

Piece  after  piece  of  the  mould  is  successively  produced,  just  as 
in  making  the  core,  Fig.  153,  p.  248,  every  piece  embracing  only 
so  much  of  the  figure,  as  in  no  part  to  require  any  core  to  over- 
hang the  line  in  which  it  is  withdrawn.  The  side  of  the  mould  in 
which  the  figure  is  partly  embedded  is  first  dusted  with  charcoal, 
and  then  the  first  core  is  very  carefully  rammed  into  the  nook, 
and  pared  down  to  the  new  line  of  division;  the  green  or  wet 
sand  core  is  then  dusted,  and  the  second  core  is  made,  and  after- 
wards dusted,  when  the  moulder -proceeds  with  the  third  core  and 
so  on  ;  every  one  being  carefully  adapted  to  its  neighbor,  and  with- 
drawn to  see  that  all  is  right,  before  the  succeeding  core  is  pro- 
ceeded with.  The  relative  positions  of  the  cores  amongst  them- 
selves are  readily  recognized  and  maintained  by  the  irregularity 
of  their  forms,  as  in  a  child's  dissected  map,  or  by  making  a  notch 
or  two  here  and  there,  which  are  faithfully  copied  in  the  succeed- 
ing piece.  It  is  frequently  necessary  to  thrust  two  or  more  broken 
needles  through  the  green  cores  into  the  neighboring  parts  to  con- 
nect them  together,  in  imitation  of  the  pins  in  the  flasks. 

All  the  parts  of  the  mould  are  dried  in  the  oven,  and  the  facings 
are  smoked  over  a  cork  fire  as  before  explained ;  the  perfection  of 
the  casting  is  augmented  by  pouring  whilst  the  mould  is  still 


CASTING   AND   FOUNDING.  251 

slightly  warm,  as  otherwise  on  cooling  it  has  an  increased  affinity 
for  damp ;  but  the  mould  when  hot  is  more  or  less  filled  with 
aqueous  vapor,  which  is  equally  prejudicial. 

When  a  figure,  such  as  a  bust,  is  required  to  be  cast  hollow  from 
a  solid  model,  it  is  first  moulded  exactly  as  above.  The  core  is 
now  produced  as  follows :  at  the  foot  of  the  bust  a  large  space, 
nearly  equal  in  length  and  bulk  to  the  bust,  is  cut  away  in  the  sand, 
to  serve  for  fixing  the  core  in  the  mould,  or  for  the  balance,  as  it  is 
called,  as  the  core  cannot  be  propped  up  at  both  ends.  The  entire 
hollow,  that  is  for  the  bust  and  the  balance,  is  filled  with  a  com- 
position of  about  one  part  of  plaster  of  Paris  and  two  of  sand  or 
fine  brick-dust,  mixed  with  a  little  water  and  poured  in  fluid,  a  few 
wires  being  placed  amidst  the  same  for  additional  support. 

The  mould  is  now  taken  to  pieces  to  extract  the  core,  which  is 
then  dried,  thoroughly  burned,  and  allowed  to  cool  slowly  (which 
the  founder  calls  annealing,  from  a  similar  method  being  employed 
in  annealing  or  softening  the  metals  and  glass) :  the  core  is  then  re- 
turned to  the  mould,  to  see  that,  it  has  not  become  distorted.  If 
needful  the  fitting  around  the  balance  is  made  good  to  suit  the  re- 
duced magnitude  of  the  core,  which  latter  is  then  so  far  pared  away 
as  to  leave  room  for  the  thickness  of  metal ;  this  is  frequently  regu- 
lated by  boring  holes  at  many  parts  of  the  core  with  a  stop-drill, 
having  a  collar  to  prevent  its  penetrating  beyond  the  determined 
depth ;  the  surface  of  the  core  is  now  pared  down  to  the  bottoms 
of  the  holes,  as  uniformly  as  possible.  When  the  mould  has  been 
faced,  dried  and  smoked,  the  whole  is  put  together  for  pouring,  for 
which  purpose  the  figure  is  inverted  and  filled  from  the  pedestal. 

Equestrian  and  other  figures  are  sometimes  cast  in  two,  three,  or 
more  pieces,  and'joined  together  by  solder,  screws,  or  wires ;  but  in 
all  such  works,  the  aim  of  the  founder  is  to  leave  little  or  nothing 
for  the  finisher  or  chaser  to  do. 

Some  objects  which  are  either  exceedingly  complex  in  their 
form,  or  soft  and  flexible  in  their  substance,  and  which  do  not 
therefore  admit  of  being  moulded  in  sand,  in  the  ordinary  manner 
of  figure  casting,  may  be  moulded  for  a  single  copy,  provided  the 
originals  consist  of  substances  which  may  be  either  readily  melted 
or  burned  into  ashes. 

A  cavity  is  made  in  the  sand  of  the  moulding-trough,  a  little 
larger  and  longer  than  the  object,  or  else  a  wooden  box  of  appro- 
priate size  is  procured,  in  the  midst  of  which  the  wax  model  may 
be  placed ;  to  the  end  of  the  model  is  added  a  piece  to  represent 
the  runner,  which  will  be  required  for  introducing  the  metal.  The 
composition  of  one-third  plaster  of  Paris  and  two-thirds  brick-dust, 
mixed  with  water,  the  same  as  for  the  core  of  the  bust,  is  then 
poured  in.  entirely  to  surround  the  model.  The  mould  is  first 
slowly  dried,  it  is  then  inverted  and  made  warm  to  allow  the  wax 
to  run  out,  after  which  it  is  annealed,  or  burned  to  redness,  and 
lastlv.  when  cooled,  it  is  buried  in  sand  and  filled  with  metal.  The 


252  THE    PRACTICAL    METAL-WOBKER  S   ASSISTANT. 

method  necessarily  throws  the  chance  of  success  upon  a  single  trial, 
as  the  model  is  destroyed. 

Should  the  face  of  the  casting  be  required  to  be  particularly 
smooth,  a  small  quantity  of  brick-dust  is  washed,  (in  the  manner 
practised  with  emery,  and  to  be  explained,)  and  mixed  with  very 
fine  plaster :  a  coat  of  this  is  brushed  over  the  model,  which  ex- 
cludes air-bubbles,  the  model  is  quickly  placed  in  its  cavity,  and 
the  coarser  mixture  is  poured  in  as  before. 

The  above  method  exactly  corroborates  a  mode  long  since  des- 
cribed as  being  suitable  to  casting  copies  of  small  animals  or  in- 
sects, parts  of  vegetables  and  similar  objects ;  these  are  to  be  fixed 
in  the  centre  of  a  small  box,  by  means  of  a  few  threads  attached  to 
any  convenient  parts,  one  or  two  wires  being  added  to  make  air- 
holes, and  ingates  for  the  metal.  A  small  quantity  of  river  silt  or 
mud,  which  had  been  carefully  washed,  was  first  thrown  in  and 
spread  around  the  object  by  swinging  the  box  about ;  and  when 
partly  dry,  successive  but  coarser  coats  were  thrown  in,  so  as  ulti- 
mately to  fill  up  the  box.  When  it  had  become  thoroughly  dry, 
the  wires  were  first  removed  from  the  earthy  mould ;  it  was  then 
burned  to  reduce  the  object  to  ashes,  and  when  every  particle  of 
the  model  had  been  blown  out,  it  was  ready  to  be  filled  with 
metal. 

FILLING  THE  MOULDS. — Having  traced  the  formation  of  various 
kinds  of  moulds  for  brass  work,  we  must  now  return  to  the  fur- 
nace to  see  if  the  metal  is  in  condition  to  be  poured,  which  is  in- 
dicated by  the  slight  wasting  of  the  zinc  from  its  surface  with  a 
lambent  flame.  When  this  condition  is  observed,  the  large  cokes 
are  first  removed  from  the  mouth  of  the  pot,  and  a  long  pair  of 
crucible  tongs  are  thrust  down  beside  the  same  to  embrace  it 
securely,  after  which  a  coupler  is  dropped  upon  the  handles  of  the 
tongs :  the  pot  is  now  lifted  out  with  both  hands  and  carried  to 
the  skimming-place,  where  the  loose  dross  is  skimmed  off  with 
an  iron  rod,  and  the  pot  is  rested  upon  the  spill-trough,  against 
or  upon  which  the  flasks  are  arranged. 

The  temperature  at  which  the  metal  is  poured  must  be  propor- 
tioned to  the  magnitude  of  the  works:  thus  large,  straggling,  and 
thin  castings  require  the  metal  to  be  very  hot,  otherwise  it  will  be 
chilled  from  coming  in  contact  with  the  extended  surface  of  sand 
before  having  entirely  filled  the  mould ;  thick  massive  castings  if 
filled  with  such  hot  metal  would  be  sand-burned,  as  the  long  con- 
tinuance of  the  heat  would  destroy  the  face  of  the  mould  before 
the  metal  would  be  solidified. 

The  line  of  policy  seems  therefore  to  be,  to  pour  the  metals  at 
that  period  when  they  shall  be  sufficiently  fluid  to  fill  the  moulds 
perfectly  and  produce  distinct  and  sharp,  impressions,  but  that  the 
metal  shall  become  externally  congealed  as  soon  as  possible  after- 
wards. 

For  slight  moulds  the  carbonaceous  facings,  whether  meal-dust- 
charcoal,  or  soot,  are  good,  as  these  substances  are  bad  conductors, 


CASTING   AND    FOUNDING.  253 

of  heat,  and  rather  aid  than  otherwise  by  their  ignition  ;  it  is  also 
proper  to  air  these  moulds  for  thin  works,  or  slightly  warm  them 
before  a  grate  containing  a  coke  fire.  But  in  massive  works  these 
precautions  are  less  required ;  and  the  facing  of  common  brick- 
dust,  which  is  incombustible  and  more  binding,  succeeds  better. 

The  founder  therefore  fills  the  moulds  having  the  slightest  works 
first,  and  gradually  proceeds  to  the  heaviest ;  if  needful  he  will 
wait  a  little  to  cool  the  metal,  or  will  effect  the  same  purpose  by 
stirring  it  with  one  of  the  ridges  or  waste  runners,  which  thereby 
becomes  partially  melted.  He  judges  of  the  temperature  of  the 
melted  brass,  principally  by  the  eye,  as  when  out  of  the  furnace 
and  very  hot,  the  surface  emits  a  brilliant  bluish  white  flame,  and 
gives  off  clouds  of  the  white  oxide  of  zinc,  a  considerable  portion 
of  which  floats  in  the  air  like  snow,  the  light  decreases  with  the 
temperature,  and  but  little  zinc  is  then  fumed  away. 

Gun-metal  and  pot-metal  do  not  flare  away  in  the  manner  of 
brass,  the  tin  and  lead  being  far  less  volatile  than  zinc ;  neither 
should  they  be  poured  so  hot  or  fluid  as  yellow  brass,  or  they  will 
become  sand-burned  in  a  greater  degree,  or  rather  the  tin  and  lead 
will  strike  to  the  surface,  as  noticed  at  page  212.  Gun-metal  and 
the  much  used  alloys  of  copper,  tin,  and  zinc,  are  sometimes  mixed 
at  the  time  of  pouring ;  the  alloy  of  lead  and  copper  is  never  so 
treated,  but  always  contains  old  rnetal,  and  copper  is  seldom  cast 
alone,  but  a  trifling  portion  of  zinc  is  added  to  it,  otherwise  the 
work  becomes  nearly  full  of  little  air-bubbles  throughout  its  surface.  > 

When  the  founder  is  in  doubt  as  to  the  quality  of  the  metal, 
from  its  containing  old  metal  of  unknown  character,  or  that  he 
desires  to  be  very  exact,  he  will  either  pour  a  sample  from  the  pot 
into  an  ingot  mould,  or  extract  a  little  with  a  long  rod  terminating 
in  a  spoon  heated  to  redness.  The  lump  is  cooled  and  tried  with 
the  file,  saw,  hammer,  or  drill,  to  learn  its  quality. 

The  engraved  cylinders  for  calico-printing  are  required  to  be  of 
pure  copper,  and  their  unsoundness  when  cast  in  the  usual  way, 
was  found  to  be  so  serious  an  evil  that  it  gave  rise  to  casting  the 
metals  under  pressure. 

Some  persons  judge  of  the  heat  proper  for  pouring,  by  apply- 
ing the  skimmer  to  the  surface  of  the  metal;  which  when  very  hot 
has  a  motion  like  that  of  boiling  water;  this  dies  away  and  be- 
comes more  languid  as  the  metal  cools.  Many  works  are  spoiled 
from  being  poured  too  hot,  and  the  management  of  the  heat  is 
much  more  difficult  when  the  quantity  of  metal  is  small. 

The  mixture  and  temperature  of  the  metal  being  found  to  be 
proper,  it  is  poured  in  the  manner  represented  in  Fig.  119,  p.  221 . 
the  tongs  are  gradually  lowered  from  the  shoulder  down  the  left 
arm,  and  the  right  hand  is  employed  in  keeping  back  the  dross 
,  from  the  lip  of  the  melting-pot.  A  crucible  containing  the  gen- 
'  eral  quantity  of  40  or  50  Ibs.  of  metal,  can  be  very  conveniently 
managed  by  one  individual,  but  for  larger  quantities,  sometimes 
amounting  to  one  hundred  weight,  an  assistant  aids  in  supporting 


254  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

the  crucible,  by  catching  hold  of  the  shoulder  of  the  tongs  with  a 
grunter,  an  iron  rod  bent  like  a  hook. 

Whilst  the  mould  is  being  filled,  there  is  a  rushing  or  hissing 
sound  from  the  flow  of  the  metal  and  the  escape  of  the  air ;  the 
effect  is  less  violent  where  there  are  two  or  more  passages,  as  in 
heavy  pieces,  and  then  the  jet  can  be  kept  entirely  full,  which  is 
desirable.  Immediately  after  the  mould  is  filled,  there  are  gener- 
ally small  but  harmless  explosions  of  the  gases,  which  escape 
through  the  seams  of  the  mould;  they  ignite  from  the  runners, 
and  burn  quietly ;  but  when  the  metal  blows,  from  the  after-escape 
of  any  confined  air,  it  makes  a  gurgling  bubbling  noise,  like  the 
boiling  of  water,  but  much  louder,  and  it  will  sometimes  throw 
the  fluid  metal  out  of  the  runner  in  three  or  four  separate  spirts : 
this  effect,  which  mostly  spoils  the  castings,  is  much  the  most 
likely  to  occur  with  cored  works,  and  with  such  as  are  rammed  in- 
less  judiciously  hard,  without  being,  like  the  moulds  for  fine  cast- 
ings, subsequently  well  dried. 

The  moulds  are  generally  opened  before  the  castings  are  cold, 
and  the  founder's  duty  is  ended  when  he  has  sawn  off  the  ingates 
or  ridges,  and  filed  away  the  ragged  edges  where  the  metal  has 
entered  the  seams  of  the  mould ;  small  works  are  additionally 
cleaned  in  a  rumble,  or  revolving  cask,  where  they  soon  scrub  each 
.other  clean. 

Nearly  all  small  brass  works  are  poured  vertically,  and  the  run- 
ners must  be  proportioned  to  the  size  of  the  castings,  that  they 
may  serve  to  fill  the  mould  quickly,  and  supply  at  the  top  a  mass 
of  still  fluid  metal,  to  serve  as  a  head  or  pressure  for  compressing 
that  which  is  beneath,  to  increase  the  density  and  soundness  of  the 
casting.  Most  large  works  in  brass,  and  the  greater  part  of  those 
in  iron,  are  moulded  and  poured  horizontally. 

IRON-FOUNDERS'  FLASKS,  AND  SAND  MOULDS. — The  process  of 
moulding  works  in  sand  is  essentially  the  same  both  for  brass  and 
iron  castings ;  but  the  very  great  magnitude  of  many  of  the  latter 
gives  rise  to  several  differences  in  the  methods:  it  will  suffice, 
however,  to  advert  to  the  more  important  points  in  which  the  two 
practices  differ,  or  to  those  which  have  not  been  already  noticed  ;  I 
shall  therefore  commence  with  a  few  remarks  upon  the  flasks  and 
the  sand. 

In  the  greater  number  of  cases  the  iron-founder  moulds  and 
casts  his  work  horizontally,  with  the  flasks  lying  upon  the  ground  ; 
frequently  the  top  part  only  is  lifted  ;  and  in  the  largest  works  the 
lower  part  of  the  flask  is  altogether  omitted,  such  pieces  being 
moulded  in  the  sand  constituting  the  floor  of  the  foundry ;  in  these 
cases  the  position  of  the  upper  flask  is  denoted  by  driving  a  few 
iron  stakes  into  the  earth,  in  contact  with  the  internal  angles  of  the 
lugs,  or  projecting  ears  of  the  flasks. 

The  sand  would  drop  out  of  such  large  flasks,  if  only  supported 
around  the  margin ;  they  are  consequently  made  with  cross-bars  or 
wooden  stays  a  few  inches  asunder,  which,  unless  the  entire  flask  is 


CASTING   AND   FOUNDING.  255 

made  of  wood,  are  fixed  by  little  fillets  cast  in  the  solid  with  the 
sides  of  the  iron  flasks.  A  great  number  of  hooks  in  the  form  of 
the  letter  S,  but  less  crooked  at  the  ends,  are  driven  into  the  bars, 
and  both  the  bars  and  hooks  are  wetted  with  thick  clay  water,  so 
that  the  sand  becomes  entangled  amidst  them,  and  is  sustained  when 
the  flask  is  lifted.  Some  flasks  require  the  force  of  either  two  or 
several  men,  who  raise  them  up  by  iron  pins  or  handles  projecting 
from  the  sides  of  the  flask ;  they  are  then  placed  upon  one  edge, 
and  allowed  to,  rest  against  any  convenient  support  whilst  they  are 
repaired,  or  they  are  sustained  by  a  prop. 

The  very  heavy  flasks  are  lifted  with  the  crane,  by  means  of  a 
transverse  beam  and  two  long  hangers,  called  dutches,  which  take 
hold  of  two  gudgeons  in  the  centres  of  the  ends  of  the  flask ;  it  can 
be  then  turned  round  in  the  slings,  just  the  same  as  a  dressing-glass, 
to  enable  it  to  be  repaired. 

The  modern  iron-founder's  flasks  are  entirely  of  iron,  and  do  not 
require  the  wooden  stays,  as  they  are  made  full  of  cross  ribs  nearly 
as  deep  as  the  flask  itself,  and  which  divide  its  entire  surface  into 
compartments  four  or  five  inches  wide,  and  one  to  two  feet  long. 
On  the  sides  of  every  compartment  are  little  fillets,  sloping  opposite 
ways,  so  as  to  lock  in  the  small  bodies  of  sand  very  effectually. 
When  these  top  flasks  are  placed  upon  middle  flasks  without  ribs, 
as  in  moulding  thick  objects,  the  two  parts  are  cottered  or  keyed 
together,  by  transverse  wedges  fixed  in  the  steady  pins  of  the  flask  ; 
lifters  or  gaggers  are  then  placed  amidst  the  sand ;  these  are  light 
T  shaped  pieces  of  iron,  wetted  and  placed  head  downwards,  the 
tails  of  which  are  largest  at  top,  so  as  to  hold  themselves  in  the 
sand,  the  same  as  the  key-stone  of  an  arch  is  supported.  The  gag- 
gers are  placed  at  various  parts  to  combine*  the  sand  in  the  two 
flasks,  and  they  fulfil  the  same  end  as  the  iron  hooks  and  nails 
driven  into  the  wooden  stays  of  the  old-fashioned  flasks. 

The  bottom  flask  or  drag  has  sometimes  plain  flat  cross-ribs  two 
inches  wide  (like  a  flat  bottom  with  square  holes),  that  it  may  be 
turned  over  without  a  bottom  board ;  and  unless  the  flasks  have 
swivels  for  the  crane,  they  have  two  cast-iron  pins  at  each  end,  and 
one  or  more  large  wrought-iron  handles  at  each  side,  by  which 
they  may  be  lifted  and  turned  over  by  a  proportionate  number  of 
men. 

The  sand  of  the  iron-founder  is  coarser  and  less  adhesive  than 
that  used  by  the  brass-founder.  The  parting  sand  is  the  burned 
sand  which  is  scraped  oft'  the  castings ;  it  loses  its  sharp,  crystal- 
line character  from  boing  exposed  to  the  red  heat.  The  facing- 
sand  is  sometimes  only  about  equal  parts  of  coal-dust  and  charcoal- 
dust,  ground  very  fine;  at  other  times,  either  old  or  new  sand  is 
added,  and  for  large  thick  works  a  little  road-drift  is  introduced. 
All  these  substances  get  largely  mixed  with  the  sand  of  the  floor, 
and  lessen  its  binding  quality,  which  is  compensated  for  by  occa- 
sional additions  of  new  sand,  and  by  using  more  moisture  with  the 
sand ;  as  before  extracting  the  patterns,  the  iron-founder  wets  the 


256  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

edges  of  the  sand  with  a  sponge,  which  has  sometimes  a  nail  tied 
to  it  to  direct  the  water  in  a  fine  stream ;  for  heavy  works  a  water- 
ing pot  is  used. 

The  green-sand  moulds  are  made,  as  in  the  brass-foundry,  of  the 
ordinary  stock  of  old  moist  sand ;  these  are  often  filled  as  soon  as 
they  have  been  made. 

The  dry-sand  moulds  are  made  in  the  same  manner,  but  with 
new  sand  containing  its  full  proportion  of  loam ;  these  moulds  are 
thoroughly  dried  in  a  large  oven  or  stove,  and  then  black- washed 
or  painted  with  thin  clay  water  containing  finely  ground  charcoal ; 
this  facing  is  also  thoroughly  dried  before  the  moulds  are  poured. 

The  loam  moulds^  which  are  much  used  for  iron  castings  and 
somewhat  also  for  fnose  of  brass,  are  made  of  wet  loam  with  a  little 
sand,  ground  together  irf  a  mill  to  the  consistence  of  mortar  ;  the 
moulds  are  made  partly  after  the  manner  of  the  bricklayer  and 
plasterer,  as  will  be  explained ;  the  loam  moulds  also  are  thoroughly 
dried,  black- washed,  and  again  dried,  as  from  their  greater  com- 
pactness they  allow  less  efficient  escape  for  the  vapor  or  air,  and 
therefore  they  must  be  put  into  the  condition  not  to  generate  much 
vapor  when  they  are  filled. 

Iron  moulds  are  also  employed  for  a  small  proportional  number 
of  works  which  are  then  called  chilled  castings  ;  these  were  referred 
to  at  pages  163  and  164 ;  and  occasionally  the  methods  of  sand  cast- 
ing and  chilling  are  combined,  as  in  some  axletree-boxes,  which  are 
moulded  from  wooden  patterns  in  sand,  and  are  cast  upon  an  iron 
core.  To  form  the  annular  recess  for  oil,  a  ring  of  sand,  made  in 
an  appropriate  core-box,  is  slipped  upon  the  iron  mandrel,  and  is 
left  behind  when  the  latter  is  driven  out  of  the  casting. 

It  would  be  a  useless  repetition  to  enter  into  the  details  of  mould- 
ing ordinary  iron  works ;  but  from  the  horizontal  position  of  the 
flasks  it  is  necessary  that  the  part  of  the  work  which  is  required  to 
be  the  soundest,  and  most  free  from  defects,  should  be  placed  down- 
wards, as  the  metal  is  more  condensed  at  the  lower  part,  and  free 
from  the  scoria  or  sullage  which  sometimes  renders  the  upper  sur- 
face very  rough  and  full  of  minute  holes.  As  the  flasks  almost 
always  lie  on  the  ground,  it  is  also  found  the  most  convenient  to 
retain  them  in  contact  by  placing  heavy  weights  upon  them ;  the 
foundry  should  in  consequence  have  an  abundant  supply  of  these. 

The  flasks  require  to  be  poured  through  a  hole  in  the  upper 
half,  as  seen  at  r,  Fig.  169,  page  259,  which  hole  is  formed  by 
placing  a  wooden  runner  slick  in  the  top  part  A,  whilst  it  is  being 
rammed ;  and  a  small  channel  is  afterwards  cut  sideways  into  the 
mould.  Sometimes  two,  three,  or  even  half-a-dozen  or  more  run- 
ners are  put  to  one  single  casting,  either  when  it  requires  a  great 
weight  of  metal,  or  when  it  is  large  but  slight,  as  in  trellis- work, 
in  which  case  the  metal  might  cool  before  filling  the  mould  if  only 
introduced  at  one  single  runner. 

When'the  runners  are  required  to  be  lofty,  either  to  supply  pres- 
sure to  the  metal,  or  as  a  reserve  to  fill  up  the  space  left  by  its  con- 


CASTING   AND   FOUNDING.  257 

traction  in  cooling,  iron  rings  of  six  or  eight  inches  diameter  are 
piled  up  to  the  required  height,  to  support  the  tube  of  sand  con- 
tained within  them.  Small  objects  that  are  poured  from  one  hole, 
are  frequently  moulded  with  two  runners,  that  the  metal  may  flow 
through  the  mould,  and  that  there  may  be  a  sufficient  supply  to 
meet  the  shrinkage,  and  also  to  supply  head  or  pressure ;  another 
advantage  also  results,  as  it  assists  in  carrying  oft'  the  scoria  or 
sullage. 

The  iron-founder  employs  all  the  methods  of  coring  explained  at 
pages  245  to  248,  and  also  others  of  an  entirely  different  kind  but 
little  required  in  brass- works ;  namely  for  lateral  holes  in  the  parts 
of  the  castings  buried  beneath  the  general  surface  of  the  mould, 
and  which  are  explained  by  the  Figs.  158  to  161.  Thus  158  repre- 
sents the  finished  casting,  159  the  model  of  the  same,  160  the  ap- 
pearance of  the  bottom  flask  or  drag  when  the  pattern  is  first  re- 
moved, and  161  the  flask  and  cores  when  closed  ready  for  pouring ; 
the  moulds  are  inverted,  and  the  same  letters  of  reference  refer  to 
similar  parts  of  all  these  figures. 


Figs.  158  159  d  160         a  161.    6 


The  core  print  a,  would  deliver  from  the  sand  and  leave  the 
cavity  at  a,  Fig.  160,  to  be  afterwards  filled  by  the  core  shown 
black  in  Fig.  161,  the  same  as  formerly  explained  at  Fig.  143,  p. 
245.  But  the  core  print,  b,  Fig.  159,  (which  has  reference  to  the 
black  stud  b,  Fig.  161,)  would  tear  away  the  sand  above  it  in  with- 
drawing the  pattern ;  therefore  the  print  b  should,  like  d,  Fig.  159, 
extend  to  the  face  of  the  pattern,  or  the  parting  line  represented  by 
e,  Fig.  161.  This  being  the  case,  the  pattern  would  leave  the  space 
denoted  at  d,  Fig.  160 ;  the  core  is  put  down  sideways  to  the  bot- 
tom of  the  recess,  and  extends  entirely  across  the  same ;  the  small 
open  space  above,  is  made  good  with  the  general  surface,  as  shown 
by  the  shade  lines  in  Fig.  161,  and  this  filling  in  at  the  same  time 
fixes  the  core  precisely  where  denoted  by  the  print  d,  which  latter 
has  a  mark  to  show  to  the  moulder  where  the  core  is  to  end.  The 
circular  hole  requires  the  core  print  shown  at  c,  Fig.  159  ;  the  cores 
themselves  are  made  in  the  core-boxes  144  and  145,  before  ex- 
plained at  page  246. 

Fig.  163  represents  the  model  and  core-print,  from  which  the 
finished  casting  shown  at  Fig.  162  might  be  made  from  a  solid  pat- 
tern in  a  two-part  flask ;  it  would  be  inverted,  and  the  parting 
would  be  made  upon  the  line,  x.  The  prints  for  the  four  holes  a  a, 
would  be  placed  in  the  top  flask,  and  those  for  the  great  apertures 
or  panels  d,  would  be  made  in  a  core-box  of  the  express  form,  and 
17 


258 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT 


as  thick  as  the  pattern  and  core-print  measured  together.  The 
core  would  be  deposited  edgeways  into  the  core-print,  and  the 
upper  corners  of  the  mould  would  be  made  good,  as  explained  in 
Fig.  JL61. 


Figs.  162 


164 


By  the  same  method,  a  mortise  wheel,  or  one  with  spaces  around 
its  edge,  as  at  ra  m,  Fig.  164,  to  be  filled  with  wooden  cogs,  might 
be  made  with  a  series  of  core-prints,  as  at  c,  brought  up  flush  with 
the  parting  of  the  mould ;  if  every  print  were  filled  with  a  core  such 
as  Fig.  165,  made  in  an  appropriate  core-box,  the  matter  would  be 
accomplished  with  great  facility  and  truth. 

The  iron-founder  makes  frequent  use  of  flasks,  which  divide  in 
three  or  four  parts ;  this  is  done  in  many  cases  simply  to  increase 
the  depth  of  the  contained  space ;  in  which  case  when  wooden  flasks 
were  employed,  they  admitted  of  being  temporarily  fixed  together 
by  dogs,  or  large  iron  staples,  driven  a  little  way  into  the  neighbor- 
ing flasks,  but  the  modern  iron  flasks  are  fixed  by  cotters.  The 
following  examples  will  show  the  nature  of  some  other  uses  to 
which  the  flasks  with  several  partings  are  applied. 


Fig.  166. 


Fig.  167. 


I 


-C 
..2 
...B 
..  1 
—  A 


A  casting,  such  as  Fig.  166,  which  represents  the  top  of  a  sliding- 
rest  for  a  lathe,  might  be  moulded  in  a  very  deep  two-part  flask,  if 
the  parting  were  made  upon  the  dotted  line  a,  a ;  but  there  would 
be  very^ great  risk  of  tearing  down  the  mould  in  drawing  out  the 
pattern,  and  from  the  depth,  there  would  be  scarcely  a  possibility 
of  repairing  it,  and  the  metal  would  probably  be  strained.  It  would 


CASTING   AND   FOUNDING. 


259 


be  also  possible  to  mould  it  with  the  joining  upon  the  line  5,  pro- 
vided several  cores  were  employed,  but  the  mode  adopted  is  more 
convenient  than  either  of  these — when  the  pattern  is  made  in  two 
parts,  and  the  flask  in  three,  as  in  Fig.  167. 

A  and  B  are  first  united  and  partly  filled  with  sand,  the  pattern 
is  knocked  in  as  represented,  and  the  whole  well  rammed,  especi- 
ally in  the  groove,  the  parting  being  made  on  the  line,  1,  1,  and 
dusted.  C  is  now  put  on,  filled,  and  struck  off  level,  a  board  is 
put  above  it,  and  ABC  are  all  turned  over  together,  A  becoming 
the  top. 

A  is  now  removed,  and  the  sand  is  cut  away  to  make  the  second 
parting  on  the  line  2,  2,  after  which  A  is  replaced,  and  the  run- 
ner-stick is  inserted  to  make  the  runner,  r.  On  removing  the  pat- 
tern, the  runner-stick  r  is  first  taken  out,  A,  or  the  top  part  of  the 
flask,  is  lifted  off)  and  the  white  part  of  the  pattern  is  drawn  out ; 
B,  or  the  middle  part,  is  then  lifted,  and  the  last  or  shaded  piece 
of  the  pattern,  is  drawn  out  of  the  mould,  which  is  now  put  to- 
gether again,  and  poured  through  r ;  so  that  the  top  surface  of  the 
pattern,  as  seen  in  both  views,  becomes  the  face,  from  being  cast 
downwards,  or  upon  the  lowest  piece  C,  of  the  flask,  called  the 
drag. 

The  part  c,  Fig.  166,  might  be  cast  with  a  chamfer  in  three  dif- 
ferent ways ;  although,  in  small  castings,  it  is  more  usual  to  cast  it 
square  and  plane  it  out  of  the  solid.  First,  the  pattern  might  be 
moulded  square,  and  the  top  A,  after  removal,  might  be  worked  to 
the  angle  by  aid  of  the  trowel  and  a  chamfered  slip  of  wood,  used 
as  a  gage ;  or  secondly,  by  the  employment  of  a  core,  the  print  of 
which  is  represented  by  the  dotted  lines  terminating  at  the  angle  d, 
Fig.  166  ;  or  thirdly,  by  having  a  loose  slip  on  the  pattern  sliding 
on  the  line  c,  Fig.  166,  so  as  to  be  drawn  off  when  the  top  A,  had 
been  lifted.  This  last  method  is  analogous. to  that  represented  in 
Fig.  168,  also  intended  for  a  sliding- rest  •  and  which  might  be  cast 


Fig.  168. 


Fg.  169. 


in  a  two  part  flask,  if  the  two  camfers  c  c,  were  fitted  loosely  upon 
slides  as  shown ;  but  a  three-part  flask  is  more  convenient,  as  ex- 
plained by  Fig.  169,  in  which  the  pattern  is  inverted. 


260  THE    PRACTICAL    METAL-WORKER'S    ASSISTANT. 

The  lowest  piece""C,  or  the  drag,  is  parted  upon  the  line  1,  1,  but 
its  sand  extends  upwards  between  the  two  sides  of  the  pattern,  as 
shown  by  the  shade-lines.  The  middle  piece  B,  is  parted  through 
the  line  2  2 ;  and  lastly  A.  the  top,  is  filled  up  level,  the  runner- 
stick  at  r  being  inserted  at  the  time,  A  is  first  lifted,  and  all  the 
pattern  is  then  removed,  excepting  the  chamfered  bars  and  their 
slides,  which  are  represented  black  ;  this  pattern  delivers  its  own 
cores  for  the  circular  mortises  m  m,  the  sand  forming  them  being 
a  part  of  that  in  B,  or  the  middle  flask ;  lastly,  B  is  lifted,  and 
chamfer-slips  are  picked  off  from  C.  This  pattern  may  conse- 
quently be  moulded  without  turning  over  the  flask,  and  every  part 
of  the  mould  is  quite  accessible  for  repair. 

The  pedestal  of  the  swage-block,  Fig.  95,  -page  141,  is  another 
good  example  of  moulding  in  a  three-part  flask.  The  model  is 
made  with  the  upper  fillet  loose,  also  with  the  sides  solid,  or  with- 
out the  holes,  and  the  object  is  moulded  as  it  stands.  The  top  part 
of  the  flask  opens  at  the  upper  moulding,  and  which  latter  is  then 
removed  from  the  pattern ;  the  middle  flask  divides  at  the  plinth 
or  flange,  so  that  when  this  has  been  lifted,  the  pattern  also  may 
be  withdrawn,  leaving  a  square  pedestal  of  sand,  as  large  as  the 
interior  of  the  model,  standing  upon  the  bottom  part  or  drag,  as  in 
169.  The  panels  are  made  by  means  of  a  core-box  of  the  kind 
Fig.  146,  p.  246,  the  box  is  exactly  as  thick  as  the  metal  to  be 
cast ;  and  the  circular  cores  are  then  fixed  upon  the  pedestal  of 
sand  by  means  of  a  few  wires  or  nails,  after  which  the  flask  is  puj; 
together,  ready  for  pouring. 

If  the  Fig.  95,  here  referred  to,  had  four  fluted  columns  at  the 
four  angles,  either  with  a  large  cap  to  each,  or  with  a  square  entab- 
lature connecting  the  whole  of  them,  the  object  might  be  also  cast 
in  one  piece,  if  moulded  in  a  three-part  flask.  After  removing  the 
top  flask,  the  entablature  and  capitals  would  be  first  withdrawn,  the 
columns  being  divided  through  their  smallest  diameters ;  the  mould 
would  be  then  turned  over,  and  upon  lifting  off  the  drag,  or  bot- 
tom-piece, the  remainder  of  the  pattern  could  be  drawn,  either  in 
one  single  piece,  or  if  the  pillars  were  loose,  the  five  parts  could  be 
more  safely  extracted ;  the  three-part  mould  would  be  put  together 
again  and  reversed  for  pouring.  In  this  general  maimer,  by  mak- 
ing either  the  mould,  or  the  pattern,  or  both,  in  different  pieces, 
and  by  the  judicious  employment  of  cores  and  drawbacks,  objects 
apparently  the  most  untractable  are  cast  with  very  great  perfection. 

The  iron-founders  are  likewise  very  dexterous  in  making  cast- 
ings in  some  respects  different  from  the  patterns  from  which  they 
are  moulded ;  thus,  if  the  pattern  be  too  long,  or  that  it  be  tem- 
porarily desired  to  obliterate  some  few  parts,  the  mould  is  made  of 
the  full  size  and  stopped-off,  additional  sand  being  worked  into  the 
mould  by  aid  of  the  trowel  and  some  temporary  piece  of  wood  to 
represent  the  imagined  termination  of  the  pattern.  On  the  other 
hand,  any  simple  enlargement  or  addition  is  not  always  added  to 


CASTING   AND   FOUNDING.  261 

the  pattern,  but  it  is  frequently  cut  out  of  the  mould  with  the 
trowel,  in  a  similar  manner. 

Many  common  works,  such  as  plates,  gratings,  parts  of  ordinary 
stoves,  and  simple  objects,  are  made  to  iwitten  measures,  and  with- 
out patterns,  as  a  few  parallel  slips  of  wood  to  represent  the  margin 
of  the  casting,  are  arranged  for  the  purpose  upon  a  flat  body  of 
sand,  which  is  modelled  up  almost  entirely  by  hand;  but  for  all 
accurate  purposes  and  for  machinery,  good  and  well-made  patterns 
are  indispensable,  and  to  some  particulars  of  which  a  little  atten- 
tion will  be  now  devoted. 

REMARKS  ON  PATTERNS  FOR  IRON  CASTINGS. — The  construc- 
tion of  patterns  for  iron  castings  requires  not  only  the  observance 
of  all  the  particulars  conveyed  on  pages  238  to  240,  but,  in  ad- 
dition, the  large  size  of  the  models,  the  peculiar  methods  employed 
in  moulding  them,  and  the  nearly  inflexible  nature  of  the  iron  cast- 
ings when  produced,  call  for  some  other  and  important  considera- 
tions,— and  which  should  not  be  entirely  overlooked,  even  in  works 
of  comparatively  small  size,  or  it  may  lead  to  failure  and  disap- 
pointment. 

Thus,  it  becomes  necessary  to  make  patterns  in  some  degree 
larger  than  the  intended  iron  castings,  to  allow  for  their  contraction 
in  cooling,  which  equals  from  about  the  ninety-fifth  to  the  ninety- 
eighth  part  of  their  length,  or  nearly  one  per  cent.  This  allowance 
is  very  easily  and  correctly  managed  by  the  employment  of  a  con- 
traction rule,  which  is  made  like  a  surveyor's  rod,  but  one-eighth 
of  an  inch  longer  in  every  foot  than  ordinary  standard  measure. 
By  the  employment  of  such  contraction  rules,  every  measurement 
of  the  pattern  is  made  proportionally  larger  without  any  trouble 
of  calculation. 

When  a  wood  pattern  is  made,  from  which  an  iron  pattern  is  to 
be  cast,  the  latter  being  intended  to  serve  as  the  permanent  foundry 
pattern,  as  there  are  two  shrinkages  to  allow  for,  a  double  contrac- 
tion rule  is  employed,  or  one  the  length  of  which  is  one-quarter  of 
an  inch  in  excess  of  every  foot.  These  rules  are  particularly  im- 
portant in  setting  out  alterations  in,  or  additions  to,  existing  ma- 
chinery. The  latter  is  measured  with  the  common  rule,  and  the 
new  patterns  are  set  out,  to  the  same  nominal  measures,  with  a 
single  or  double  contraction  rule,  as  the  case  may  be,  the  three 
being  made  in  some  respects  dissimilar  to  avoid  confusion  in  their 
use.  The  entire  neglect  of  contraction  rules  incurs  additional 
trouble  and  uncertainty.  The  contraction  of  brass  is  nearly  three- 
sixteenths  of  an  inch  in  every  foot,  but  from  the  small  size  of 
brass  castings  the  contraction  rule  is  less  required  for  them,  as  the 
differences  may  be  easily  allowed  for  without  it. 

Iron  castings  weigh  about  fourteen  times  as  much  as  the  ordi- 
nary deal  and  fir  patterns  from  which  they  are  made,  that  being 
nearly  the  ratio  of  the  specific  gravities  of  those  materials. 

Patterns  for  iron  castings  are  much  more  frequently  divided  into 
several  parts  than  those  for  brass.  For  instance,  the  division  into 


262  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

two  equal  parts,  after  the  manner  of  Fig.  153,  p.  248  (but  without 
reference  to  the  under-cutting)  is  very  common,  as  both  the  pattern 
and  flask  separate  when  the  top  part  is  lifted,  and  the  halves  of  the 
pattern  can  then  be  drawn  out  from  the  halves  of  the  flask  with 
much  less  risk  of  tearing  down  the  sand. 

Referring  to  p.  232,  Fig.  122  if  small,  would  be  moulded  as  rep- 
resented, with  false  cores  or  drawbacks;  but  if  it  were  a  large 
fluted  column,  the  iron-founder  would  employ  a  solid  two-part 
flask  ;  the  shaded  parts  would  together  represent  the  body  of  sand 
in  the  drag,  and  the  pattern  would  be  made  in  three  parts  some- 
thing like  a  boot-tree.  When  the  top  flask  had  been  lifted,  the 
central  slice  of  the  pattern,  extending  from  the  two  upper  to  the 
two  lower  angles,  would  be  withdrawn  vertically,  and  the  two  outer 
pieces  would  be  released  sideways.  The  general  rule  is  to  divide 
the  circumference  of  the  pattern  into  six  equal  parts,  and  to  let  the 
central  slice  equal  one  of  them  in  width. 

The  Figs.  167  and  169,  representing  two  parts  of  a  slide-rest, 
and  the  pedestal,  95,  are  some  amongst  many  of  the  common  ex- 
amples of  the  division  of  the  patterns ;  and  with  which  may  be 
associated,  the  numerous  subdivisions  of  the  mould  instead  of  the 
pattern  by  the  employment  of  cores,  many  applications  of  which 
have  been  also  explained.  All  these  matters  display  much  in- 
teresting and  ingenious  contrivance,  resorted  to  either  to  render  pos- 
sible the  operation  of  moulding,  or  to  facilitate  its  performance. 

To  lessen  the  distortion  of  castings  from  their  unequal  contrac- 
tion in  cooling,  it  is  important  that  the  models  should  be  nearly 
symmetrical.  For  example,  bars  or  rods  of  all  the  sections  in 
Fig.  121,  p.  232,  may  be  expected  to  remain  straight ;  perhaps  g 
is  the  most  uncertain,  but  if  the  lower  fins  of  e  and  h  were  removed, 
their  flat  surfaces,  then  exposed  to  the  sand,  would  become  round- 
ing or  convex  in  length,  from  the  contraction  of  the  upper  rib 
being  unopposed  by  that  of  a  similar  piece  on  the  under  side. 
Bars  and  beams,  the  sections  of  which  resemble  the  letter  I,  are  of 
the  most  favorable  kind  for  general  permanence,  and  also  for 
strength,  and  large  panels  may  be  cut  out  from  their  central  plates 
to  diminish  their  weight  without  materially  reducing  their  stability. 
They  are  much  used,  not  only  in  building,  but  also  in  the  framing 
of  machinery,  wMch  is  in  a  great  measure  based  upon  the  same 
general  rules. 

^  It  is  also  of  great  importance,  especially  in  castings  of  large 
size,  that  the  thickness  of  the  metal  should  be  nearly  alike  through- 
put, so  that  it  may  cool  at  all  parts  in  about  the  same  time.  Should 
it  happen  that  one  part  is  set  or  rigid,  whilst  another  is  semi-fluid 
or  in  the  act  of  crystallizing,  there  is  great  risk  of  the  one  part 
being  altogether  torn  from  the  other  and  producing  fracture.  Or 
should  the  disturbing  force  be  insufficient  to  break  the  casting,  it 
may  strain  the  metal  nearly  to  its  limit  of  tenacity  or  elasticity ; 
so  that  a  force  far  below  that  which  the  casting  should  properly 
bear  may  break  it  in  pieces. 


CASTING   AND  FOUNDING.  263 

An  example  of  this  is  seen  in  wheels  with  very  light  arms  and 
heavy  rims  or  bosses.  The  arms  sometimes  cool  so  quickly  as  to 
tear  themselves  away  from  the  still  hot  rim  or  nave  ;  or  when  the 
arms  are  solidified  without  fracture,  the  contraction  of  the  rim  mav 
so  compress  the  spokes  endways  as  to  dish  the  wheel  (in  the  man- 
ner of  an  ordinary  carriage  wheel),  and  thereby  strain  the  casting 
nearly  or  quite  to  the  point  of  fracture.  The  arms  are  sometimes 
curved  like  the  letter  S,  instead  of  being  straight  and  radial ;  the 
contraction  then  increases  their  curvature  with  less  risk  of  accident 
than  to  straight  arms.  It  appears  to  be  often  desirable  to  super- 
sede the  straight  diagonal  braces  of  iron  castings  by  curved  lines, 
which  are  both  more  ornamental  and  better  disposed  to  yield 
to  compression  or  extension  by  a  slight  alteration  in  their  cur- 
vature. 

A  more  elegant  way  of  avoiding  the  mischief  is  by  placing  the 
spokes  as  tangents  to  the  central  boss,  in  which  case  the  contraction 
of  the  rim  makes  a  small  angular  change  of  position  in  the  boss ; 
for  the  rim,  in  thrusting  the  spokes  inwards,  causes  the  boss  to  twist 
round  a  little  way  with  far  less  risk  of  fracture. 

The  destructive  irregularity  of  thick  and  thin  works  is  parti  y 
averted  by  uncovering  the  thick  parts  of  the  casting,  or  even  cool- 
ing them  still  more  hastily,  by  throwing  on  water  from  watering- 
pots.  In  wheels  this  has  been  done  by  a  hose,  the  axis  of  which 
is  concentric  with  the  wheel,  the  arms  being  all  the  time  sur- 
rounded by  the  sand  to  retard  their  cooling ;  but  it  is  the  most 
judicious  in  all  patterns  to  make  the  substance  for  the  metal  as 
nearly  uniform  throughout  as  circumstances  will  admit,  so  as  not 
to  require  these  modes  of  partial  treatment,  which  often  compro- 
mise the  ultimate  strength  of  the  casting. 

Another  mode  sometimes  adopted  for  avoiding  the  fracture  of 
wheels,  from  the  great  dissimilarity  of  their  proportions,  is  by  in- 
serting wrought-iron  arms  in  the  mould,  but  they  do  not  always 
unite  kindly  with  the  iron  of  the  rim  and  the  nave.  The  same  in- 
convenience occurs  when  iron  pins  are  inserted  in  the  ends  of 
either  iron  or  brass  castings,  to  serve  for  their  attachment  to  their 
respective  places.  In  iron  castings  it  frequently  produces  the  eft'ect 
of  chill  casting,  so  as  to  render  the  works  difficult  to  be  turned  or 
filed  at  the  junction,  and  there  is  risk  of  the  casting  becoming 
blown  or  unsound  in  either  case.  When  the  pins  are  heated  before 
being  placed  in  the  mould,  they  become  nearly  cold  before  the 
metal  can  be  poured,  and  they  also  endanger  the  presence  of  a  little 
steam  or  vapor,  which  is  detrimental;  therefore  they  are  more 
generally  put  in  cold,  notwithstanding  the  sudden  check  they  then 
give  to  the  fluid  metal. 

The  patterns  for  iron  castings  of  la^e  size  are  necessarily  very 
expensive,  especially  those  for  hollow  cylinders  and  pans,  many  of 
which  are  so  large  that  it  would  be  impossible  to  find  solid  pieces 
of  wood  from  which  the  patterns  could  be  made,  either  with 
sufficient  strength  for  present  use,  or  with  the  necessary  perma- 


264 


THE   PEACTICAL   METAL-WORKER'S   ASSISTANT. 


nence  of  form  for  a  subsequent  period,  as  they  would  be  almost, 
sure  either  to  break  or  to  become  distorted  from  the  effects  of 
unequal  shrinking.  Such  patterns,  therefore,  require  to  be  made 
of  a  great  many  thin  layers  or  rings  of  wood,  each  consisting  of 
6,  8,  or  12  pieces,  like  the  felloes  of  wheels,  so  that  in  all  parts  the 
grain  may  be  nearly  in  the  direction  of  a  tangent. 

As  they  are  glued  up,  every  succeeding  layer  is  connected  with 
the  former  by  glue  and  wooden  pins  or  dowels,  and  the  whole  is 
afterwards  turned  to  the  tubular  or  hemispherical  form,  as  the  case 
may  be.  As  the  castings  are  generally  required  to  be  rather  thin, 
such  models  are  not  only  very  expensive,  but  also  very  liable  to 
accident ;  and  besides,  it  frequently  occurs  that  only  one  or  two 
castings  of  a  kind  may  be  required,  which  makes  the  proportional 
cost  of  the  patterns  excessive. 

It  fortunately  happens,  however,  that  this  case,  which  is  one  of 
the  most  costly  and  uncertain,  by  the  employment  of  ordinary 
wood  or  metal  patterns,  becomes  exceedingly  manageable  by  a 
peculiar  and  simple  application  of  the  art  of  turning  (the  one  great 
centre  of  the  constructive  arts,  to  which  these  pages  are  intended 
immediately  and  collaterally  to  apply) ;  and  by  which  process,  or 
one  branch  of  bam  moulding,  to  be  explained  hereafter,  patterns 
are  not  generally  required. 

LOAM  MOULDING.— Figs.  170,  171,  and  172,  are  intended  to 
illustrate  this  process  as  regards  a  steam  cylinder.  Fig.  170  is  the 


Figs.  170 


171 


172. 


entire  section  of  the  mould  in  its  first  stage.  Figs.  171  and  172 
are  the  half  sections  of  the  second  and  third  stages,  preparatory  to 
burying  the  mould  in  the  pit  in  which  it  is  to  be  filled. 

The  inner  part  of  the  loam  mould  is  called  the  core  when  small, 
but  the  nowel  when  large ;  the  outer  is  called  the  case  or  the  cope. 
Each  part  is  built  upon  an  iron  loam-plate,  or  a  ring  cast  rough  on 
the  face,  and  with  four  ears  by  which  it  may  be  lifted.  The  mould 
is  occasionally  erected  upon  four  shallow  pedestals  of  bricks  for 
the  convenience  of  making  a  fire  beneath  it  to  dry  the  loam.  At 


CASTING  AND   FOUNDING.  265 

other  times  it  ^  made  upon  a  low  truck,  upon  which  it  may  be 
wheeled  into  the  loam  stove,  which  is  heated  to  about  the  tempera- 
ture of  300  to  400  degrees  Fahrenheit. 

A  vertical  axis  a,  is  mounted  in  any  convenient  manner,  fre- 
quently in  two  holes  in  the  truck  itself,  or  as  shown  in  the  figure, 
in  a  pedestal  or  socket  erected  upon  the  truck ;  at  the  other  times 
the  axis  is  mounted  in  a  hole  in  the  loam-plate,  and  in  any  bear- 
ing attached  either  "to  the  building  or  its  roof. 

The  first  step  is  to  fix  upon  the  spindle,  the  templet  b  b,  at  the 
distance  of  the  radius  of  the  cylinder,  either  by  one  or  two  clutcJies 
with  various  binding  screws.  An  inner  cylinder  of  brickwork  is 
then  built  up,  plastered  by  the  hands  with  soft  loam  (which  is  re- 
presented black  in  all  figures),  and  scraped  into  the  cylindrical 
form  by  the  radius  board,  which  is  moved  round  on  its  axis  by  a 
boy.  When  the  surface  is  smooth  and  fair  it  is  thoroughly  dried, 
after  which  it  is  brushed  over  with  blackwash,  and  again  dried. 
The  charcoal  dust  in  the  blackwash  serves  as  a  parting,  to  prevent 
the  succeeding  portions  of  the  loam-mould  from  adhering  to  the 
first. 

The  templet  c  c,  Fig.  171,  cut  exactly  to  the  external  form  of  the 
cylinder,  is  now  attached  to  the  axis  at  the  distance  from  the  core 
required  for  the  thickness  of  the  metal :  some  additional  loam  is 
.thrown  on  to  form  the  thickness,  which  is  smoothed  in  the  same 
careful  manner  as  the  centre,  after  which  the  templet  and  spindle 
are  dismounted,  and  the  thickness,  which  is  represented  white  in 
Figs.  171  and  172,  is  also  dried  and  blackwashed. 

The  ring  for  the  outer  case  or  cope  is  now  laid  down,  and  its 
position  is  denoted  either  by  fixed  studs  or  by  marks ;  and  the 
outer  case  represented  in  Fig.  172  is  built  up  of  bricks  and  loam, 
with  an  inner  facing  of  loam  worked  very  accurately  to  the  turned 
thickness.  The  new  work  or  the  cope,  is  also  thoroughly  dried, 
and  afterwards  lifted  off  very  carefully  by  means  of  the  crane  and 
a  cross  beam  with  four  chains.  This  process  likewise  drags  off 
the  thickness,  which  usually  breaks  in  the  removal ;  its  remains 
are  carefully  picked  out  of  the  cope,  both  parts  of  the  mould  are 
repaired,  and  again  blackwashed  and  dried. 

When  the  cylinder  requires  ports  at  the  ends,  or  the  short  tubes 
with  flanges  for  attaching  the  steam-passages,  models  of  the  tubes 
are  worked  into  the  cope,  and  are  afterwards  withdrawn ;  the  cores 
are  made  in  core  boxes,  and  are  partly  supported  by  the  outer  ex- 
tremity, and  partly  upon  grains,  or  two  little  plates  of  sheet  iron 
connected  by  a  central  wire,  the  whole  being  equal  to  the  thick- 
ness of  the  metal  at  the  part.  When  steam-passages  are  wanted, 
either  along  the  side,  or  around  the  cylinder,  they  are  worked  up 
in  clay  upon  the  thickness,  and  duly  covered  in  by  the  cope ;  their 
cores 'are  supported,  partly  by  their  loose  ends,  and  partly  by 
grains,  which  become  entirely  surrounded  by,  and  fixed  in  the 
metal,  when  it  is  poured. 

There  is  always  some  uncertainty  of  the  sound  union  of  the 


266  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

grains,  or  other  pieces  of  iron,  with  the  cast-me^al.  Some  cast 
them  in  iron  and  file  them  quite  bright,  others  also  tin  them,  ap- 
parently to  preserve  them  from  rust,  as  the  tin  must  be  instantly 
dissipated  by  the  hot  metal.  Grains  should  always  present  clean 
metallic  surfaces,  and  when  used  for  very  thin  castings  to  prevent 
them  from  dropping  out,  the  wires  are  nicked  with  a  file  that  they 
may  be  keyed  in  the  metal.  It  is  however  better  to  avoid  the  use 
of  grains,  which  may  be  generally  done  by  giving  the  core  sand 
bearings,  and  afterwards  plugging  up  the  holes  in  the  casting. 

The  mould  is  now  put  together  in  a  pit  sunk  in  the  floor  of  the 
foundry,  and  the  two  iron  plates  are  screwed  together ;  the  surround- 
ing space  being  rammed  hard  to  prevent  tlie  mould  from  bursting 
open,  but  the  inner  part  is  left  much  more  loose  for  the  escape  of 
the  air.  The  top  edges  of  the  mould  are  covered  over  with  a  loam- 
cake  (which  has  been  previously  made  and  dried),  or  a  ring  three 
or  four  inches  thick,  strengthened  with  iron  bars  amidst  the  clay, 
the  joining  being  made  air-tight  by  a  little  cows'  hair,  and  by  the 
pressure  of  a  quantity  of  iron  weights ;  the  loam-cake  is  generally 
perforated  with  many  holes  as  shown  at  d,  for  the  entry  of  the 
metal  and  the  escape  of  the  air.  But  provision  must  always  be 
made  in  casting  thin  cylinders,  boxes,  and  such  like  forms,  for  the 
breaking  up  of  the  core  as  soon  as  the  metal  is  set,  to  prevent  the 
metal  scoring  or  rending  from  its  contraction  upon  a  rigid  unyield- 
ing' centre. 

To  enable  the  mould  to  resist  the  great  pressure  of  the  lofty 
column  of  fluid  metal  (equal  at  the  base  to  near  60  pounds  on 
every  square  inch),  the  core  is  strengthened  by  diametrical  iron 
bars  entering  slightly  into  the  brickwork :  the  outer  cylinder  is 
surrounded  at  a  small  distance  by  iron  rings  piled  one  on  the 
other,  the  interval  being  rammed  with  sand  ;  and  stays  are  placed 
in  all  directions  from  the  rings  to  the  sides  of  the  pit,  which  is 
either  lined  with  brick-work,  or  when  liable  to  be  inundated  with 
water,  it  is  made  of  iron,  like  a  water-tight  caisson. 

Small  cylinders  are  moulded  in  sand  from  wooden  models,  and 
only  the  cores  are  turned  in  loam ;  for  cylinders  of  the  smallest 
size  the  cores  are  made  of  sand  in  core  boxes  as  already  explained. 

Large  pans,  and  various  other  circular  works,  are  moulded  pre- 
cisely in  the  same  way  as  cylinders ;  except  that  curved  templets 
are  used,  and  that  towards  the  conclusion"  the  apertures  through 
which  the  spindle  passed  are  filled  in  and  worked  by  hand  to  the 
general  surface. 

Water-pipes  are  made  much  in  the  same  mode,  but  the  cores  for 
these  are  turned  upon  an  iron  tube  pierced  full  of  holes,  which  is 
laid  horizontally  across  two  iron  trestles  with  notches,  and  is  kept 
in  rotation  by  a  winch  handle  at  the  end :  there  is  also  a  shaper- 
board  or  scraper  fixed  parallel  with  the  axis;  this  primitive 
apparatus  is  called  a  founder's  lathe. 

The  perforated  tube  (serving  as  the  mandrel)  is  first  wound 
round  with  hay-bands,  then  covered  with  loam,  and  the  core  is 


CASTING  AND   FOUNDING.  267 

turned,  dried  ancl,  blackwashed ;  the  thickness  is  now  laid  on  and 
also  blackwashed,  after  which  the  object  is  moulded  in  sand.  The 
thickness  is  next  removed  from  the  core,  which  latter  is  inserted 
in  the  mould,  and  supported  therein  by  the  two  prints  at  the  extrem- 
ities, and  by  grains  with  long  wires,  the  positions  of  which  may 
be  seen  by  the  little  bosses  on  the  pipe,  the  metal  being  there 
made  purposely  thicker  to  avoid  any  accidental  leakage  at  those 
parts,.  When  pipes  are  cast  in  large  quantities,  they  are  moulded 
from  wooden  patterns  in  halves,  so  that  it  only  becomes  necessary 
to  turn  the  core,  and  this,  .when  made  in  the  above  manner,  is 
sufficiently  porous  for  the  escape  of  the  air. 

The  moulds  for  crooked  pipes  and  branches  are  frequently  made 
in  halves,  upon  a  flat  iron  plate.  An  iron  bar  or  templet  of  the 
curve  required  is  fixed  down,  and  a  semicircular  piece  of  wood, 
called  a  strickle,  is  used  for  working  and  smoothing  the  half  core ; 
next  a  larger  strickle  is  used  for  laying  on  the  thickness,  the  two 
halves  are  then  fixed  together  by  wires,  and  moulded  from  in  the 
sand  flask ;  the  thickness  is  now  stripped  off  the  core,  which  is  fixed 
in  the  mould  by  its  extremities,  and  if  needful,  is  supported  also 
upon  grains. 

By  the  employment  of  these  means,  although  the  loam  work  re- 
quires time  for  the  drying,  yet  with  ordinary  care  an  equality  of 
thickness  may  be  maintained,  notwithstanding  the  complexity  of 
the  outline,  and  without  the  necessity  for  wooden  patterns. 

Very  many  of  the  large  works  in  brass  are  also  moulded  in  loam, 
the  management  being  in  most  respects  exactly  the  same  as  for 
iron,  except  that  in  some  ornamental  works  wax  is  more  or  less 
employed,  and  is  melted  out  of  the  moulds  before  the  entry  of  the 
metal ;  a  very  slight  view  of  the  methods  will  serve  as  a  sequel  to 
the  subject  of  brass  founding. 

Large  bells  are  turned  in  almost  the  same  manner  as  iron  cylin- 
ders or  pans,  by  means  of  wooden  templets,  edged  with  metal  and 
shaped  to  the  inner  and  outer  contour  of  the  core  and  thickness. 
The  inscription  and  ornaments  are  either  impressed  within  the  cope, 
the  clay  of  which  is  partially  softened  for  the  purpose,  or  the  orna- 
ments are  moulded  in  wax,  and  fixed  on  the  clay  thickness  before 
making  the  cope.  Less  generally  the  whole  exterior  face  of  the 
bell,  or  indeed  its  entire  substance,  is  modelled  in  wax,  and  melted 
out  before  pouring.  In  any  case,  the  concluding  steps  in  filling  up 
the  apertures  where  the  spindle  passed,  are  to  attach  a  dissected 
wooden  pattern  of  the  central  stem  and  of  the  six  cannons  or  ears 
by  which  the  bell  is  slung,  which  parts  are  moulded  in  soft  loam ; 
and  then,  the  parts  having  been  dried  and  replaced,  and  the  iron 
ring  for  the  clapper  inserted,  the  whole  is  ready  for  the  pouring 
pit.  The  heaviest  bells  are  moulded  within  the  pit  the  same  as 
huge  cylinders.  • 

Brass  guns  are  also  moulded  in  loam,  and  in  a  somewhat  peculiar 
manner ;  a  taper  rod  of  wood  much  longer  than  the  gun,  is  wound 
round  with  a  peculiar  kind  of  soft  rope,  upon  which  the  loam  is  put 


268  THE  PEACTICAL   METAL-WOEKEE'S  ASSISTANT. 

for  making  the  rough  casting  model  of  the  gun,  which  is  turned  to 
a  templet ;  the  work  is  executed  over  a  long  fire  to  dry  it  as  it 
proceeds,  and  the  model  is  made  about  one-third  longer  than  the 
gun  itself.  The  model  when  dried  and  blackwashed  all  over,  is 
covered  with  a  shell  of  loam,  not  less  than  three  inches  thick,  secured 
by  iron  bands,  the  shell  is  also  carefully  dried ;  after  this  the  taper 
bar  is  cautiously  driven  out  from  its  small  end,  the  coil  of  rope  is 
pulled  out,  and  so  likewise  is  every  piece  of  the  clay  model  of  the 
gun. 

The  parts  for  the  cascable  and  trunnions,  which  should  have 
been  worked  separately  upon  appropriate  wooden  models,  Hre  then 
attached  to  the  shell.  Should  the  gun  have  dolphins,  or  any  other 
ornamental  figures,  now  seldom  the  case,  they  are  modeled  in  wax 
and  fixed  on  the  clay  model  before  the  shell  is  formed,  and  are  then 
melted  out  to  make  the  required  space  for  the  metal. 

"When  all  is  ready  and  dried,  six,  eight,  or  more  of  these  loam 
cases,  or  shells,  are  sunk  perpendicularly  in  a  pit  at  the  mouth  of 
the  reverberatory  furnace,  and  the  earth  is  carefully  rammed  around 
them ;  at  the  same  time  a  vertical  runner  is  made  to  every  mould, 
to  enter  either  at  the  bottom,  or  not  higher  than  the  trunnion :  the 
upper  ends  of  the  runners  terminate  in  the  bottom  of  a  long  trough 
or  gutter,  at  the  far  end  of  which  is  a  square  hole,  to  receive  the 
excess  of  metal. 

In  casting  brass  guns,  tapping  the  furnace  is  rather  a  ceremony, 
and  certainly  an  imposing  sight :  the  middle  and  the  end  of  the 
trough,  are  each  stopped  by  a  shovel  or  gate  held  across  the  same ; 
and  the  runners  are  all  stopped  by  long  iron  rods,  held  by  as  many 
men.  When  all  is  pronounced  to  be  ready,  the  stopper  of  the  fur- 
nace is  driven  inwards  with  a  long  heavy  bar  swung  horizontally 
by  two  or  three  men,  and  the  metal  quickly  fills  the  trough ;  on 
the  word  of  command,  "  number  one,  draw,"  the  metal  flows  into  the 
first  mould,  and  fills  it  quickly  but  quietly  from  the  bottom ;  the 
mould  being  open  at  the  top,  no  air  can  be  accidentally  enclosed. 
Numbers  two,  three,  and  four  are  successively  ordered  to  draw. 
The  first  shovel  is  then  removed  from  the  great  channel,  and  now 
the  guns,  five  to  eight  or  ten,  as  the  case  may  be,  are  similarly 
poured  and  filled  to  the  level  of  the  trough ;  after  which  the  last 
shovel  is  withdrawn,  and  the  residue  of  the  metal  is  allowed  to  run 
into  the  square  bed  or  pit  prepared  for  it.  The  flow  of  metal  from 
the  furnace  is  regulated  by  the  tapping  bar,  the  end  of  which  is 
taper,  and  is  thrust  more  or  less  into  the  mouth  of  the  furnace  as 
required  ;  the  trough  and  runners  are  thus  kept  exactly  full,  which 
is  an  important  point  in  most  cases  of  pouring,  as  it  prevents  a 
current  of  air  being  carried  down  along  with  the  metal. 

Large  bells  are  poured  much  in  the  same  manner,  except  that 
the  runners  are  at  the  top,  and  the  metal  runs  from  the  great- 
channel,  through  smaller  gutters  to  every  sunk  mould,  the  stoppers 
for  which  are  successively  drawn.  For  quantities  of  brass  inter- 
mediate between  the  charge  of  an  ordinary  crucible,  and  such  as 


CASTING  AND  FOUNDING.  269 

require  the  reverberatory  furnace,  the  large  ladles  or  shanks  of  the 
iron-founder  are  used ;  the  contents  of  four  or  six  crucibles  being 
poured  into  the  shank  as  quickly  as  possible,  and  thence  in  one 
stream  into  the  mould. 

The  author  of  the  article  Founding,  in  the  Encyclopedia  Metropo- 
litana,  minutely  describes  three  ways  of  casting  large  hollow  statues, 
which  are  briefly  as  follows : 

First :  a  rough  model  of  the  figure  is  made  in  clay,  but  somewhat 
smaller  than  its  intended  size ;  it  is  covered  over  with  wax,  which 
is  modeled  to  the  required  form,  or  the  wax  is  worked  up  in  sep- 
arate pieces  and  afterwards  attached :  various  rods  or  cylinders  of 
wax  to  make  the  apertures  for  the  runners  or  air  holes,  are  fixed 
about  the  figure  and  led  upwards.  The  whole  is  now  surrounded 
with  a  coating  of  loam  and  similar  materials,  the  inner  portion  of 
which  is  ground  very  fine  and  laid  on  with  a  brush  like  paint ; 
and  the  outer  part  is  secured  with  iron  bands.  When  all  has  been 
partially  dried  a  fire  is  lighted  beneath  the  grating  on  which  the 
figure  is  built,  to  cause  the  wax  to  run  out  through  one  or  more 
apertures  at  the  base,  which  are  afterwards  stopped,  and  all  is 
thoroughly  dried  and  secured  in  the  pit,  after  which  the  charge  of 
the  furnace  is  let  into  the  cavity  left  by  the  wax. 

Secondly :  the  finished  figure  is  modeled  in  clay,  and  stuck  full 
of  brass  pins  just  flush  with  its  surface,  which  surface  is  now  scraped 
away  as  much  as  the  thickness  required  in  the  metal ;  the  reduced 
figure  is  now  covered  with  wax  mixed  with  pitch  or  rosin,  which 
is  worked  to  the  original  size  with  all  the  exactness  possible.  The 
other  stages  are  the  same  as  in  the  foregoing ;  the  metal  studs  or 
pins  prevent  the  mould  and  core  from  falling  together,  and  ttey 
afterwards  melt,  becoming  a  part  of  the  metal  constituting  the 
figure. 

Thirdly :  the  finished  figure  is  modeled  in  plaster,  and  a  piece- 
mould  is  made  around  it,  the  blocks  of  which  consist  internally  of 
a  layer  of  sand  and  loam  1£  inch  thick,  and  externally  of  plaster 
one  foot  thick.  The  mould  when  completed  is  taken  to  pieces, 
dried,  and  rebuilt  in  the  casting  pit ;  it  is  now  poured  full  of  a 
composition  suitable  for  the  core,  the  mould  is  again  taken  to 
pieces,  the  core  is  dried  and  scraped  to  leave  room  for  the  metal, 
and  all  is  then  put  together  for  the  last  time,  secured  in  the  pit  and 
the  statue  is  cast. 

The  first  plan  is  the  most  wasteful  of  metal,  the  third,  the  least 
so,  although  it  is  the  most  costly  when  the  time  occupied  is  also 
taken  into  account ;  but  it  has  the  advantage  of  saving  the  original 
work  of  the  artist. 

MELTING  AND  POURING  IRON.— Iron  is  usually  melted  in  a  blast 
furnace,  or  as  it  is  more  commonly  called,  a  cupola ;  although  the 
cupola  or  dome  leading  to  the  chimney,  from  which  it  would  ap- 
pear to  have  derived  its  name,  is  frequently  omitted,  the  two  or 
three  furnaces  being  often  built  side  by  side  in  the  open  foundry. 

At  the  basement  there  is  a  pedestal  of  brickwork  about  20  to  30 


270  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

inches  high,  upon  which  stands  a  cast-iron  cylinder  from  30  to  40 
inches  diameter,  and  5  to  8  feet  high;  this  is  lined  with  road-drift, 
which  contracts  its  internal  diameter  to  18  or  24  inches.  The  fur- 
nace is  open  at  the  top  for  the  escape  of  the  flame  and  gases,  and 
for  the  admission  of  the  charge,  consisting  of  pig-iron,  waste  of  old 
metal,  coke  and  lime,  in  due  proportion.  The  lime  acts  as  a  flux, 
and  much  assists  the  fusion ;  chalk  is  considered  to  answer  the  best, 
but  oyster  shells  are  very  commonly  used  where  they  are  abun- 
dant. 

At  the  back  of  the  furnace,  there  are  three  or  four  holes  one 
above  the  other  for  the  blast,  which  is  urged  by  bellows  or  by  a  re- 
volving fan.  No  crucible  is  used,  and  as  the  fluid  metal  collects  at 
the  bottom  of  the  furnace,  the  blast  pipe  is  successively  removed  to 
a  higher  hole,  and  the  lower  blast  hole  is  stopped  with  sand,  which 
partly  fuses  and  secures  the  blast  hole  very  effectually. 

The  front  aperture  of  the  furnace  through  which  the  metal  is 
allowed  to  flow  into  the  ladles  or  trough,  is  usually  made  sufficiently 
large  for  the  purpose  of  clearing  or  raking  out  rapidly  the  fuel  and 
slag,  as  the  process  is  most  laborious  owing  to  the  excessive  heat. 
This  aperture  is  closed  by  a  guard-plate,  fixed  on  by  staples  attached 
to  the  iron-case  of  the  furnace,  in  the  centre  of  which  plate  the 
tapping  hole  is  made:  during  the  time  the  metal  is  fusing  the  tap 
hole  is  closed  by  sand  well  rammed  in,  and  this  if  well  done  is  never 
found  to  fail. 

Many  iron  furnaces  are  made  octangular,  and  in  separate  parts 
bound  together  by  hoops,  so  that  in  the  event  of  the  charge  becom- 
ing accidentally  solidified  in  the  cupola,  the  latter  may  be  taken  to 
pieces  for  its  removal,  and  thus  avoid  the  necessity  of  destroying 
the  furnace.  There  is  frequently  a  light  framing  or  grating  above 
the  furnace,  upon  which  the  small  cores  are  placed  that  require  to 
be  dried. 

In  some  foundries  the  cupolas  are  built  just  outside  the  moulding 
shop,  beneath  one  or  more  chimneys  or  shafts,  which  carry  oft'  the 
fumes;  in  such  cases  the  fronts  of  the  furnaces  are  accessible  through 
an  aperture  in  the  foundry  wall,  with  which  they  are  nearly  flush ; 
when  the  furnaces  are  lofty  there  is  a  feeding  stage  at  the  back, 
from  which  the  charge  is  thrown  in. 

For  heavy  iron  castings,  which  sometimes  amount  to  thirty  tons 
and  upwards  in  one  piece,  reverberatory  or  air  furnaces  are  also 
commonly  used ;  the  ordinary  charge  for  these  is  four  to  six  tons 
of  iron,  and  five  or  six  furnaces  are  commonly  built  close  together,  so 
that  they  may  be  simultaneously  tapped  in  the  production  of  such 
enormous  works. 

For  melting  iron  in  the  small  way,  good  air  furnaces  may  be 
used,  and  also  some  of  the  black-lead  furnaces,  which  are  blown 
with  bellows,  but  this  is  one  of  the  processes  that  is  not  successful 
upon  a  limited  scale. 

Considerable  judgment  is  required  in  proportioning  the  charge 
for  the  iron  furnace,  which  always  consists  of  at  least  two,  and  often 


CASTING  AND   FOUNDING.  271 

of  half-a-dozen  kinds  of  new  pig-iron  mixed  together,  and  to  which 
new  iron  a  small  proportion  of  old  cast-iron  is  usually  added.  The 
kinds  and  qualities  used  are  greatly  influenced  by  local  and  other 
circumstances,  so  that  nothing  can  be  said  beyond  a  few  general 
remarks. 

When  the  principal  object  is  to  obtain  sound  castings  with  a  very 
smooth  face,  as  for  ornamental  works  not  afterwards  wrought,  the 
soft  kinds  of  iron  containing  most  carbon,  which  are  most  fusible 
and' flow  easily,  are  principally  used.  But  such  metal  would  neither 
possess  sufficient  hardness,  durability,  nor  strength,  for  many  of  the 
castings  employed  in  the  construction  of  edifices  and  machinery. 

If  the  cupola  contained  a  little  hard  pig-iron,  but  were  in  great 
measure  filled  with  the  old  cast-iron,  which  had  been  repeatedly 
melted  and  had  become  successively  harder  from  the  loss  of  carbon 
at  every  fusion ;  such  castings  would  be  brittle,  and  sometimes  so 
hard  as  scarcely  to  admit  of  being  cut ;  these  would  be  equally 
unfit  for  the  generality  of  machinery  from  the  opposite  causes. 

But  the  same  mixture  of  iron  will  be  found  to  differ  very  much 
according  to  the  size  of  the  objects  in  which  it  is  cast.  Iron 
which  in  a  plate  one-fourth  of  an  inch  thick  may  be  quite  brittle 
and  hard,  will  mostly  be  of  good  soft  and  useful  quality  in  a  stout 
bar  or  plate  of  two  or  three  inches  thick.  Thick  castings  are 
necessarily  slow  in  cooling,  and  are  seldom  very  hard  unless  in- 
tentionally made  so. 

Between  the  extremes  (say  three  parts  of  pig-iron  to  one  of  old, 
or  three  parts  of  old  iron  to  one  of  pig-iron),  various  qualities  may 
be  selected.  In  castings  for  machinery  the  general  aim  is  to  obtain 
a  strong,  sound,  and  tough  iron.  Mixtures  of  this  nature  which  are 
used  for  iron  ordnance  are  called  gun-metal  amongst  the  gun-founders. 

The  fireman,  or  the  individual  having  the  management  of  the 
furnace,  therefore  always  employs  the  scales  in  mingling  the  dif- 
ferent kinds  of  iron,  according  to  the  magnitude  and  character  of 
the  works  to  be  cast ;  and  until  the  sorts  in  use  are  familiarly 
known,  it  is  partly  a  matter  of  trial,  and  requires  the  same  atten- 
tion as  the  making  of  alloys,  properly  so  considered. 

It  is  much  to  be  regretted  that  no  protection  has  yet  been  found 
to  prevent  the  conversion  of  cast-iron  into  plumbago,  or  the  car- 
buret of  iron,  from  long  immersion  in  sea-water,  or  the  water  of 
copper  mines,  sewers,  and  other  places.  This,  which  is  a  most 
serious  inconvenience  in  dock  works,  sea  walls  and  mines,  arises, 
says  Dr.  Michael  Faraday,  from  the  circumstance  that  the  protoxide 
of  iron,  formed  beneath  salt  water,  is  soluble,  and  becomes  washed 
away,  thus  robbing  the  original  mass  of  its  iron ;  whereas  the 
peroxide,  or  ordinary  rust  formed  by  exposure  to  the  air,  is  in- 
soluble, and  serves  partly  as  a  defence  to  the  metal  beneath. 
When  first  raised  from  the  sea-water  the  plumbago  becomes  ex- 
ceedingly hot  from  the  action  of  the  atmosphere.  It  may  be  cut 
with  a  knife  like  an  ordinary  pencil. 

When  enough  iron  is  melted  (the  common  charge  being  two  and 


272  THE  PRACTICAL  METAL-WORKER1  S  ASSISTANT. 

a  half  to  four  cwt.,  but  sometimes  above  twelve  tons),  the  cupola  is 
tapped  in  front,  at  a  hole  close  to  the  bottom,  which  allows  the 
whole  contents  to  run  out,  either  into  ladles  or,  in  very  large  works, 
into  channels  leading  directly  to  the  moulds.  The  furnace  is  not 
unfrequently  tapped  whilst  the  charge  of  metal  is  being  melted, 
and  in  such  cases  when  the  required  quantity  has  been  removed 
into  the  ladles,  the  fireman  re-stops  the  tap-hole  by  a  conical  plug 
of  clay  on  the  end  of  a  wooden  bar.  The  process  is  called  lotting, 
and  requires  a  dexterous  hand,  or  the  whole  contents  of  the  fur- 
nace may  escape. 

In  pouring  iron,  the  means  of  conveying  the  melted  metal  to  the 
flasks  differ  with  the  quantity.  One  man  will  carry  from  fifty  to 
seventy  pounds  in  a  hand-ladle  ;  three  to  five  men  will  carry  from 
two  to  four  cwt.  in  a  double  hand-ladle,  or  a  shank ;  larger  quan- 
tities, amounting  to  sometimes  from  three  to  six  tons,  are  carried 
in  the  crane-ladle.  These  all  possess  one  feature  in  common, 
namely,  their  handles  or  pivots  are  placed  but  slightly  above  the 
centre  of  gravity  of  the  ladles, — they  may  therefore  be  tilted  very 
readily,  as  their  fluid  contents  in  obeying  the  law  of  gravitation 
are  almost  neutral  in  the  operation  of  tilting,  which  they  scarcely 
assist  or  retard,  unless  by  mismanagement  the  ladle  is  over-filled, 
and  thus  rendered  top-heavy. 

All  these  ladles  are  coated  with  a  thin  layer  of  loam,  and  every 
time  before  use  they  are  brushed  over  with  black  wash  and  care- 
fully dried.  The  hand-ladle  has  a  handle  three  or  four  feet  long, 
with  a  crutch  or  cross  piece  at  the  end,  which  is  mostly  held  in 
the  left  hand.  Frequently  the  contents  of  half-a-dozen  or  more 
hand-ladles  are  poured  simultaneously  into  the  same  flask.  The 
shank  has  a  single  handle  on  the  one  side,  and  one  made  in  two 
branches  at  the  other,  and  together  they  measure  six  to  eight  feet 
in  length.  The  tilting  is  completely  under  the  command,  of  the 
one  or  two  men  at  the  double  handle. 

The  crane-ladle  is  carried  from  the  furnace  to  the  mould  by  the 
swinging  and  traversing  motions  of  the  crane,  w^hich  is  similar  to 
those  used  at  the  iron  forges,  etc.  (see  p.  87),  and  in  very  large 
foundries  the  plan  of  the  building  is  divided  into  imaginary 
squares,  with  a  crane  in  the  centre  of  every  square,  so  that  the 
ladle  is  walked  from  one  to  the  other,  even  to  the  far  end  of  the 
shop,  with  great  facility  and  expedition. 

The  bail  or  handle  of  the  crane-ladle  is  fixed  in  its  perpendicular 
position  by  the  guard,  a  simple  bolt,  which  prevents  the  ladle  from 
being  overset  by  accident  until  it  has  reached  its  destination.  Two 
long  handles,  terminating  in  forked  branches,  are  now  fitted  by 
their  square  sockets  upon  the  swivels  or  pivots  of  the  crane-ladle, 
and  secured  by  transverse  keys, — after  which  the  guard  is  with- 
drawn ;  and  then  the  two  men  at  the  ladle,  two  others  at  the  crane, 
and  one  to  skim  the  dross  from  the  lip  of  the  ladle,  commonly 
suffice  to  manage  two  or  three  tons  and  upwards  of  fluid  iron  with 
great  ease  and  dexterity. 


CASTING  AND  FOUNDING.  273 

It  has  added  to  the  pivot  of  the  large  crane-ladle  a  tangent-screw 
and  worm-wheel,  by  which  it  may  be  gradually  tilted  by  one  man 
standing  directly  in  front  at  any  convenient  distance  ;  and  another 
man  skims  the  metal  by  a  kind  of  throttle- valve  coated  with  clay, 
which  sweeps  into  the  lip  of  the  ladle  and  keeps  back  the  sullage : 
the  axis  of  the  skimmer  is  continued  as  a  long  rod  at  right  angles 
to  the  first,  and  also  terminating  in  a  cross.  By  these  arrange- 
ments any  precise  quantity  of  metal  can  be  delivered,  and  the  risk 
of  accident  scarcely  exists. 

The  observations  offered  on  p.  252  respecting  the  temperature 
of  the  metal  suitable  to  different  brass  works,  might  be  here  in  a 
great  measure  repeated — namely,  that  the  smallest  castings  require 
very  hot  metal,  and  a  gradually  lower  temperature  is  more  suita- 
ble to  works  progressively  heavier,  to  avoid  their  becoming  sand- 
burned  or  rough  on  the  face  from  the  partial  destruction  of  the 
mould. 

When  cast-iron  is  very  hot,  the  metal  scintillates  most  beautifully, 
far  more  vividly  than  a  mass  of  wrought-iron  raised  above  the  weld- 
ing heat;  as  the  metal  cools,  the  sparks  become  intermittent,  and 
at  last  the  metal  remains  entirely  quiet,  excepting  a  multitude  of 
lines  vibrating  in  all  directions,  as  if  the  surface  were  covered*with 
thousands  of  wire-worms  in  great  activity  ;  this  effect  lessens  until 
the  metal  solidifies.  The  softest  iron  shows  most  of  this  play  of 
lines,  or  is  said  to  break  the  best. 

Iron  castings  are  generally  much  heavier  than  those  of  brass, 
and  the  melting  heat  of  the  metal  being  considerably  higher,  the 
quantity  of  gas  generated  is  very  much  greater ;  additional  care  is 
consequently  required  to  provide  for  its  escape,  or  the  explosions 
are  much  more  violent.  The  sand  is  punctured  at  many  places 
with  a  fine  wire,  before  the  removal  of  the  patterns ;  sometimes  also 
more  coarsely  as  soon  as  the  metal  has  become  solidified.  The 
gases  issuing  from  the  filled  moulds  are  often  lighted,  either  by  the 
red-hot  skimmer,  or  by  a  torch  of  straw  with  which  the  moulds  are 
flogged :  this  lessens  the  accumulation  of  gas  and  the  consequent 
risk  of  accident. 

The  pouring  of  very  large  objects  in  open  moulds,  such  as  plates, 
beams  and  girders,  is  a  very  beautiful  and  grand  sight.  The  metal 
is  led  from  the  furnace  through  a  gutter  lined  with  sand,  into  a 
large  trough  or  sow,  the  end  of  which  is  closed  with  a  shuttle  ;  when 
the  sow  is  full,  the  shuttle  is  raised ;  this  allows  the  metal  to  flow 
very  quickly  into  the  mould,  but  enables  it  to  be  kept  back  should 
it  be  unnecessarily  hot;  the  castings  made  in  open  moulds  are 
generally  covered  up  with  sand  as  soon  as  the  metal  is  set. 

The  above,  and  the  casting  of  smaller  objects,  such  as  flat  plates 
in  open  moulds,  may  appear  amongst  the  most  certain  modes  of 
procuring  sound  castings ;  but  unless  the  air  be  well  drawn  from 
the  lower  surfaces,  they  will  become  honeycombed  or  full  of  air- 
bubbles.  This  defect  is  avoided  by  making  the  sand-bed  sufficiently 
18 


274  THE   PKACTICAL   METAL-WOBKEB's  ASSISTANT. 

porous,  and  pricking  it  with  many  holes  just  below  the  surface,  to 
serve  as  horizontal  cu>-drains. 

•  A  far  greater  number  of  works  are  cast  in  close  moulds,  and  in 
the  horizontal  position ;  the  proportionate  quantity  of  metal  is  car- 
ried to  them  in  ladles;  skimmers  are  held  to  the  lips  of  the  moulds 
at  the  time  of  pouring,  to  keep  back  all  the  sullage  or  dross.  The 
number,  position,  and  height  of  the  runners,  are  determined  by  cir- 
cumstances ;  generally  not  less  than  two  apertures  are  provided, 
the  first  for  the  entry  of  the  metal,  the  second  for  the  escape  of 
the  air,  and  to  allow  the  metal  to  flow  through  the  mould  and  carry 
off  the  sullage. 

Sometimes  in  heavy  castings,  in  addition  to  the  runners  one  or 
more  large  heads  or  feeds  are  made  at  the  upper  part,  to  supply 
fluid  iron  as  the  metal  shrinks  in  the  act  of  solidifying ;  and  in  some 
such  cases  the  feed  is  pumped,  by  moving  an  iron  rod  up  and  down 
in  the  feed  to  keep  the  metal  in  motion,  so  that  for  a  time  the  metal 
may  freely  enter  and  the  air  escape,  to  increase  the  general  sound- 
ness of  the  mass.  The  pumping  should,  however,  be  discontinued 
the  moment  the  metal  begins  to  stiffen  and  clog  the  iron  rod,  or  in 
other  words  to  crystallize,  otherwise  mischief  instead  of  benefit  will 
accrue. 

Works  which  are  required  to  be  particularly  sound,  as  some 
cylinders,  pipes,  shafts  and  plungers,  are  cast  vertically ;  the  moulds 
are  sunk  in  the  earth,  and  well  rammed  to  enable  them  to  with- 
stand the  great  pressure  of  the  fluid  column,  without  becoming 
strained  or  bursting  open.  Such  objects  are  moulded  and  poured 
with  a  head,  or  an  additional  portion  about  one-third  the  length 
of  the  finished  casting,  as  mentioned  in  respect  to  brass  guns. 

In  pouring  cylinders  of  tolerably  large  size,  the  metal  is  conducted 
from  the  sow  through  two  sunk  passages  with  side  branches,  en- 
tering the  mould  in  the  direction  of  tangents  about  one-third  from 
the  bottom ;  these  keep  the  metal  in  circulation,  and  assist  the  rise 
of  the  sullage ;  cylinders  are  also  poured  through  holes  in  the  loam 
cake,  other  apertures  being  always  provided  in  it  for  the  escape  of 
the  air.  Beneath  the  iron  plate  upon  which  the  mould  is  built,  is 
placed  a  central  mass  of  hay-bands,  in  order  that  the  air  may  have 
free  passage  to  collect,  and  then  to  escape  upwards  to  the  surface 
of  the  earth,  through  one,  two,  three,  or  more  internal  or  external 
tubes,  as  the  case  may  be.  The  thick  cylinders  for  hydrostatic 
presses  are  closed  at  one  end,  and  those  cast  with  the  mouth  down- 
wards, require  an  air  tube  bent  at  each  end,  to  lead  from  the  core 
beneath  the  casting  to  the  surface  of  the  earth ;  the  gas  drives  out 
in  a  stream,  and  is  immediately  ignited  like  a  great  torch :  others 
prefer  casting  them  with  the  mouth  upwards,  in  order  that  less  risk 
may  exist  of  locking  up  air  within  the  casting. 

For  the  very  heaviest  works  the  three  or  four  furnaces  are 
usually  tapped  at  the  same  moment,  the  stream  from  every  one  is 
conducted  through  a  sand  trough,  and  they  all  unite  in  one  great 
trunk  leading  to  the  mould.  " 


CASTING   AND   FOUNDING.  275 

In  pouring  some  of  the  largest  cylinders,  the  trough  is  led  en- 
tirely round  the  top  of  the  loam  mould,  and  from  the  circular 
channel,  sometimes  as  many  as  thirty  runners,  every  one  of  which 
is  stopped  by  a  shovel  held  by  a  man  or  a  boy,  descend  to  the 
mould,  and  as  many  air  holes  are  made  between  the  ingates.  When 
the  foreman  sees  that  all  the  furnaces  are  in  full  run,  and  that  the 
channels  are  well  supplied,  he  gives  the  word,  "  up  shovels ;"  they 
rise 'at  the  instant,  and  allow  the  molten  stream  to  Deposit  itself  in 
its  temporary  resting-place. 

At  the  time  the  cylinder  is  poured,  all  the  precautions  explained, 
p.  266,  are  necessary  to  give  the  mould  sufficient  strength  to  resist 
the  pressure  of  the  fluid  metal ;  but  as  soon  as  it  becomes  set,  the 
conditions  are  altered,  and  this  resistance  must  be  removed  from 
the  inner  surface,  that  the  cylinder  may  shrink  in  cooling  without 
restraint  or  fracture.  Accordingly,  after  three  or  four  hours'  time, 
all  the  diametrical  iron  stays  are  knocked  away  by  a  vertical  weight 
or  monkey,  and  men  descend  by  iron  ladders  into  the  cylinder,  to 
break  down  the  brick  core.  The  heat  is  so  terrific,  that  they  can 
only  endure  it  for  a  minute  or  so  at  a  time,  but  still  the  precaution 
is  imperative :  and  even  in  comparatively  small  castings  of  hollow 
objects,  such  as  cylinders,  pans,  and  boxes,  it  is  desirable  to  break 
down  the  cores,  to  prevent  the  castings  from  scoring  or  breaking. 

Although  some  iron  castings  employed  for  bridges,  girders,  and 
even  for  machinery,  require  the  enormous  quantities  of  iron  re- 
ferred to,  on  the  other  hand  this  useful  metal  is  employed  for 
exceedingly  light  and  beautiful  castings,  abundant  examples  of 
which  may  be  seen  in  the  Berlin  ornaments  and  chains.  The 
links  of  most  of  the  Berlin  chains  are  connected  with  wrought- 
iron  wire,  but  Figs.  173  and  174  represent  a  chain  made  entirely 
by  the  process  of  casting. 

Figs.  173  174. 


Its  length  is  4  feet  10  inches.  It  consists  of  about  180  links; 
and  weighs  1$  oz.  avoirdupois.  It  was  thus  made :  The  larger 
links  a  a  were  first  cast  separately;  a  solid  model  of  the  chain 
about  8  inches  long,  with  core  prints,  as  in  Fig.  174,  was  then 
moulded.  The  links  a,  previously  smoked  to  prevent  the  adhesion 
of  the  metal,  were  first  laid  in  the  mould,  and  afterwards  the  sand 
cores  b  b,  and  a  separate  runner  was  made  to  every  one  of  the 
small  links  c  c,  so  as  to  unite  the  whole  when  poured. 

The  concluding  duty  of  the  iron-founder  is  to  remove  the  cast- 


276  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

ings  from  the  mould  and  to  break  off  the  runners.  After  this  all 
the  loose  sand  (whieh  is  reserved  for  making  the  partings  of  future 
moulds)  is  scraped  off  with  iron  shovels  and  wire  scratch  brushes, 
and  the  seams  are  smoothed  off  with  chisels  and  old  files. 

The  skin  or  crust  of  a  casting  made  in  a  sand  mould  is  in 
general  harder  than  that  of  a  loam  casting.  This  appears  to  occur 
from  the  former  being  partially  chilled  by  the  moisture  of  the  sand. 
In  some  cases,  as  in  the  teeth  of  wheels,  it  is  desirable  to  retain 
this  hard  sand  coat  on  account  of  its  greater  durability ;  but  when 
£he  crust  is  partially  removed  from  thin  or  slight  works,  it  con- 
stantly happens  that  they  spring  or  become  distorted  whilst  under 
the  treatment  of  tools,  from  the  general  balance  of  strength  being 
disturbed  by  the  partial  removal  of  the  crust.  This  gives  rise  to 
continual  interferences,  which  come  however  under  the  considera- 
tion of  the  mechanician  rather  than  of  the  founder. 

The  crust  of  the  casting,  which  always  retains  some  sand,  is 
very  destructive  to  the  tools,  unless  they  can  be  sent  in  deep 
enough  to  penetrate  to  the  clean  metal  beneath.  Wfren  but  little 
is  to  be  removed  from  the  casting,  or  that  they  are  wrought  with 
expensive  tools  and  circular  cutters,  it  is  desirable  to  pickle  the 
works,  or  to  undermine  the  sand  by  dissolving  a  little  of  the  metal 
with  some  acid. 

Iron  castings  are  pickled  with  sulphuric  acid  diluted  with  about 
twice  as  much  water.  The  castings,  if  small,  are  immersed  in  a 
trough  lined  with  lead ;  or  else  the  acid  is  sprinkled  over  them. 
In  two  or  three  days  a  thin  crust,  like  an  efflorescence,  may  be 
washed  off  with  the  aid  of  water  and  slight  friction.  ' 

Brass  and  gun-metal,  when  pickled,  require  nitric  acid  diluted 
with  four  to  six  times  as  much  water,  otherwise  the  rough  coat 
should  be  removed  with  an  old  file  or  a  triangular  scraper,  but 
which  is  less  effective  than  the  dilute  acid.  This  acid  liquor  should 
be  also  kept  in  leaden  vessels,  or  in  those  of  well-glazed  earthen- 
ware or  glass.  The  yellow  brass  is  much  improved  by  a  good  but 
equal  condensation  with  the  hammer,  and  in  fact  to  whatever  action 
the  metals  are  subjected,  whether  natural  in  the  mould,  or  artificial 
under  the  hammer  and  tools,  it  is  of  primary  importance  that  all 
parts  should  be  treated  as  nearly  alike  as  possible. 

NEW  METHOD  OF  MANUFACTURING  DROP  SHOT. — David  Smith, 
of  the  house  of  Le  Eoy  and  Co.,  263  Water  Street,  New  York, 
has  invented  and  put  into  practice  a  new  mode  of  manufacturing 
drop  shot.  The  chief  feature  of  this  invention  consists  in  causing 
the  fused  metal  to  fall  through  an  ascending  current  of  air,  which 
shall  travel  at  such  a  velocity  that  the  dropping  metal  shall  come 
iu  contact  with  more  particles  of  air,  in  a  short  tower,  than  it 
would  in  falling  through  the  highest  towers  before  in  use. 
Fig.  175  is  a  vertical  sectional  elevation  of  a  sheet  metal  cylinder, 
set  up  as  a  tower  within  a  building,  and  may  be  about  20  inches 
internal  diameter,  and  50  feet  high  or  less.  This  tower,  although 
mentioned  in  Smith's  patent,  is  now  dispensed  with  in  the  middle 


CASTING   AND   FOUNDING. 


277 


of  the  height,  so  that  only  an  open  space  remains.     Fig.  176  is  a 


plan  at  the  line  a  b  ;  Fig.  177  is  a  plan  at  the  line  qr;  Fig.  178  is 
a  section  at  op ;  and  Fig.  179  is  a  section  at  m  n,  Fig.  175 


Fig.  178. 


Fig.  179 


C  is  a  water-cistern  beneath  the  tower.  B  is  a  pipe  from  the 
blowing  apparatus  leading  into  the  annular  chamber  /;  the  upper 
.surface  g  is  perforated  as  shown  in  Fig.  177,  to  dispense  the  ascend- 


278  THE    PRACTICAL    METAL-WORKER  S   ASSISTANT. 

ing  air.  The  outer  side  of  this  annular  ring  /  forms  the  base  of  a 
frustum  of  a  cone,  forming  the  tower  D,  passing  the  blast  through 
the  frame  y  y,  Fig.  178  ;  and  in  Fig.  175  is  shown  to  support  a 
cylindrical  standard  E,  the  upper  central  portion  of  which  receives 
the  pouring  pan  A.  This  pan  is  charged  with  each  separate  size 
of  shot.  Bound  the  pouring  pan  A  is  a  circular  waste  trough  z. 
The  object  of  this  arrangement  is  that  the  fluid  metal  running 
through  the  pouring  pan  A  into  the  ascending  current  of  air,  will 
be  operated  upon  in  the  same  manner  as  if  it  fell  through  stagnant 
air  of  great  height  The  shot  falls  through  the  open  centre  of  the 
ring  /  into  the  water  cistern  C,  where  a  shoot  t  carries  it  into  the 
tub  S,  which  when  full  may  be  removed  through  x,  an  aperture  in 
the  cover  of  the  cistern. 


CHAPTER  XVI. 

WORKS  IN  SHEET  METAL,   MADE  BY   JOINING. 

ON  MALLEABILITY,  ETC.  ;  DIVISION  OF  THE  SUBJECT. — The 
process  of  casting,  which  has  been  recently  considered  under  so 
great  a  variety  of  forms,  is  one  of  the  most  valuable  courses  of 
preparation  to  which  the  metallic  materials  are  submitted.  In  the 
foundry,  the  metals  are  made  to  assume  an  infinitude  of  the  most 
arbitrary  shapes,  but  which  are  in  general  more  or  less  thick  or 
'massive.  It  is  now  proposed  to  consider  a  few  of  the  methods  and 
principles  of  a  very  extensive  and  serviceable  employment  of  the 
malleable  metals  and  alloys,  which  (excepting  iron)  are  cast  into 
thick  slabs  or  plates,  and  then  laminated  into  thin  sheets  between 
cylindrical  rollers. 

Rollers  have  been  used  for  a  considerable  period  in  the  manu- 
facture of  sheets  of  malleable  iron,  steel,  and  copper,  when  in  the 
red-hot  state,  but  most  others  of  the  metals  and  alloys  are  rolled 
whilst  cold ;  and  which  economic  application  of  power  often  nearly 
supersedes  the  use  of  the  hammer,  as  it  performs  its  function  in  a 
more  uniform  and  gradual  manner,  and  at  the  same  time  increases 
tp  the  utmost  the  hardness,  tenacity,  elasticity  and  ductility  of 
such  of  the  metals  and  alloys  as  are  submitted  to  this  and  similar 
courses  of  preparation  for  the  arts.  These  processes  of  condensa- 
tion cannot  be  carried  to  the  extreme  without  frequent  recurrence 
at  proper  intervals  to  the  process  of  annealing  ;  and  in  rolling  the 
thinnest  sheets  of  metal,  several  are  frequently  sent  through  the 
rollers  at  the  same  time ;  but,  as  in  the  instances  of  tin-foil,  gold 
and  silver  leaf,  and  some  others,  the  hammer  is  again  resorted  to 
after  the  metals  have  been  rolled  as  thin  as  they  will  economically 
admit  of,  in  this  process  of  part-manufacture. 


WORKS   IN   SHEET   METAL.  279 

None  of  these  preparations  of  the  metals  can  go  on  without  u 
material  internal  change  of  their  substance,  to  which  the  celebrated 
Dr.  Dalton  thus  refers :  "  Notwithstanding  the  hardness  of  solid 
bodies,  or  the  difficulty  of  moving  the  particles  one  amongst  the 
other,  there  are  several  that  admit  of  such  motion  without  fracture, 
by  the  application  of  proper  force,  especially  if  assisted  by  heat. 
The  ductility  and  malleability  of  the  metals  need  only  be  men- 
tioned. It  should  seem  the  particles  glide  along  each  other's  sur- 
face, somewhat  like  a  piece  of  polished  iron  at  the  end  of  a  magnet, 
without  being  at  all  weakened  in  their  cohesion." 

This  gliding  amongst  the  particles  of  metals  is  exemplified  by 
the  action  of  thinning  them  by  blows  of  the  hammer  ;  likewise  by 
the  actions  of  laminating  rollers  and  the  draw-bench,  in  which 
cases  the  external  layers  of  the  metals  are  retarded  or  kept  back 
as  it  were  in  a  wave,  whilst  the  central  stream  or  substance  con- 
tinues its  course  at  a  somewhat  quicker  rate.  The  necessity  for 
annealing  occurs  when  the  compression  and  sliding  have  arrived 
at  the  limit  of  cohesion.  Beyond  this  the  parts  would  tear  asun- 
der, and  produce  such  of  the  internal  cracks  and  seams,  met  with 
in  sheet-metal  and  wire,  as  are  not  due  to  original  flaws  and  air- 
bubbles,  which  have  become  proportionally  elongated  in  the  course 
of  the  manufacture  of  these  materials. 

A  sliding  or  gliding  of  a  very  similar  nature  occurs  also  in 
every  case  in  which  the  metals  are  bent ;  and  this  differs  only  in 
degree,  whether  we  consider  it  in  reference  to  a  massive  beam,  a 
permanently  flexible  spring,  a  piece  of  thin  sheet-metal,  or  a  film 
of  gold  leaf.  For  instance,  the  curvature  of  a  cast-iron  beam, 
originally  straight,  is  produced  by  the  stretching  or  extension  of 
the  lower  edge,  and  the  shortening  or  compression  of  the  upper 
edge,  the  central  line  remaining  unaltered  during  the  process,  ex- 
cept it  is  bent.  In  like  manner  a  spring  derives  its  elasticity  from 
the  extension  and  compression  of  its  opposite  surfaces  at  even- 
flexure  ;  and  the  spring  remains  permanent,  or  endures  its  work 
without  alteration  of  form,  when  the  bending  is  not  carried  beyond 
its  limit  of  elasticity  ;  but  when  it  is  bent  beyond  a  certain  point, 
the  spring  either  retains  a  permanent  set  or  distortion,  or  it  will 
Ixreak.  In  the  same  manner  the  beam,  when  only  bent  to  the  limit 
of  its  elasticity,  returns  to  its  original  form  when  the  load  is  re- 
lieved, and  the  constant  study  of  the  engineer  is  so  to  proportion 
the  beam  that  it  may  never  be  required  to  exceed  nor  even  to 
arrive  at  the  limit  of  its  elastic  force.  For  those  parts  of  mechan- 
ism exposed  to  sudden  shocks  and  strains,  he  will  employ 
wrought-iron,  the  cohesive  strength  of  which  is  considerablv 
greater  than  that  of  cast-iron,  although  less  than  that  of  steel, 
which  is  the  strongest  and  most  permanently  elastic  of  all  metallic 
substances. 

The  thin  metals  also  possess  some  elasticity,  biit  this  dies  away 
before  they  reach  the  tenuity  of  leaf  gold  in  which,  however,  the 
bending  cannot  be  accomplished  without  a  similar  change  in  the 


280  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

arrangement  of  its  opposite  sides,  although  the  difference  is  be- 
yond the  reach  of  our  physical  senses. 

If  we  desire  to  wrap  a  piece  of  gold  leaf  around  a  cylinder  of 
half  an  inch  diameter,  so  small  is  the  resistance  that  the  least  puff 
of  breath  suffices.  A  piece  of  thin  tin-foil  offers  no  more  resist- 
ance than  writing-paper.  Thin  latten-brass,  or  China  tea-lead,  is 
bent  more  easily  than  a  card  ;  brass  and  iron  the  thirtieth  or  forti- 
eth of  an  inch  thick,  could  be  readily  bent  with  a  wooden-mallet ; 
but  metal  of  one-eighth  of  an  inch  thick  would  call  for  smart  blows 
of  a  hammer,  and  in  iron  and  stee*l  the  further  assistance  of  heat 
would  be  likewise  required,  because  in  the  last  case  a  very  con- 
siderable amount  of  the  sliding  motion  of  the  metal  would  be  called 
into  play. 

For  example,  the  piece  of  metal  £  of  an  inch  thick,  was  originally 
flat  and  of  the  same  size  on  its  opposite  surfaces ;  whereas  now, 
neglecting  any  alteration  of  thickness,  the  inner  part  would  equal 
the  circumference  of  a  circle  J  an  inch  diameter,  and  the  outer  that 
of  a  circle  of  f  inch  diameter ;  or  it  would  become  1  £  and  2^ 
inches  long  respectively  on  its  opposite  surfaces.  To  produce  this 
change  of  dimensions  would  necessarily  require  far  greater  force 
than  the  bending  of  the  gold  leaf,  the  internal  and  external  meas- 
ures of  which,  viewed  as  a  cylinder,  could  be  ascertained  alone  by 
calculation,  and  not  by  ordinary  means.  On  the  other  hand,  the 
sliding  of  the  thick  sheet  of  metal  would  be  illustrated  most  dis- 
tinctly, if  several  pieces  of  writing-paper,  equal  to  the  original 
metal  individually  in  surface  and  collectively  in  thickness,  were 
wrapped  around  the  same  cylinder.  The  inner  paper  would  ex- 
actly meet,  the  outer  would  present  an  open  seam  £  inch  wide. 
The  metals  possessed  of  the  malleable  property  undergo  a  nearly 
equal  change  in  their  arrangement ;  but  the  unmalleable  or  brittle 
metals  break. 

Several  of  the  processes  of  working  the  sheet  metals  are  closely 
analogous  to  those  employed  in  forging  ordinary  works  in  iron  and 
steel, — the  difference  being  mainly  such  as  arise  from  the  thin  and 
thick  states  of  the  respective  materials,  and  their  relative  degrees 
of  rigidity  or  resistance.  The  illustrations  will  be  selected  indis- 
criminately from  various  trades  in  which  the  sheet  metals  are  em- 
ployed. It  appears  desirable,  however,  to  separate  the  subject  into 
two  principal  parts,  namely,  the  formation  of  objects  some  lines  of 
which  are  straight,  and  the  formation  of  objects  no  lines  of  which 
are  straight. 

The  first  division  comprehends  all  objects  with  plane,  cylindri- 
cal or  conical  surfaces,  such  as  may  be  produced  in  pasteboard  by 
cutting  out  the  respective  sides,  either  separately  or  in  clusters,  and 
combining  them  in  part  by  bending,  and  in  part  by  cement.  Simi- 
lar works  in  metal  are  often  produced  by  the  precisely  analogous 
means  of  cutting,  bending,  and  uniting,  and  which  call  for  increase 
of  strength  in  the  methods  proportioned  to  the  rigidity  of  the 
materials. 


WORKS   IX   SHEET   METAL.  281 

The  second  division  comprehends  all  objects  with  surfaces  of 
double  curvature,  including  spherical,  elliptical,  parabolical,  and 
arbitrary  surfaces,  as  in  reflectors,  vases,  and  a  thousand  other 
things,  none  of  which  forms  can  be  produced  in  stiff  pasteboard, 
because  this  material  is  incapable  of  being  extended  or  contracted 
in  different  parts  in  the  manner  of  sheet  metal.  This  is  easily 
shown,  by  the  following  case,  amongst  others. 

^errestrial  globes  are  covered  with  thin  paper,  upon  which  the 
delineation  of  the  surface  of  the  earth  has  been  printed :  the  paper 
may  be  cut  into  twelve  gores,  or  fish-shaped  pieces,  all  including 
thirty  degrees  from  pole  to  pole.  A  globe  is  usually  covered  with 
26  pieces  of  paper,  namely,  2  pole  papers,  or  circles  including  30° 
around  each  pole ;  and  24  gores  meeting  at  the  equator.  Sometimes 
the  gores  extend  from  the  pole  to  the  equator;  every  gore  has  then 
a  narrow  curved  central  notch  extending  30°  from  the  equator. 
But  the  same  gores  cut  out  of  pasteboard  could  not  be  applied  to 
the  surface  of  a  globe,  as  pasteboard  does  not  admit  of  that  degree 
of  gradual  extension  and  contraction,  required  for  the  production 
of  spherical  and  similar  raised  forms,  from  pieces  originally  flat,  but 
will  become  abruptly  bent  and  torn  in  the  attempt. 

On  the  contrary,  a  round  disk  of  metal  may  be  beaten  into  a 
hemisphere,  or  nearly  into  a  sphere ;  but  even  thin  paper  is  only 
possessed  of  this  quality  in  a  very  limited  degree,  for  the  globe 
could  not  be  smoothly  covered  with  so  few  as  two,  three,  or  four 
pieces  of  the  thinnest  paper  without  its  puckering  up,  showing  that 
some  parts  of  the  material  are  in  excess.  The  gliding  property,  or 
that  of  malleability  and  ductility,  possessed  by  the  metals,  is  indis- 
pensable to  adapt  the  flat  plate  to  the  sphere,  by  stretching  the 
central  portion  and  gathering  up  the  marginal  part,  an  action  that 
admits  of  some  comparison  to  the  extension  or  compression  of  the 
slides  of  a  telescope,  except  that  the  metal  becomes  thicker  or 
thinner  instead  of  being  duplicated  on  itself. 

WORKS  IN  SHEET  METAL,  MADE  BY  CUTTING,  BENDING,  AND 
JOINING. — Every  one  in  early  life  has  made  the  first  step  towards 
the  acquirement  of  the  various  arts  of  working  in  sheet  metal,  in 
the  simple  process  of  making  a  box  or  tray  of  card ;  namely,  by 
doubling  up  the  four  margins  in  succession  to  an  equal  width, 
then  cutting  out  the  small  squares  from  the  angles,,  and  uniting  the 
four  sides  of  the  box,  either  edge  to  edge,  by  paste,  sealing-wax,  or 
thread,  or  in  similar  manners  by  lapped  or  folded  joints.  A  dif- 
ferent mode  is  to  make  the  sides  of  the  box  as  a  long  strip,  folded 
at  all  the  angles  but  one ;  or  lastly,  the  bottom  and  sides  may  be 
cut  out  entirely  detached,  and  united  in  various  ways. 

In  the  above,  and  also  in  the  most  complicated  vessels  and  solids, 
it  is  necessary  to  depict  on  the  material  the  exact  shape  of  every 
plane  superficies  of  the  work,  as  in  the  plans  and  elevations  of  the 
architect ;  and  these  may  be  arranged  in  any  clusters  which  admit 
of  being  folded  together,  so  as  to  constitute  part  of  the  joints  by 
bending  the  material.  Thus,  a  hexagonal  box,  Fig.  180,  can  be 


282 


THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 


made  by  drawing  first  the  hexagon  required  for  the  bottom,  as  in 
Fig.  181,  and  erecting  upon  every  side  of  the  same  a  parallelogram 
equal  to  one  of  the  sides,  which  in  this  case  are  all  exactly  alike ; 
otherwise  the  group  of  sides  can  be  drawn  in  a  line,  as  in  Fig.  182, 
and  bent  upon  the  joints  to  the  required  angle,  or  120  degrees. 
Either  mode  would  be  less  troublesome  than  cutting  out  seven 
detached  pieces  and  uniting  them  ;  the  addition  of  one  more  hexa- 
gon, dotted  in  Fig.  182,  would  serve  to  complete  the  top  of  the 
hexagonal  prism,  by  adding  a  cover  or  top  surface. 

The  same  mode  will  apply  to  polygonal  figures  of  all  kinds, 
regular  or  irregular ;  thus  Fig.  183  would  be  produced  when  the 
group  of  sides  in  184  were  bent  around  the  irregular  octagonal 
base ;  or  that  the  sides  of  185  were  separately  turned  up 


Figs.  180 


183 


185. 


The  cylinder  is  sometimes  compared  with  a  prism  of  so  many 
sides,  that  they  melt  into  each  other  and  become  a  continuous 
curve ;  and  if  the  hexagon  in  Fig.  182  were  replaced  by  a  cir*cle, 
and  the  group  of  sides  were  cut  out  of  equal  length  with  the  cir- 
cumference of  that  circle,  and  in  width  equal  to  the  height  of  the 
vessel,  any  required  cylinder  could  be  produced.  And  in  like 
manner  any  vessel  of  elliptical  or  similar  forms,  or  those  with  par- 
allel sides  and  curved  ends,  and  all  such  combinations,  could  be 
made  in  the  manner  of  Fig.  184  (provided  the  sides  were  perpen- 
dicular), by  cutting  out  a  band  equal  in  length  to  the  collective 
margin  of  the  figure,  as  measured  by  passing  a  string  around  it ; 
or  the  sides  might  be  made  of  two,  or  several  pieces,  if  more  con- 
venient, or  if  requisite  from  their  magnitude. 

All  prismatic  vessels  require  parallelograms  to  be  erected  on 
their  respective  bases ;  but  pyramids  require  triangles,  and  frustums 
of  pyramids  require  trapezoids,  as  will  be  explained  by  Figs.  187 


WORKS   IX   SHEET    METAL.  283 

and  188,  which  are  the  forms  in  which  a  single  piece  of  metal 
must  be  cut,  if  required  to  produce  Fig.  186.  Every  one  of  the 
group  of  sides,  must  be  individually  equal  to  one  of  the  sides  of  the 
pyramid,  whether  it  be  regular  or  irregular,  and  186  being  an  erect 
and  equilateral  figure,  all  the  sides  in  187  and  188  are  required  to  be 
alike,  and  would  be  drawn  from  one  templet :  an  irregular  pyramid 
would  require  all  its  superficies  to  be  drawn  to  their  absolute  forms 
and  sizes. 


Figs.  186 


187 


The  cone  is  sometimes  compared  with  a  pyramid  with  exceed- 
ingly numerous  sides  (as  the  cylinder  is  compared  with  the  prism), 
and  Fig.  189,  intended  to  make  a  funnel  or  the  frustum  of  a  cone 
of  the  same  proportions  as  186,  illustrates  this  case.  The  sides  of 
the  cone  are  extended  until  they  meet  in  the  centre  o,  Fig.  186,  and 
then  with  the  slant  distances  o  a,  and  o  b,  the  two  arcs  a  a,  and  b  b, 
are  drawn  with  the  compasses,  from  the  centre  o ;  and  so  much  of 
the  arc  a  a,  is  required  as  equals  the  circumference  a,  of  the  cone : 
the  margins  a  b,  a  b,  are  drawn  as  two  radii.  When  the  figure  is 
curled  up  until  the  radial  sides  meet,  it  will  exactly  equal  the  cone, 
and  the  similitude  between  Figs.  188  and  189  is  most  explanatory, 
as  189  is  just  equal  to  the  collective  group  of  the  sides  required  to 
form  the  pyramid. 

It  will  now  be  easily  seen  that  mixed  polygonal  figures,  such  as 
Figs.  190,  192,  and  194,  may  be  produced  in  a  similar  manner, 
provided  their  sides  are  radiated  from  the  square,  the  hexagonal 
or  other  bases,  in  the  manner  of  Figs.  191,  193,  195,  but  the  sides 
of  the  rays  not  being  straight,  it  is  no  longer  possible  to  group 
them  by  their  edges,  as  in  Figs.  182,  184,  and  188.  The  object 
with  plane  surfaces,  Fig.  190,  is  only  the  meeting  of  two  pyramids, 
at  the  ends  of  a  prism,  and  when  unfolded,  as  in  Fig.  191,  the  centre 
a,  is  equal  to  the  base  a,  of  the  object ;  the  sides  b,  radiate  and  ex- 


284 


THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 


pand  from  the  hexagon  at  the  angle  of  the  faces  of  the  inverted  or 
lower  pyramid  b,  and  their  vertical  height  in  the  sheet  is  equal  to 
the  slant  height  in  the  vessel ;  the  superficies  c,  are  those  of  a  prism, 
therefore  they  continue  parallel,  and  have  the  vertical  height  of  the 
part  c,  of  the  figure ;  ^lastly,  the  sides  d,  again  contract  as  in  the 
original,  and  at  the  same  angle  as  the  sides  of  the  six  upper  faces  ; 
in  a  word,  the  faces  b,  c,  d,  are  identical  in  the  vase  and  in  the  radi- 
ated scheme. 


Figs.  190 


191 


195. 


Should  the  vessels,  instead  of  planes,  have  surfaces  of  single  cur- 
vature, as  in  Figs.  192  and  194,  the  method  is  nearly  as  simple. 
The  object  is  drawn  on  paper,  and  around  its  margin  are  marked 
several  distances,  either  equal  or  unequal,  and  horizontal  lines  or 
ordinates  are  drawn  from  all  to  the  central  line.  The  radiating 
pieces  for  constructing  the  polygonal  vases  are  represented  in  Figs. 
193  and  195,  in  which  the  dotted  lines  are  parallel  with  the  sides 
of  the  hexagons  or  the  bases,  and  at  a  distance  equal  to  those  of 
the  steps  1,  2,  3,  to  8,  around  the  curve  of  the  intended  vases ;  the 
lengths  of  these  lines,  or  ordinates,  1  1,  2  2,  3  3,  are  in  regular 
hexagonal  vessels  exactly  the  same  in  the  radiated  plans  as  in  the 
respective  elevations,  because  the  side  of  the  hexagon  and  the  radius 
of  its  circumscribing  circle  are  alike. 

In  all  other  regular  polygonal  vessels  the  new  ordinates  will  be 
reduced  for  figures  of  8,  10,  and  12  sides,  in  the  same  proportions 
as  the  sides  of  these  respective  polygons  bear  to  the  radii  of  their 
circumscribing  circles,  and  the  ordinates  for  3,  4,  and  5  sided 
figures  will  be  similarly  increased. 

All  the  above  cases  could  be  accurately  provided  for  without 
any  calculation,  by  the  employment  of  a  very  simple  scale  repre- 


WORKS   IN   SHEET   METAL.  285 

j 

scntecl  in  Fig.  196,  in  which  the  angle  3  of,  shall  contain  120  de- 
grees, or  the  third  of  a  circle;  4  of,  90  degrees,  or  the  fourth; 
5  of,  72,  or  the  fifth ;  6  of,  60,  or  the  sixth;  and  8,  10,  and  12,  re- 
spectively the  8th,  10th,  and  12th  parts  of  a  circle.  The  circular 
arcs  are  struck  from  the  centre  o,  and  may  be  the  6th,  8th,  10th  of 
an  inch,  or  any  small  distance  apart. 

To  learn  the  altered  value  of  any  ordinate,  as  for  constructing  a 
vase, like  the  several  figures  190,  192,  194,  but  with  10  sides;  we 
will  suppose  the  original  ordinate  to  reach  from  o  to  x  on  the 
radius  of,  the  required  measure  would  be  the  length  of  the  arc 
x  x ,  where  intersected  by  the  line  10,  or  that  for  a  decagon ;  but 
it  would  be  more  convenient  to  make  the  angle  half  the  size,  as 
then  the  new  ordinate  would  be  at  once  bisected,  ready  for  being 
set  off'  on  each  side  the  central  line  of  the  radiated  plan.  When 
one  side  had  been  carefully  formed,  a  curved  templet  or  gage 
would  be  made  to  the  shape,  by  which  all  the  other  sides  could  be 
drawn. 

For  polygonal  vessels  with  unequal  sides,  such  as  Fig.  197,  the 
curvatures  of  the  edges  of  the  rays  will  be  identical,  notwithstand- 
ing the  difference  of  the  sides.  For  example,  the  octagon  drawn 
in  the  one  corner  shows  that  the  figure  resembles  the  regular  octa- 
gon as  far  as  the  angles  are  considered;  and  that  the  regular 
octagon  may  be  considered  to  be  cut  into  four  quarters  and  to  be 
removed  to  the  four  corners,  by  the  insertion  of  the  two  pairs  of 
intermediate  pieces  a  a,  and  b  b,  which  latter  would  necessarily  be 
parallel.  In  the  like  manner  a  pyramidal  vessel  built  upon  the 
same  base,  would  require  equal  angles  for  all  its  sides. 

It  would  have  been  easy  to  have  extended  these  particulars  to 
numerous  other  figures,  such  as  the  regular  geometrical  solids, 
oblique  solids,  and  many  others,  but  enough  has  been  advanced  to 
explain  the  cases  of  ordinary  occurrence,  and  in  the  delineations 
of  which,  the  tinman,  coppersmith,  and  others  are  very  expert. 

197. 


Much  of  that  which  has  been  stated,  as  it  will  eventually  appear, 
has  been  partly  advanced  in  elucidation,  on  the  less  apparent 
methods  practised  in  making  similar  forms  out  of  flat  plates,  by 
the  process  called  raising ;  this  is  done  with  the  hammer  alone,  by 
stretching  some  parts  of  the  metal  and  contracting  others  (the 


286 


THE   PRACTICAL   METAL-WORKER  S  ASSISTANT. 


drawing  and  upsetting  of  the  blacksmith),  a  process  not  required  in 
any  of  the  foregoing  figures,  the  whole  of  which  might  be  made  in 
pasteboard,  a  material  that,  as  before  observed,  does  not  admit  of 
being  raised  or  bulged  into  figures  of  double  curvature. 

The  various  works  having  been  drawn  upon  the  sheet  of  metal, 
the  first  process  is  to  cut  them  out ;  this  is  almost  always  done 
with  the  shears;  sometimes,  however,  for  thick  metal,  the  cold- 
chisel  and  hammer  are  used,  the  work  being  laid  upon  the  bare 
anvil  or  upon  a  cutting-plate,  as  in  forging ;  occasionally  the  metal 
is  fixed  in  the  jaws  of  the  tail-vice,  and  cut  off  with  the  cold-chisel 
applied  in  contact  with  the  vice ;  the  edge  of  the  chisel  is  placed 
nearly  parallel  with  the  jaws,  which  serve  as  a  guide.  In  some 
cases  very  long  vices,  with  a  screw  at  each  end,  are  used  in  a  simi- 
lar manner,  for  the  thick  iron  plates  employed  for  boilers ;  but  the 
shears  are  the  most  generally  convenient. 

Although  the  tools  used  in  working  the  sheet-metals  are  ex- 
tremely various  as  regards  their  sizes  and  specific  forms,  they  may, 
with  the  exception  of  the  shears  and  soldering-tools,  be  principally 
resolved  into  numerous  varieties  of  hammers,  anvils,  swage-tools, 
and  punches.  Figs.  198  to  212  represent  some  few  of  the  most 
common  of  these  tools,  which  are  used  alike  both  in  bent  and 


205 


raised  works,  and  their  close  resemblance  to  those  for  ordinary 
forging  in  iron  and  steel  will  not  escape  observation.  The  most 
remarkable  points  of  difference  are  in  their  greater  height  and 
length,  which  enable  them  to  be  applied  to  the  interior  of  large 


WORKS   IN   SHEET   METAL.  287 

objects,  and  also  in  their  square  shanks,  by  which  they  are  fixed 
in  holes  in  the  wooden  blocks  and  benches. 

The  hammers  are  nearly  alike  at  both  ends ;  many  of  them 
have  circular  faces,  either  flat  or  convex  ;  others  resemble  the 
straight  or  cross-panes  of  ordinary  hammers,  and  are  also  either 
flat  or  convex ;  and  those  used  in  finishing,  are  exceedingly  bright, 
in  order  that  they  may  impart  their  own  degree  of  polish  to  the 
work,  which  process  is  called  planishing. 

When  thin  metal  is  struck  between  tools  both  of  which  are  of 
metal,  it  is  invariably  more  or  less  thinned ;  and  should  the  blows 
be  given  partially,  such  parts  will  become  stretched  or  cockled,  £nd 
will  distort  the  general  figure.  It  is  therefore  usual,  whenever 
admissible,  to  employ  wooden  hammers  of  the  forms  described, 
and  also  wooden  blocks  or  anvils  when  metal  hammers  are  used  ; 
reserving  the  employment  of  tools  both  of  metal,  either  for  the  con- 
cluding steps,  or  for  those  cases,  where  from  the  substance  of  the 
metal  and  the  nature  of  the  work,  the  wooden  hammers  would-  be 
ineffective,  or  a  greater  definition  of  form  is  required  than  wooden 
tools  could  give. 

The  anvil  used  by  the  coppersmith  and  similar  workmen  is 
usually  square,  say  from  six  to  eight  inches  on  every  side ;  and  the 
smaller  anvils,  which  are  called  stakes,  and  also  teests,  are  of  pro- 
gressively smaller  ^izes,  down  to  half  an  inch  square,  and  even 
less.  Some  of  them  have  one  edge  rounded  like  201 ;  others  have 
rounded  faces  as  202  and  203 ;  a  few  assume  the  form  of  a  rounded 
ridge,  like  Fig.  205  ;  and  many  have  bulbs  or  buttons,  as  if  turned 
in  the  lathe,  as  in  Fig.  206. 

The  beak-irons  are  also  very  unlike  those  used  by  the  smith ; 
they  are  seldom  attached  to  the  anvil,  and  are  often  exceedingly 
long,  as  in  Fig.  199 :  some  few,  for  more  accurate  purposes,  are 
turned  in  the  lathe  to  the  conical  form,  like  204 ;  these  are  held  in 
the  vice,  the  jaws  of  which  enter  grooves  in  the  shank ;  and  man- 
drels four  to  six  feet  long,  u'sed  for  making  long  pipes,  are  attached 
to  the  bench  by  long  rectangular  shanks  and  staples. 

Fig.  198,  the  hatc/td-stake,  is  from  two  to  ten  inches  wide ;  it  is 
very  much  used  for  bonding  the  thin  metals,  in  the  same  manner 
as  the  rectangular  edge  of  the  anvil  is  used  for  those  which  are 
thicker  ;  a  cold-chisel  fixed  in  the  vice  forms  a  small  hatchet-stake ; 
207  is  the  creasing-tool  for  making  small  beads  and  tubes  ;  208  is 
the  scam-set  for  closing  the  seams  prepared  on  the  hatchet-stake ; 
209  is  a  hollow  and  210  a  solid  punch;  the  cutting  edge  of  the 
former  meets  at  about  the  angle  of  fifty  degrees,  the  latter  is  solid 
at  the  end  for  small  holes;  both  are  struck  upon  a  thin  plate  of 
lead  or  solder  laid  upon  tho  stake;  211  is  a  riveting-set  or  punch 
for  the  heads  of  rivets ;  and  212  is  the  swage-tool,  a  miniature  of 
the  tilt-hammer,  t<>  which  a  great  variety  of  top  and  bottom  tools, 
or  creases,  are  added,  which  greatly  economize  the  labor  of  making 
dilli'ivnt.  mouldings  and  lioss.-s;  tin-  stop  is  used  to  retain  tin-  par- 
allelism of  the  moulding!  with  tin-  ed;.n-  »f  the  metal,  and  a  similar 
stop  is  also  at  times  applied  to  the  hatchet-stake,  198. 


288  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

The  sides  of  the  vessels  represented  in  Figs.  180  to  195,  if  the 
metal  were  thin,  would  be  bent  to  the  required  angles  by  laying 
the  metal  horizontally  upon  the  hatchet-stake,  with  the  lines  ex- 
actly over  the  edge  of  the  same,  and  blows  would  be  given  with 
the  mallet,  (or  with  the  hammer  for  more  accurate  angles),  so  as  to 
indent  the  metal  with  the  edge  of  the  stake  ;  it  would  be  then  bent 
down  with  the  fingers,  unless  the  edge  were  very  narrow  as  for  a 
seam,  when  the  mallet  would  be  alone  used.  Thicker  metal  is 
more  commonly  bent  over  the  square  edge  of  the  anvil,  as  in  Fig. 
59,  p.  104,  a  square  set  or  hammer  being  held  upon  its  upper  sur- 
face ;  and  sometimes  the  work  is  pinched  fast  in  the  vice,  and  it  is 
bent  over  with  the  blows  of  a  flat-ended  punch  or  set,  applied 
close  in  the  angles,  and  then  hammered  down  square  with  the 
hammer  ;  very  strong  metal  is  seldom  bent  in  this  manner,  but  the 
sides  of  objects  are  then  made  separately,  and  united  in  some  of 
the  ways  which  will  be  explained. 

In  bending  thin  metals  either  to  circular  or  other  curves,  they 
are  held  on  the  one  edge  in  the  hand,  and  curled  on  the  opposite 
edge  over  beak-irons  or  triblets  with  the  mallet ;  when  the  metal 
is  too  stubborn  or  too  narrow  to  be  thus  held  in  the  hand  (as  the 
copper-smith  scarcely  ever  uses  tongs,  except  at  the  fire),  the  metal 
is  driven  into  a  concave  tool  to  curl  up  the  edges.  For  instance, 
the  crease,  Fig.  207,  is  frequently  employed  for  making  small 
tubes  or  edging;  the  strip  of  metal  is  laid  over  the  appropriate 
groove,  and  an  iron  wire  is  driven  down  upon  it  with  the  mallet ; 
this  bends  it  like  a  wagon-tilt ;  the  edges  are  then  folded  down 
upon  the  wire  with  the  mallet,  and  it  is  finished  by  a  top  tool,  or 
a  punch,  Fig.  208,  having  a  groove  of  similar  concavity  or  radius 
to  that  in  the  crease. 

For  half-round  strips,  the  crease  together  with  the  round  wire 
suffice,  or  they  would  be  more  quickly  made  in  the  swage-tool, 
212,  and  which  might  in  this  manner  be  made  to  produce  any  par- 
ticular section  or  moulding,  and  that  at  any  distance  from  the  edge 
by  means  of  the  stop  or  gage.  Large  tubes  are  always  finished 
upon  beak-irons,  such  as  Fig.  199,  the  round  ends  of  which  serve 
for  curvilinear,  and  the  square  ends  for  rectilinear  works. 

Figs.  213  214. 

*     b 


All  the  sheet  metals  up  to  the  thickest  boiler  plate  are  treated 
much  after  the  same  general  methods ;  large  cast-iron  moulds  of 


WORKS   IN   SHEET   METAL. 


289 


various  sweeps  are  employed,  the  stout  iTon  being  heated  to  red- 
ness, and  set  into  them  with  set  hammers  struck  with  the  sledge. 
When  a  circular  bend  is  wanted  in  the  centre  of  a  long  piece,  it 
is  conveniently  and  accurately  done  by  bending  it  over  a  ridge, 
such  as  a  parallel  plate  with  a  rounded  edge,  or  a  triblet,  the  ends 
of  the  work  serving  for  a  purchase,  or  as  levers.  Thus  Fig.  213 
shows  the  common  mode  of  bending  thick  plates  to  the  form  of 
the  piece,  d  b,  cf,  for  the  internal  flues  of  marine  boilers ;  the  plate ; 
is  heated  to  redness  in  the  middle,  and  pressed  down  until  a  c 
assume  the  positions  d  c'.  r  ,,» 

In  a  similar  manner,  to  bend  long  strips  into  easy  curves,  such 
as  for  cylindrical  vessels,  the  tinmen  use  &  former,  Fig.  214,  a  cylin- 
drical piece  of  wood  from  two  to  four  inches  in  diameter,  and  two 
feet  long,  turned  with  a  pivot  at  the  one  end ;  the  pivot  is  laid 
upon  the  edge  of  the  bench,  and  the  man  rests  his  chest  against 
the  other  extremity  of  Fig.  214,  to  support  it  in  the  horizontal 
p  >sition.  The  tin  plate  is  first  stretched  in  the  hands  by  the  two 
corners,  a,  c,  and  rubbed  over  the  former  diagonally,  to  bend  it  at 
every  part ;  this  is  repeated  across  the  other  diagonal  to  flatten  the 
plate ;  it  is  afterwards  folded  round  the  stick,  and  rubbed  forcibly 
down  with  the  hand,  as  at  d,  to  give  it  an  easy  bend  approaching 
to  the  required  curvature.  Should  the  vessel  require  a  bed  at  the 
upper  edge,  it  is  usually  made  by  the  swage  tool,  Fig.  212,  before 
the  plate  is  curled  up;  the  work  is  then  much  more  rigid,  and 
requires  additional  force  to  bend  it. 


Fig.  215  is  intended  to  explain  a  very  simple  and  useful  machine, 
first  employed  by  the  tinmen  for  rolling  up  the  cylinders  for  spring 
window-blinds,  the  sides  of  culinary  vessels  and  similar  wprks,  and 
now  also  by  the  boiler- makers,  and  others  for  the  strongest  plates. 
It  has  two  cylindrical  rollers,  a,  b,  and  d,  which  are  connected  by 
toothed  wheels  so  as  to  travel  in  opposite  directions,  thus  far  ex- 
actly the  same  as  a  pair  of  laminating  rollers  for  making  the  sheet 
metals ;  the  third  roller  c,  is  just  opposite  the  two,  and  is  free  to 
move  on  its  pivots,  as  it  is  unconnected  with  a,  b,  and  rf;  and  the 
third  roller  c,  is  capable  of  vertical  adjustment. 
19 


290  THE   PRACTICAL    METAL-Vv'ORKEE  S   ASSISTANT. 

When,  therefore,  the  metal  is  moved  along  by  the  carrying 
rollers  a  b,  and  d,  it  strikes  against  the  edge  of  the  bending  roller  c, 
and  is  curled  up  to  enable  it  to  pass  over  the  same ;  and  as  this 
bending  occurs  in  an  equal  degree  at  every  point  of  the  sheet  of 
metal,  it  assumes  a  circular  sweep,  the  radius  of  which  is  depen- 
dent on  the  place  of  c.  In  the  central  position,  the  sheet  would 
assume  the  circle  e,f,  g-  and  when  c  is  more  raised  as  to  the  upper 
position,  the  metal  would  follow  the  dotted  circle,  the  radius  of 
which  is  much  less ;  and  when  the  bending  roller  c,  is  placed  out 
of  level,  the  works  are  thrown  into  the  conical  form. 

Fig.  216  shows  the  application  of  the  bending  rollers  to  boiler 
plates ;  none  of  the  rollers  a,  b,  c,  touch  each  other,  and  b  is  under 
adjustment  for  different  curvatures. 

In  the  last  four  figures  the  same  principle  is  employed,  namely, 
the  application  of  three  forces  as  in  a  lever  of  the  first  order,  or  as 
in  bending  or  breaking  a  stick  across  the  knee.  The  school-boy's 
problem  of  "drawing  a  circle  through  three  given  points"  is 
thoroughly  exemplified  in  Fig.  216  and  in  215,  the  one  force  is  the 
grip  of  the  plate  on  the  line  of  centres  of  a,  b,  d ;  the  roller  c,  curls 
the  plate  partly  around  the  roller  a,  and  the  point  at  which  the 
plate  leaves  a  b,  may  be  called  the  second  force,  or  b ;  the  third  is 
the  point  of  contact  on  c. 

One  of  the  most  useful  applications  of  the  lending  machines,  is 
in  straightening  the  metals,  which  may  at  first  appear  to  be  a  mis- 
application of  words,  but  in  truth  by  the  depression  of  c,  to  about 
the  position  of  c',  it  only  bends  the  plate  for  the  moment,  just  to  the 
Umit  of  its  elasticity.  It  results  that  when  it  has  been  passed 
through  twice,  or  with  each  side  alternately  upwards,  the  elastic 
reaction  just  suffices  to  convert  the  figure  temporarily  given,  or 
that  of  the  arc  of  an  enormous  circle,  into  a  plane  or  true  surface ; 
and  as  this  is  done  without  any  blows,  which  produce  partial  con 
densation  at  such  spots,  the  plate  is  less  subject  to  after  changes 
than  if  it  had  been  hammered  flat ;  as  by  the  rollers,  every  part  of 
the  plate  is  bent  exactly  to  the  limit  of  its  permanent  elasticity.  In 
the  tinmen's  bending  rollers,  d,  c,  Fig.  215,  are  often  turned  with 
half  round  grooves,  to  receive  the  thickened  edge  which  contains 
the  wire  employed  to  stiffen  the  tops  of  the  vessels;  sometimes 
also  the  rollers  are  used  for  preparing  the  seam  to  contain  the  • 
wire.  Grooved-rollers  (similar  to  "those  shown  on  page  81)  are 
very  extensively  employed,  likewise,  in  other  works  in  the  arts  be- 
sides the  manufacture  of  iron,  to  which  they  are  there  more  imme- 
diately referred. 

The  use  of  the  plain  cylindrical  roller  at  h,  page  81,  is  so  simple 
as  to  be  immediately  apparent;  rollers  with  curvilinear  edges,  such 
as  at  i,  have  been  long  employed  for  bending  the  steel  and  brass 
'plates  for  fenders ;  similar  rollers  on  a  smaller  scale  and  of  numer- 
ous patterns,  many  of  them  chased  and  ornamented,  are  used  in 
'making  jewelry,  as  for  producing  mouldings,  beadings,  and  matted, 
checkered  or  other  works 


WORKS   IX   SHEET    METAL. 


291 


IMPROVED  MACHINE  FOR  EOLLING  UP  SHEET  METAL  PIPE. — 
This  Machine  is  the  invention  of  Mr.  William  Ostrander,  of  New 
York,  and  is  patented  by  Ostrander  and  Webster.  It  consists  of 
three  rollers,  L  M  B  (the  same  as  ordinary  stovepipe  rollers) ;  J  is 
an  independent  pinion  which  mashes  in  the  smaller  ones  fastened 
to  the  rollers,  L  and  M,  which  gives  them  both  the  same  line  of 
motion ;  the  roller,  B,  is  raised  or  lowered  by  the  treadle,  G,  in 
connection  with  F  F,  upon  which  rest  the  boxes  of  B.  D  D  are 
set  screws  to  adjust  the  height  and  pressure  of  B;  I  is  a  set  screw, 

Fig.  217. 


E 


which  raises  or  lowers  M,  which  regulates  the  space  between  L,  M, 
and  B.  K  is  a  mandril  constructed  of  wood,  upon  which  the  pipe 
is  formed;  it  is  covered  with  the  same  material  that  is  desireftto 
be  rolled  or  formed  up  by  the  machine,  the  seam  or  joint  left  un- 
soldered, in  which  the  sheet  C  is  placed,  and  there  held  while  being 
formed  between  the  three  rollers.  E  is  the  pulley  and  belt;  A 
is  the  bench;  H  is  the  weight  which  is  used  only  when  the  machine 
is  worked  by  a  crank.  The  operation  by  steam  is  83  follows :  the 


292 


THE  PRACTICAL  METAL-WORKER'S   ASSISTANT. 


rollers,  L  and  M,  are  in  constant  motion,  the  mandril,  K,  is  taken 
out  from  the  three  rollers,  and  the  edge  of  the  sheet,  ^C,  to  be 
formed,  is  slipped  between  the  mandril  and  its  covering ;  it  is  then 
laid  in  the  space  it  occupies  as  represented  in  the  engraving ;  the 
foot  is  applied  to  G,  which  raises  the  roller,  B,  until  the  mandril, 
K,  is  brought  in  contact  with  L  and  M ;  the  three  rollers,  together 
with  the  mandril,  are  revolved,  and  the  sheet  C,  is  drawn  in  and 
formed  closely  about  the  mandril ;  the  foot  is  then  removed  from 
G,  which  allows  the  roller,  B,  to  drop  down,  and  permits  the  man- 
dril, K,  to  be  taken  out  and  the  newly-formed  pipe  to  be  slipped 
off,  whose  edge,  in  nearly  every  instance,  will  be  "laid"  close' 
enough  for  soldering :  should  the  metal  be  so  stiff  and  hard  as  to 
prevent  its  edge  being  laid  in  the  first  rolling,  it  will  be  perfectly 
so  when  rolled  a  second  time  on  the  bare  wooden  mandril.  This 
roller  is  capable  of  forming  from  three  to  five  thousand  feet  of  pipe 
per  10  hours,  in  20  inch  joints,  by  a  boy.  It  does  not  require  the 
use  of  mallets  to  lay  the  edges.  It  can  be  made  as  long  as  any 
sheet  of  metal  requires,  inasmuch  as  the  rollers  can  be  braced  from 
the  outside  without  being  interfered  with.  It  can  be  used  in  the 
old  way  for  stovepipe,  etc.,  by  removing  the  pinion,  J,  up  out  of 
the  way,  and  bringing  the  rollers,  L  M,  close  together. 

This  machine  is  now  in  practical  use  by  Woolcock  and  Ostran- 
der,  No.  57  Ann  Street,  N.  Y.,  who  make  large  quantities  of  speak- 
ing and  other  pipes  with  it. 

ANGLE  AND  SURFACE  JOINTS. — The  next  steps  to  be  considered, 
appear  to  be  the  methods  of  uniting  the  edges  of  the  vessels  after 
they  have  been  cut  and  bent  to  meet'  in  angles,  curves,  or  plane 
surfaces.  The  principal  modes  of  accomplishing  this  are  repre- 
sented in  Figs.  218  to  240,  which  are  grouped  together  for  the 
convenience  of  comparison. 

Figs.  218  and  219  are  for  the  thinnest  metals,  such  as  tin,  which 
require  a  film  of  soft-solder  on  one  or  other  side.  Sheet-lead  is 
similarly  joined,  and  both  are  usually  soldered  from  within. 


Figs.  218    219    220    221    222    223    224    225     226     227    228     229. 


Figs.  220  and  221  are  the  mitre  and  Jwft-joints  used  for  thicker 
metals  with  hard  solders.  Sometimes  221  is  dovetailed  together, 
the  edges  being  filled  to  correspond  coarsely  ;  they  are  also  partly 
riveted  before  being  soldered  from  within.  These  joints  are  very 
weak  when  united  with  soft  solder. 

Fig.  222  is  the  Zap-joint ;  the  metal  is  creased  over  the  hatchet 


WORKS   IX   SHEET   METAL.  293 

stake.  Tin-plate  requires  an  external  layer  of  solder;  spelter 
solder  runs  through  the  crevice,  and  need  not  project. 

Fig.  223  is  folded  by  means  of  the  hatchet-stake,  the  two  are 
then  hammered  together,  but  require  a  film  of  solder  to  prevent 
them  from  sliding  asunder. 

Fig.  224  is  the  folded  angle-joint,  used  for  fire-proof  deed  boxes, 
and  other  strong  works  in  which  solder  would  be  inadmissible.  It 
is  common  in  tin  and  copper  works,  but  less  so  in  iron  and  zinc, 
which  do  not  bend  so  readily. 

Fig.  225  is  a  riveted  joint,  which  is  very  commonly  used  in 
strong  iron  plate  and  copper  works,  as  in  boilers,  etc. ;  generally 
'  a  rivet  is  inserted  at  each  end,  then  the  other  holes  are  punched 
through  the  two  thicknesses  with  the  punch  210,  on  a  block  of 
lead.  The  head  of  the  rivet  is  put  within,  the  metal  is  flattened 
aroujid  it,  by  .placing  the  small  hole  of  the  riveting  set  211  over 
the  pin  of  the  rivet,  and  giving  a  blow ;  the  rivet  is  then  clinched, 
and  it  is  finished  to  a  circular  form  by  the  concave  hollow-  in 
another  riveting  set.  When  the  works  cannot  be  laid  upon  an 
anvil  or  stake,  a  heavy  hammer  is  held  against  the  head  of  the 
rivet  to  receive  the  blow ;  in  larger  works  the  holes  are  all  punched 
before  riveting,  and  the  heads  are  left  from  the  hammer. 

Figs.  226  and  227  ;  the  plates  a  a,  are  punched  with  long  mor- 
tises, then  b  b,  are  formed  into  tenons,  which  are  inserted  and 
riveted ;  but  in  227  the  tenons  have  transverse  keys  to  enable  the 
parts  to  be  separated. 

Fig.  228,  the  one  plate  makes  a  butt-joint  with  the  other,  and  is 
fixed  by  L  formed  rivets  or  screw-bolts  #;  the  short  ends  are 
generally  riveted  to  the  one  plate,  even  when  screwed  nuts  are 
used.  This  mode  is  very  common  for  cast-iron  plates,  as  in  stove 
work. 

Fig.  229  is  the  mode  universally  adopted  for  very  strong  ves- 
sels, as  for  steam-boilers,  in  which  the  detached  wrought-iron 
plates  are  connected  by  angle-iron,  rolled  expressly  for  the  pur- 
pose, (see  /,  Fig.  27,  p.  81).  The  rivet  holes  are  punched  in  all  the 
four  edges,  by  powerful  punching  engines  furnished  with  travel- 
ing stages  and  racks,  which  insure  the  holes  being  in  line,  and 
equidistant,  so  that  the  several  parts  when  brought  together  may 
exactly  correspond.  The  rivet  r,  which  may  be  compared  to  a 
short  stout  nail  is  made  red-hot,  and  handed  by  a  boy  to  the  man 
within  the  boiler,  who  drives  it  in  the  hole ;  he  then  holds  a  heavy 
hammer  against  its  head,  whilst  two  men  quickly  clench  or  burr 
it  up  from  without :  between  the  hammering,  and  the  contracting 
of  the  metal  in  cooling,  the  edges  are  brought  together  into  most 
intimate  and  powerful  contact.  Bolts  and  nuts  6,  may  be  used  to 
allow  the  removal  of  any  part,  as  the  man-hole  of  the  boiler. 

For  the  curved  parts  of  the  boilers,  the  angle  iron  is  bent  into 
corresponding  sweeps,  and  for  the  corners  of  square  boilers,  the 
angle  iron  is  welded  together  to  form  the  three  tails  for  the  re- 
spective angles  or  edges  which  constitute  the  solid  corner :  this 
when  well  done,  is  no  mean  specimen  of  welding. 


294 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 


It  frequently  happens  that  several  plates  are  required  to  be 
joined  together  to  extend  their  dimensions,  or  that  the  edges  of 
one  plate  are  united  as  in  forming  a  tube  ;  these  joints  are  arranged 
in  the  figures  230  to  240,  similarly  to  those  for  angles  previously 
shown,  from  which  they  differ  in  several  respects. 

Fig.  230  is  the  Zap-joint,  employed  with  solder  .for  tin  plates, 
sheet  lead,  etc.,  and  for  tubes  bent  up  in  these  materials. 

Fig.  231,  the  butt-joint,  is  used  for  plates  and  small  tubes  of  the 
various  metals  ;  united  with  the  hard  solders  they  are  moderately 
strong,  but  with  tin  solder  the  junctions  are  very  weak  from  the 
limited  measures  of  the  surfaces. 

Fig.  232  is  the  cramp  -joint :  the  edges 
are  thinned  with  the  hammer,  the  one  is 
left  plain,  the  other  is  notched  obliquely 
with  shears,  from  one-eighth  to  three- 
eighths  of  an  inch  deep ;  each  alternate 
cramp  is  bent  up,  the  others  down  for 
the  insertion  of  the  plain  edge ;  they  are 
next  hammered  together  and  brazed, 
after  which  they  may  be  made  nearly 
flat  by  the  hammer,  and  quite  so  by  the 
file.  The  cramp-joint  is  used  for  thin 
works  requiring  strength,  and  amongst 
numerous  others  for  the  parts  of  musical 
instruments.  Sometimes  also  230  is  fea- 
ther-edged; this  improves  it,  but  it  is 
still  inferior  to  the  cramp -joint  in 
strength. 

Fig.  233  is  the  lap-joint  without  sold- 
er, for  tin,  copper,  iron,  etc. ;  it  is  set 
down  flat  with  a  seam-set,  Fig.  209,  and 
used  for  smoke-pipes,  and  numerous 
works  not  required  to  be  steam  or  water- 
tight. 

Fig.  234  is  used  for  zinc  works  and 
others ;  it  saves  the  double  bend  of  233. 
Fig.  235  is  the  roll-joint  employed  for 
lead  roofs,  the  metal  is  folded  over  a 
wooden  rib,  and  requires  no  solder ;  the  water  will  not  pass  through 
this  joint  until  it  exceeds  the  elevation  of  the  wood.  The  roll- 
joint  is  less  bent  when  used  for  zinc,  as  that  material  is  rather 
brittle  ;  the  laps  merely  extend  up  the  straight  sides  of  the  wooden 
roll,  and  their  edges  are  covered  by  a  half-round  strip  of  zinc 
nailed  to  the  wood. 

Fig.  236  is  a  hollow  crease  used  for  vessels  and  chambers  for 
making  sulphuric  acid  ;  the  metal  is  scraped  perfectly  clean,  filled 
with  lead  heated  nearly  to  redness,  and  the  whole  are  united  by 
burning,  with  an  iron  heated  also  to  redness.  Solder  which  con- 
tains tin  would  be  acted  upon  by  the  acid,  whereas  until  the  acid 


238 


239 


240 


WORKS   IX   SHEET   METAL.  295 

is  very  concentrated,  the  lead  is  not  injured ;  this  method  is  how- 
ever now  superseded  by  the  mode  of  autogenous  soldering.  The 
concentration  of  sulphuric  acid  and  some  other  chemical  prepara- 
tions, is  performed  in  vessels  made  of  platinum. 

Figs.  237  and  238  are  very  commonly  employed  either  with 
rivets  or  screw-bolts ;  the  latter  joint  is  common  in  boilers,  both 
of  copper  and  iron,  and  also  in  tubes ;  copper  works  are  frequently 
tinned  all  over  the  rivets  and  joints,  to  stop  any  minute  fissures. 
Fig.  237  is  the  flange-joint  for  pipes. 

Fig.  239,  with  rivets,  is  the  common  mode  of  uniting  plates  of 
marine  boilers,  and  other  works  required  to  be  flush  externally. 

Fig.  240  is  a  similar  mode,  used  of  late  years  for  constructing  the 
largest  iron  steam-ships ;  the  ribs  of  the  vessels  are  made  of  T  iron, 
varying  from  about  four  to  eight  inches  wide,  which  is  bent  to  the 
curve  by  the  employment  of  very  large  surface-plates  cast  full  of 
holes,  upon  which  the  wood  model  of  the  rib  is  laid  down,  and  a 
chalk  mark  is  made  around  its  edge.  Dogs  or  pins  are  wedged  at 
short  intervals  in  all  those  holes  which  intersect  the  curve ;  the  rib, 
heated  to  redness  in  a  reverberatory  furnace,  is  wedged  fast  at  one 
end,  and  bent  round  the  pins  by  sets  and  sledge-hammers,  and  as 
it  grows  or  yields  to  the  curve,  every  part  is  secured  by  wedges 
until  the  whole  is  completed. 

The  following  method  of  constructing  metallic  boats,  invented  by 
Mr.  Francis,  of  the  Novelty  Works,  New  York,  is  taken  from  Har- 
per's New  Monthly  Magazine. 

In  many  cases  of  distress  and  disaster  befalling  ships  on  the 
coast,  it  is  not  necessary  to  use  the  car,  the  state  of  the  sea  being 
such  that  it  is  possible  to  go  out  in  a  boat,  to  furnish  the  necessary 
succor.  .  The  boats,  however,  which  are  destined  to  this  service 
must  be  of  a  peculiar  construction,  for  no  ordinary  boat  can  live  a 
moment  in  the  surf  which  rolls  in,  in  storms,  upon  shelving  or 
rocky  shores.  A  great  many  different  modes  have  been  adopted 
for  the  construction  of  surf-boats,  each  liable  to  its  own  peculiar 
objections.  The  principle  on  which  Mr.  Francis  relies  in  his  life 
and  surf-boats,  is  to  give  them  an  extreme  lightness  and  buoyancy, 
so  as  to  keep  them  always  upon  the  top  of  the  sea.  Formerly  it 
was  expected  that  a  boat  in  such  a  service,  must  necessarily  take 
in  great  quantities  of  water,  and  the  object  of  all  the  contrivances 
for  securing  its  safety,  was  to  expel  the  water  after  it  was  admitted. 
In  the  plan  now  adopted  the  design  is  to  exclude  the  water  alto- 
gether, by  making  the  structure  so  light  and  forming  it  on  such  a 
model  that  it  shall  always  rise  above  the  wave,  and  thus  glide 
safely  over  it  This  result  is  obtained  partly  by  means  of  the  model 
of  the  boat,  and  partly  by  the  lightness  of  the  material  of  which  it 
is  composed.  The  reader  may  perhaps  be  surprised  to  hear,  after 
this,  that  the  material  is  iron. 

Iron — or  copper,  which  in  this  respect  possesses  the  same  proper- 
ties as  iron — though  absolutely  heavier  than  wood,  is,  in  fact,  much 
lighter  as  a  material  for  the  construction  of  receptacles  of  all  kinds. 


296 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


en  account  of  its  great  strength  and  tenacity,  which  allows  of  its 
being  used  in  plates  so  thin  that  the  quantity  of  the  material  em- 
ployed is  diminished  much  more  than  the  specific  gravity  is  in- 
creased by  using  the  metal.  There  has  been,  however,  hitherto  a 
great  practical  difficulty  in  the  way  of  using  iron  for  such  a  pur- 
pose, namely,  that  of  giving  to  these  metal  plates  a  sufficient  stiff- 
ness. A  sheet  of  tin,  for  example,  though  stronger  than  a  board, 
that  is,  requiring  a  greater  force  to  break  or  rupture  it,  is  still  very 
flexible,  while  the  board  is  stiff.  In  other  words,  in  the  case  of  a 
thin  plate  of  metal,  the  parts  yield  readily  to  any  slight  force,  so  far 
as  to  bend  under  the  pressure,  but  it  requires  a  very  great  force  to 
separate  them  entirely ;  whereas  in  the  case  of  wood,  the  slight  force 
is  at  first  resisted,  but  on  a  moderate  increase  of  it,  the  structure 
breaks  down  altogether.  The  great  thing  to  be  desired  therefore, 
in  a  material  for  the  construction  of  boats,  is  to  secure  the  stiffness 
of  wood  in  conjunction  with  the  thinness  and  tenacity  of  iron. 
This  object  is  attained  in  the  manufacture  of  Mr.  Francis's  boats  by 
plaiting  or  corrugating  the  sheets  of  metal  of  which  the  sides  of  the 
boat  are  to  be  made.  A  familiar  illustration  of  the  principle  on 
which  this  stiffening  is  effected  is  furnished  by  the  common  table 
waiter,  which  is  made  usually,  of  a  thin  plate  of  tinned  iron, 
stiffened  by  being  turned  up  at  the  edges  all  around — the  upturned 
part  serving  also  -at  the  same  time  the  purpose  of  forming  a 
margin. 

The  platings  or  corrugations  of  the  metal  in  these  iron  boats 
pass  along  the  sheets,  in  lines,  instead  of  being,  as  in  the  case  of  the 
waiter,  confined  to  the  margin.  The  idea  of  thus  corrugating  or 

Fig.  241. 


WORKS   IX   SHEET   METAL.  297 

plaiting  the  metal  was  a  very  simple  one ;  the  main  difficulty  in' 
the  invention  came,  after  getting  the  idea,  in  devising  the  ways 
and  means  by  which  such  a  corrugation  could  be  made.  It  is  a 
curious  circumstance  in  the  history  of  modern  inventions  that  it 
often  requires  .much  more  ingenuity  and  effort  to  contrive  a  way 
to  make  the  article  when  invented,  than  it  did  to  invent  the  article 
itself.  It  was,  for  instance,  much  easier,  doubtless,  to  invent  pins, 
than,  to  invent  the  machinery  for  making  pins. 

The  machine  for  making  the  corrugations  in  the  sides  of  these 
metallic  boats  consists  of  a  hydraulic  press  and  a  set  of  enormous 
dies.  These  dies  are  grooved  to  fit  each  other,  and  shut  together ; 
and  the  plate  of  iron  which  is  to  be  corrugated  being  placed  be- 
tween them,  is  pressed  into  the  requisite  form,  with  all  the  force 
of  the  hydraulic  piston — the  greatest  force,  altogether,  that  is  ever 
employed  in  the  service  of  man. 

The  machinery  referred  to  will  be  easily  understood  by  the  above 
engraving.  On  the  left  are  the  pumps,  worked,  as  represented  in 
the  engraving,  by  two  men,  though  four  or  more  are  often  required. 
By  alternately  raising  and  depressing  the  break  or  handle,  they 
work  two  small  but  very  solid  pistons  which  play  within  cylinders 
of  corresponding  bore,  in  the  manner  of  any  common  forcing-pump. 

By  means  of  these  pistons  the  water  is  driven  in  small  quantities, 
but  with  prodigious  force,  along  through  the  horizontal  tube  seen 
passing  across,  in  the  middle  of  the  picture,  from  the  forcing-pump 
to  the  great  cylinders  on  the  right  hand.  Here  the  water  presses 
upward  upon  the  under  surface  of  pistons  working  within  the  great 
cylinders,  with  a  force  proportional  to  the  ratio  of  those  pistons 
compared  with  that  of  one  of  the  pistons  in  the  pump.  Now  the 
piston  in  the  force-pump  is  about  one  inch  in  diameter.  Those  in 
the  great  cylinders  are  about  twelve  inches  in  diameter,  and  as  there 
are  four  of  the  great  cylinders  the  ratio  is  as  1  to  576.  Areas 
being  as  the  squares  of  homologous  lines,  the  ratio  would  be,  mathe- 
matically expressed,  I1  :  4x  12'= 1  :  4x  144=1  :  576.  This  is  a 
great  multiplication,  and  it  is  found  that  the  force  which  the  men 
can  exert  upon  the  piston  within  the  small  cylinder,  by  the  aid  of 
the  long  lever  with  which  they  work  it,  is  so  great,  that  when  multi- 
plied by  576,  as  it  is  by  being  expanded  over  the  surface  of  the 
large  pistons,  an  upward  pressure  results  of  about  eight  hundred 
tons.  This  is  a  force  ten  times  as  great  in  intensity  as  that  exerted 
1ry  steam  in  the  most  powerful  sea-going  engines.  It  would  be 
sufficient  to  lift  a  block  of  granite  five  or  six  feet  square  at  the  base, 
and  as  high  as  the  Bunker  Hill  Monument. 

Superior,  however,  as  this  force  is,  in  one  point  of  view,  to  that 
of  steam,  it  is  very  inferior  to  it  in  other  respects.  It  is  great,  so 
to  speak,  in  intensity,  but  it  is  very  small  in  extent  and  amount.  It 
is  capable  indeed  of  lifting  a  very  great  weight,  but  it  can  raise  it 
only  an  exceedingly  little  way.  Were  the  force  of  such  an  engine 
to  be  brought  into  action  beneath  such  a  block  of  granite  as  we 
have  described,  the  enormous  burden  would  rise,  but  it  would  rise 


298  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

by  a  motion  almost  inconceivably  slow,  and  after  going  up  perhaps 
as  high  as  the  thickness  of  a  sheet  of  paper,  the  force  would  be 
spent,  and  no  further  effect  would  be  produced  without  a  new  ex- 
ertion of  the  motive  power.  In  other  words,  the  whole  amount  of 
the  force  of  a  hydraulic  engine,  vastly  concentrated  as  it  is,  arid 
irresistible,  within  the  narrow  limits  within  which  it  works,  is  but 
the  force  of  four  or  five  men  after  all ;  while  the  power  of  the 
engines  of  a  Collins'  steamer  is  equal  to  that  of  four  or  five  thousand 
men.  The  stearn-engine  can  do  an  abundance  of  great  work  ;  while, 
on  the  other  hand,  what  the  hydraulic  press  can  do  is  very  little  in 
amount,  and  only  great  in  view  of  its  extremely  concentrated 
intensity. 

Hydraulic  presses,  before  the  introduction  of  D.  Dick's  anti-fric- 
tion press,  were  often  used,  in  such  cases  and  for  such  purposes  as 
require  a  great  force  within  very  narrow  limits.  The  indentations 
made  by  the  type  in  printing  the  pages  of  Harper's  Magazine,  are 
taken  out,  and  the  sheet  rendered  smooth  again,  by  hydraulic 
presses  exerting  a  force  of  twelve  hundred  tons.  This  would  make 
it  necessary  for  us  to  carry  up  our  imaginary  block  of  granite  a 
hundred  feet  higher  than  the  Bunker  Hill  Monument  to  get  a  load 
for  them. 

There  are  nine  of  these  presses  in  the  printing-rooms  of  Harper 
and  Brothers,  alPconstantly  employed  in  smoothing  sheets  of  paper 
after  the  printing.  The  sheets  of  paper  to  be  pressed  are  placed 
between  sheets  of  very  smooth  and  thin,  but  hard  pasteboard,  until 
a  pile  is  made  several  feet  high,  and  containing  sometimes  two 
thousand  sheets  of  paper,  and  then  the  hydraulic  pressure  is  applied. 
These  presses  cost,  each,  from  twelve  to  fifteen  hundred  dollars. 

In  Mr.  Francis's  presses,  the  dies  between  which  the  sheet  of  iron 
or  copper  are  pressed,  are  directly  above  the  four  cylinders  which 
we  have  described,  as  will  be  seen  by  referring  once  more  to  the 
drawing.  The  upper  die  is  fixed— being  firmly  attached  to  the  top 
of  the  frame,  and  held  securely  down  by  the  rows  of  iron  pillars  on 
the  two  sides,  and  by  the  massive  iron  caps,  called  platens,  which 
may  be  seen  passing  across  at  the  top,  from  pillar  to  pillar.  These 
caps  are  held  by  large  iron  nuts  which  are  screwed  down  over  the 
ends  of  the  pillars  above.  The  lower  die  is  movable.  It  is  attached 
by  massive  iron  work  to  the  ends  of  the  piston-rods,  and  of  course 
it  rises  when  the  pistons  are  driven  upward  by  the  pressure  of  the 
water.  The  plate  of  metal,  when  the  dies  approach  each  other,  is 
bent  and  drawn  into  the  intended  shape  by  the  force  of  the  pressure, 
receiving  not  only  the  corrugations  which  are  designed  to  stiffen 
it,  but  also  the  general  shaping  necessary,  in  respect  to  swell  and 
curvature,  to  give  it  the  proper  form  for  the  side,  or  the  portion  of 
a  side,  of  a  boat. 

It  is  obviously  necessary  that  the  dies  should  fit  each  other  in  a 
very  accurate  manner,  so  as  to  compress  the  iron  equally  in  every 
part.  To  make  them  fit  thus  exactly,  massive  as  they  are  in  mag- 
nitude, and  irregular  in  form,  is  a  work  of  immense  labor.  They 


WORKS   IX   SHEET   METAL.  299 

arc  first  cast  as  nearly  as  possible  to  the  form  intended,  but  as  such 
castings  always  warp  more  or  less  in  cooling,  there  is  a  great  deal 
of  fitting  afterwards  required,  to  make  them  come  rightly  together. 
This  could  easily  be  done  by  machinery  if  the  surfaces  were  square 
or  cylindrical,  or  of  any  other  mathematical  form  to  which  the 
working  of  machinery  could  be  adapted.  But  the  curved  and 
winding  surfaces  which  form  the  hull  of  a  boat  or  vessel,  smooth 
and  flowing  as  they  are,  and  controlled,  too,  by  established  and 
well-known  laws,  bid  defiance  to  all  the  attempts  of  mere  mechanical 
motion  to  follow  them.  The  superfluous  iron,  therefore,  of  these 
dies,  must  all  be  cut  away  by  chisels  driven  by  a  hammer  held  in 
the  hand ;  and  so  great  is  the  labor  required  to  fit  and  smooth  and 
polish  them,  that  a  pair  of  them  costs  several  thousand  dollars  before 
they  are  completed  and  ready  to  fulfil  their  function. 

The  superiority  of  metallic  boats  whether  of  copper  or  iron, 
made  in  the  manner  above  described,  over  those  of  any  other  con- 
struction, is  growing  every  year  more  and  more  apparent.  They 
are  more  light  and  more  easily  managed,  they  require  far  less 
repair  from  year  to  year,  and  are  very  much  longer  lived.  When 
iron  is  used  for  this  purpose,  a  preparation  is  employed  that  is 
called  galvanized  iron.  This  manufacture  consists  of  plates  of  iron 
of  the  requisite  thickness,  coated  on  each  side,  first  with  tin,  and 
then  with  zinc ;  the  tin  being  used  simply  as  a  sblder,  to  unite  the 
other  metals.  The  plate  presents,  therefore,  to  the  water,  only  a 
surface  of  zinc,  which  resists  all  action,  so  that  the  boats  thus  made 
are  subject  to  no  species  of  decay.  They  can  be  injured  or  de- 
stroyed only  by  violence,  and  even  violence  acts  at  a  very  great 
disadvantage  in  attacking  them.  The  stroke  of  a  shot,  or  a  con- 
cussion of  any  kind  that  would  split  or  shiver  a  wooden  boat  so  as 
to  damage  it  past  repair,  would  only  indent,  or  at  most  perforate, 
an  iron  one.  And  a  perforation  even,  when  made,  is  very  easily 
repaired,  even  by  the  navigators  themselves,  under  circumstances 
however  unfavorable.  With  a  smooth  and  heavy  stone  placed 
upon  the  outside  for  an  anvil,  and  another  used  on  the  inside  as  a 
hammer,  the  protrusion  is  easily  beaten  down,  the  opening  is 
closed,  the  continuity  of  surface  is  restored,  and  the  damaged  boat 
,  becomes,  excepting,  perhaps,  in  the  imagination  of  the  navigator, 
as  good  once  more  as  ever. 

Metallic  boats  of  this  character  were  employed  by  the  party  under 
Lieut.  Lynch,  of  the  U.  S.  Navy,  now  a  traitor  to  his  country,  in 
making  their  voyage  to  the  Dead  Sea.  The  navigation  of  the  stream 
was  difficult  and  perilous  in  the  highest  degree.  The  boats  were 
subject  to  the  severest  possible  tests  and  trials.  They  were  impelled 
against  rocks,  they  were  dragged  over  shoals,  they  were  swept 
down  cataracts  and  cascades.  There  was  one  wooden  boat  in  the 
little  squadron;  but  this  was  soon  so  strained  and  battered  that  it 
could  no  longer  be  kept  afloat,  and  it  was  abandoned.  The  metallic 
boats,  however,  lived  through  the  whole,  and  finally  floated  in  peace 
on  the  heavy  waters  of  the  Dead  Sea,  in  nearly  as  good  a  condition 
as  when  they  first  came  from  Mr.  Francis's  dies. 


300  THE   PEACTICAL   METAL-WORKER'S  ASSISTANT. 

The  seams  of  a  metallic  boat  will  never  open  by  exposure  to  the 
sun  and  rain,  when  lying  long  upon  the  deck  of  a  ship,  or  hauled  up 
upon  a  shore.  Nor  will  such  boats  burn.  If  a  ship  take  fire  at 
sea.  the  boats  if  of  iron,  can  never  be  injured  by  the  conilagation. 
Nor  can  they  be  sunk.  For  they  are  provided  with  air  chambers 
in  various  parts,  each  separate  from  the  others,  so  that  if  the  boat 
were  bruised  and  jammed  by  violent  concussions,  up  to  her  utmost 
capacity  of  receiving  injury,  the  shapeless  mass  would  still  float 
upon  the  sea,  and  hold  up  with  unconquerable  buoyancy  as  many 
as  could  cling  to  her. 

The  principle  on  which  these  life-boats  are  made  is  found  equally 
advantageous  in  its  application  to  boats  intended  for  other  pur- 
poses. For  a  gentleman's  pleasure-grounds,  for  example,  how 
great  the  convenience  of  having  a  boat  which  is  always  stanch  and 
tight — which  no  exposure  to  the  sun  can  make  leaky,  which  no 
wet  can  rot,  and  no  neglect  impair.  And  so  in  all  other  cases 
where  boats  are  required  for  situations  or  used  where  they  will  be 
exposed  to  hard  usage  of  any  kind,  whether  from  natural  causes 
or  the  neglect  or  inattention  of  those  in  charge  of  them,  this  ma- 
terial seems  far  superior  to  any  other. 


CHAPTEE  XVII. 

WORKS  IN  SHEET  METAL,  MADE   BY  RAISING;  AND  THE  FLATTENING 
OF  THIN  PLATES  OF  METAL. 

CIRCULAR  WORKS  SPUN  IN  THE  LATHE. — The  former  examples 
have  only  called  into  action  so  small  an  amount  of  the  malleable 
or  gliding  property  of  the  metals,  that  all  the  forms  referred  to 
could  be  produced  in  pasteboard,  a  material  nearly  incapable  of 
extension  or  compression.  The  raised  works  now  to  be  consid- 
ered, call  for  much  of  this  gliding  or  malleable  action  which  may 
be  compared  with  the  plastic  nature  of  clay  as  an  opposite  extreme. 
Thus  a  lump  of  clay  is  thrown  on  the  potter's  horizontal  lathe,  a 
touch  of  the  fingers  shapes  it  into  a  solid  round  lump,  the  potter 
thrusts  his  clenched  hand  into  the  Centre,  and  it  raises  in  form 
something  like  a  basin ;  by  applying  the  other  hand  outside  to 
prevent  the  material  from  spreading,  it  will  rise  as  an  irregular 
hollow  cylinder,  and  a  gentle  pressure  from  without,  and  a  sustain- 
ing pressure  from  within,  will  gather  up  or  contract  the  clay  into 
the  narrow  mouth  suited  to  a  bottle,  and  which  is  made  somewhat 
in  this  manner  almost  by  the  fingers  alone. 

A  similar  and  parallel  application,  due  to  the  malkability  of  the 
inetals,  and  one  which  also  requires  the  turning-lathe,  is  very  ex- 


WORKS   IX   SHEET   METAL. 


301 


tensively  practised :  namely,  the  art  of  "  spinning  or  burnishing  to 
form"  thin  circular  works  in  several  of  the  ductile  metals  and 
alloys,  as  for  teapots,  plated  candlesticks,  the  covers  of  cups  and 
vessels,  the  bell  mouths  of  musical  instruments,  and  numerous 
other  objects  required  in  great  numbers,  and  of  thin  metals.  Plated 
candlesticks  are  thus  formed  of  several  parts  soldered  together,  or 
retained  in  position. by  the  fittings  of  their  edges,  the  whole  being 
strengthened  by  a  central  wire,  and  by  filling  the  entire  cavity 
with  a  resinous  cement.  The  Figs.  242  and  243  are  intended  to 
show  the  mode  of  spinning  the  body  of  a  Britannia  metal  teapot 
from  one  unperforated  disk  of  metal. 

The  wooden  mould  or  chuck  a,  Fig.  242,  is  turned  to  the  form 
of  the  lower  part  of  the  teapot,  and  a  disk  of  metal  b,  is  pinched 
tight  between  the  flat  surfaces  of  a  and  c,  by  the  .fixed  centre  screw 
d  of  the  lathe,  so  that  a,  b,  and  c,  revolve  with  the  mandrel :  and 
now  by  means  of  a  burnisher  e,  which  is  rested  against  a  pin  in  the 
lathe  rest,  as  a  fulcrum,  and  applied  near  the  centre  of  the  metal ; 
and  a  wooden  stick  /,  held  on  the  opposite  side  to  support  the 
edge,  the  metal  is  rapidly  bent  or  swaged  through  the  successive 
forms  1,  2,  3,  to  4,  so  as  to  fit  close  against  the  curved  face  of  the 
block  and  to  extend  up  its  cylindrical  edge. 

The  mould  a  is  next  replaced  by  g,  Fig.  243,  a  plain  cylindrical 
block  of  the  diameter  of  the  intended  aperture.  One  of  various 


243. 


forms  of  burnishers  (h,  i,  some  bent,  others  T  form,  and  so  on,  the 
surfaces  of  which  are  slightly  greased)  are  used,  together  with  the 
hooked  stick  or  rubber/,  first  to  force  the  metal  inwards,  as  shown 
at  5,  6,  7,  and  also  to  curl  up  the  hollow  bead  which  stiffens  the 
mouth  of  the  finished  vessel,  9.  Sometimes  the  moulds  are  made 
of  the  entire  form  of  the  inside  of  the  work,  but  of  several  pieces, 
each  smaller  than-  the  mouth  ;  so  that  when  the  central  block  is 
first  removed  the  others  may  be  successively  taken  out  of  the 
finished  vessel,  like  the  parts  of  a  hat-block  or  of  a  boot-tree. 
It  is  of  importance  during  the  whole  process  to  keep  the  edge 


302 


THE    PRACTICAL   METAL- WORKER'S   ASSISTANT. 


Fig.  244. 


exactly  concentric  and  free  from  the  slightest  notches,  for  which 
purpose  it  is  occasionally  touched  with  the  turning  tool  during  the 
process  of  spinning.  The  operation  is  very  pretty  and  expeditious, 
and  resembles  the  manipulation  of  the  potter  who  forms  a  bottle 
or  vase  with  a  close  mouth  in  a  manner  completely  analogous, 
although  the  yielding  nature  of  his  material  requires  the  fingers 
alone,  and  neither  the  mould,  stick,  nor  burnisher. 

The  lenses  of  optical  instruments 
are  often  fixed  in  their  cells  by  simi- 
lar means;  a,  Fig.  244,  shows  in 
excess  the  form  of  the  metal  when 

Jjk      turned,  and   b  the   thin  edge  when 
EL     curled  over  the  glass  by  means  of  a 
burnisher  applied  whilst  the  ring  re- 
volves in  the  lathe. 

Much  of  the  cheap  Birmingham  jewelry  is  also  spun  in  the 
lathe,  but  in  a  different  manner.  For  instance,  to  make  such  an 
object  as  the  ring  represented  black  in  Fig.  245,  a  steel  mandrel  is 
turned  upon  a  lathe  to  the  same  form  as  the  ring,  but  less  in 
diameter.  The  metal  is  prepared  as  a  thin  tube,  it  is  soldered  and 
cut  into  short  pieces,  each  to  serve  for  one  ring,  and  these  are  spun 
into  shape  almost  in  an  instant,  between  the  arbor  and  the  milling 
tool  or  roller,  as  seen  in  the  front  view,  Fig.  246.  It  is  clear  that 
unless  the  arbor  were  smaller  than  the  work,  the  latter  from  being 


Fig.  245 


246. 


undercut  could  not  be  released.  Sometimes  only  one  broad  mill- 
ing tool  is  employed,  at  other  times  two  or  more  narrow  ones. 
This  process  is  most  distinctly  a  modification  of  two  rollers,  which 
travel  by  surface-contact  instead  of  by  toothed  wheels,  and  differs 
but  little  from  the  embossing  or  matting  rollers  employed  by  jewel- 
ers and  others  for  long  strips  instead  of  rings.  Extending  the 
same  application  to  the  milling-tool  upon  a  solid  body,  such  as 
milled  nut,  the  interior  metal  supplies  the  resistance  given  by  the 
arbor,  in  the  last  figure. 

WORKS  RAISED  BY  THE  HAMMER.— In  raising  the  metals  by 
the  hammer,  we  have  to  produce  similar  effects  to  those  in  the 
spinning  process ;  not  however  by  the  gradual  and  continued  pres- 
sure of  a  burnisher,  on  one  circle  at  a  time,  but  by  circles  of  blows, 


WORKS   IN   SHEET   METAL.  303 

applied  much  in  the  same  order,  and  as  far  as  possible  with  the 
same  regularity  of  effect. 

The  art  consists,  therefore,  of  two  principal  points.  First,  so  to 
proportion  the  original  size  and  thickness  of  the  metal  disks  that 
it  shall  exactly  suffice  for  the  production  of  the  required  object — 
neither  with  excess  of  metal,  which  would  have  to  be  cut  off  with 
shears  and  thrown  aside,  wasting  a  part  both  of  the  metal  and 
labor,  nor  with  deficiency  of  metal,  which  would  be  nearly  a  total 
loss.  Secondly,  that  the  work  shall  be  produced  with  the  smalkst 
possible  number  of  blows,  which  sometimes  tend  to  thin,  and  at  other 
times  to  thicken  the  metal ;  whereas  the  finished  works  should 
present  a  uniform  thickness  throughout,  and  which  is,  in  many 
cases,  just  that  of  the  original  metal  when  in  the  sheet. 

For  instance,  a  hollow  ball  six  inches  diameter  is  made  of  two 
circular  pieces  of  copper,  each  seven  and  a  half  inches  diameter. 
Now,  calling  the  original  circumference  of  the  disk  twenty-two  and 
a  half  inches,  this  line  eventually  becomes  contracted  to  eighteen 
inches,  or  the  circumference  of  the  ball, — although,  at  the  same 
time,  the  original  diameter  of  the  disk,  namely,  a  line  of  seven  and 
a  half  inches,  has  become  stretched  to  that  of  nine  inches  or  the 
girth  of  the  hemisphere. 

This  double  change  of  dimensions,  accomplished  by  the  mallea- 
bility or  gliding  of  the  metal,  occurs  in  a  still  more  striking  man- 
ner in  the  illustration  of  spinning  the  tea-pot,  in  which  the  disk, 
originally  about  one  foot  diameter,  becomes  contracted  to  two  or 
three  inches  only  at  the  mouth.  The  precise  nature  of  the  change 
is  seen  on  inspecting  Figs.  190  and  192  in  connection  with  the 
radiated  pieces  191  and  193  required  for  the  formation  of  such 
polygonal  vases,  when  bent  up  and  soldered  at  their  edges. 

The  same  vases  wrought  to  the  circular  figure  from  round  plates, 
either  by  spinning  or  by  the  hammer,  would  not  require  disks  of 
metal  so  large  as  the  boundary  circles  in  Figs.  191  and  193;  as 
the  pieces  between  the  rays  would  be  entirely  in  excess,  they 
would  cause  the  vessels  to  rise  beyond  their  intended  sizes,  and 
would  require  to  be  pared  off.  But  the  original  disks  for  making 
the  vases  should  be  of  about  the  diameters  of  the  inner  circles,  as 
then  the  pieces  d,  beyond  the  inner  circles,  would  be  nearly  equal 
to  the  spaces  e,  within  these  circles,  which  would  leave  the  vessel 
of  uniform  thickness  throughout,  and  without  deficiency  or  excess 
of  metal,  supposing  the  conversion  to  be  performed  with  mathe- 
matical truth. 

The  first  and  most  important  notion  to  be  conveyed  in  reference 
to  raising  works  with  the  hammer,  is  the  difference  between  those 
which  may  be  called  opposed,  or  solid  blows,  that  have  the  effect  of 
stretching  or  thinning  the  metal ;  and  those  which  may  be  called 
unopposed,  or  hollow  blows,  that  have  less  effect  in  thinning  than 
in  bending  the  metal ;  in  fact,  it  often  becomes  thickened  by  hollow 
blows,  as  will  be  shown. 

For  example,  the  hammer  in  Fig.  247  is  directly  opposed  to  the 


304 


THE   PRACTICAL   METAL-WOEKER'S  ASSISTANT. 


face  of  the  anvil,  or  meets  it  face  to  face,  and  would  be  said  to  give 
a  solid  blow;  one  which  would  not  jar  the  hand  grasping  the 
plate,  were  the  latter  ever  so  thick  or  rigid :  and  this  blow  would 
thin  the  metal  by  its  sudden  compression  between  two  hard  sur- 
faces, the  face  of  the  hammer  being  represented  at  /. 


The  hammer  m  Fig.  248  is  not  directly  opposed  to  the  anvil,  or 
rather  to  that  point  of  it  which  sustains  the  work,  consequently 
this  would  be  called  a  hollow  blow,  one  which  would  jar  the  hand 
were  the  plate  thick  and  rigid ;  and  it  would  bend  the  plate  partly 
to  the  form  of  the  supporting  edge,  by  a  similar  exhibition  of  the 
forces  a,  b,  c,  referred  to  in  the  diagrams,  Figs.  213  to  216 ;  not,  how- 
ever, by  the  quiet  pressure  therein  employed,  but  by  impact,  or  by 
driving  blows.  The  hand  situated  at  a,  Fig.  248,  would  be  insuffi- 
cient to  withstand  the  blows  of  the  hammer  at  c,  but  for  the  great 
distance  of  a  b,  compared  with  b  c,  and  the  thin  flexible  nature  of 
the  material. 

From  these  reasons  the  coppersmith  and  others  never  require 
tongs  for  holding  the  metal,  the  same  as  the  blacksmith,  except  at 
the  fire,  as  in  annealing  and  soldering ;  in  hammering  thin  works, 
a  constant  change  of  position  is  required,  and  which  can  be  in  no 
way  so  readily  accomplished  as  by  the  exquisite  mechanism  given 
us  by  nature,  the  unassisted  hand.  When,  however,  the  works  are 
too  rigid  or  too  small  to  be  thus  held,  the  anvil  is  made  to  supply 
the  two  points  a,  c,  as  in  Fig.  249,  and  the  blow  of  the  hammer  is 
directed  between  them. 

We  will  now  trace  the  effects  of  solid  and  hollow  blows  given 
partially  on  a  disk  of  metal  a  a,  Fig.  250,  supposed  to  be  twelve 
inches  diameter ;  first  within  a  central  circle  c  c,  of  three  inches 
diameter ;  and  then  around  the  margin  a  b,  to  the  width  of  three 
inches,  leaving  the  other  portions  untouched  in  each  case ;  the 
thickness  of  the  metal  is  greatly  exaggerated  to  facilitate  the 
explanation. 

The  solid  blows  within  the  circle  c  c,  would  thin  and  stretch  that 
part  of  the  metal,  and  make  it  of  greater  superficial  extent ;  but 
the  broad  band  of  metal  a  c,  would  prevent  it  from  expanding  be- 


WORKS   IX   SHEET    METAL. 


305 


C  6 


252 
253 


254 


255 


257 


yond  its  original  diameter,  and  therefore  the  blows  would  make  a 
central  concavity,  as  in  a  cymbal,  or  like  Fig.  251.  And  the  more 
blows  that  were  given;  either  inside  the  bulge  upon  a  flat  anvil,  or 
outside  the  bulge  upon  an  anvil  or  head  of  a  globular  form,  the 
more  would  the  metal  be  raised,  from  its  being  thinned  and  ex- 
tended ;  and  thus  it  might  be  thrown  into  the  shape  of  a  lofty 
cone  or  sugar-loaf.  , 

The  hollow  blows  given  within  the  same 
limited  circle  would  also  stretch  the  metal 
and  drive  it  into  the  hollow  tools  employed, 
such  as  Fig.  249  ;  thus  producing  the  same 
effect  as  in  251,  but  by  stretching  the  metal 
as  we  should  the  parchment  of  a  drum, 
by  the  pressure  of  the  hand  in  the  centre, 
or  by  a  blow  of  the  drum-stick. 

The  solid  blows  around  the  three-inch 
margin,  would  thin  the  metal  and  cause  it 
to  increase  externally  in  diameter;  but 
the  plate  would  only  continue  flat,  as  in 
Fig.  252,  if  every  part  of  the  ring  were 
stretched  proportionally  to  its  increased 
distance  from  its  first  position.  Were  the 
inner  edge  towards  b,  thinned  beyond  its 
due  amount,  its  expansion,  if  resisted  by 
the  strength  of  the  outer  ring  a,  would 
throw  part  of  the  work  into  a  curve,  and 
depress  the  metal,  not  as  in  the  cymbal, 
but  in  the  form  of  a  gutter  as  in  Fig.  253 ; 
it  would  however  more  probably  happen,  that  the  inner  edge  alone 
of  the  marginal  ring  would  be  expanded,  leaving  the  outer  edge 
undisturbed,  and  producing  the  coned  figure,  254. 

The  hollow  blows  given  around  the  edge,  as  in  Fig.  248,  would 
have  the  eftect  of  curling  up  or  raising  the  edge,  first  as  a  saucer 
255,  and  then  into  a  cylindrical  form  256 ;  provided  that  by  the 
skilful  management  of  the  hammering,  the  metal  could  be  made  to 
slide  upon  itself  without  puckering,  so  as  to  contract  the  original 
boundary  circle  of  the  disk  or  twelve  inches,  into  six  inches,  or 
the  measure  of  the  edge  of  the  cylinder  resulting  from  the  drawing 
in  of  the  three-inch  margin. 

In  this  process  the  metal  would  become  proportionally  thickened 
at  the  upper  edge,  because  each  little  piece  of  the  great  circle,  Fig. 
257,  when  compressed  into  a  circle  of  half  the  diameter,  would 
only  occupy  half  its  original  length,  as  it  could  not  be  altogether 
lost;  and  the  metal  would  therefore  increase  in  thickness  in  a  pro- 
portional degree.  The  remainder  of  the  circle  serves  for  the  time 
as  effectually  to  compress  the  metal  in  the  direction  of  the  tangent, 
as  if  the  radii  were  the  sides  of  an  unyielding  angular  groove 
dotted  in  Fig.  257 :  this  contraction  produces  in  fact  the  same  effect 
as  the  jumping  or  upsetting  by  endlong  blows  in  smith's-work. 
20 


306  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

Theoretically,  the  thickness  of  the  upper  edge  of  the  cylinder 
would  be  doubled,  and  the  lower  edge  would  retain  its  original 
thickness,  as  in  256 ;  whereas  in  extending' the  margin  of  the  disk 
by  solid  blows  as  in  Fig.  252,  the  thinned  edge  would  be  found  to 
taper  away,  also  in  a  straight  line,  from  the  full  thickness  even  to  a 
feather  edge  if  sufficiently  continued,  but  neither  of  these  cases 
would  be  admissible,  as  the  general  object  is  to  retain  a  uniform 
substance. 

In  equalizing  the  thickness  of  the  cylindrical  tube,  Fig.  256,  the 
solid  blows  would  thin  the  metal,  but  at  the  same  time  threw  it 
into  a  larger  circle ,  it  would  then  require  to  be  again  driven  in- 
wards, which  would  again  slightly  thicken  it.  So  that  in  reducing 
the  metal  to  uniformity,  two  distinct  and  opposite  actions  are  going 
on;  and  upon  the  due  alteration,  combination,  or  proportioning 
of  which,  will  entirely  depend  the  ultimate  form :  that  is,  whether 
the  metal  be  allowed  to  continue  as  a  cylinder ;  to  expand  or  to 
contract,  either  as  a  cone  or  as  a  simple  curve  ;  or  to  serpentine  in 
in  any  arbitrary  manner,  according  as  the  one  or  other  action  is 
allowed  to  predominate  with  the  gradual  development.  The  treat- 
ment of  such  works  with  the  hammer,  is  unlike  spinning  the  teapot, 
at  those  parts  of  the  work  where  the  metal  is  folded  down  in  close 
contact  with  the  solid  revolving  mould  therein  employed ;  but  in 
completing  the  upper  part  on  the  small  block,  Fig.  243,  the  burn- 
isher and  the  rubber  may  be  considered  equivalent  to  the  two  anta- 
gonist forces,  which  lead  the  hammered  vessel  inwards,  or  outwards 
at  the  will  of  the  operator. 

This  subject  is  too  wide  to  enable  any  thing  more  to  be  offered 
than  a  few  general  features,  and  I  shall  therefore  proceed  to  trace 
briefly  the  practice  in  some  examples. 

Figs.  258  259. 


Fig.  258  represents  the  first  stage  of  making  the  half  of  a  cop- 
per ball;  the  metal  is  first  driven  with  a  mallet  into  a  concave  bed, 
generally  of  wood,  in  which  it  is  hastily  gathered  up  to  a  sweep 
of  about  the  third  part  of  a  sphere,  as  a,  a,  Fig.  259 ;  but  this  puck- 
ers up  the  edge  like  a  piece  of  fluted  silk,  or  the  serpentine  margin 
of  many  shells,  in  the  manner  represented  at///  Fig.  260,  which 
is  of  twice  the  size  of  259. 

The  next  step  is  to  remove  the  flutes  or  puckers  by  means  of 
blows  of  the  raising  hammer,  applied  externally  as  indicated  by 
the  black  lines  at  h,  Fig.  260;  and  in  Fig.  261  are  represented,  on  a 
still  more  enlarged  scale,  the  relative  positions  of  the  hammer, 


WORKS   IN   SHEET   METAL. 


307 


anvil,  and  work.  Thus  A  represents  the  globular  face  of  the 
anvil,  B  the  rounded  edge  of  the  raising  hammer,  which  like  the 
pane  of  an  ordinary  hammer,  stands  at  right  angles  to  the  handle, 
and  a  1,  shows  the  work,  a  being  the  edge,  and  1  the  point  of  the 
flute.  The  blows  of  the  hammer  are  made  to  fall  nearly  on  the 
centre  o,  of  the  anvil,  and  at  a  small  angle  with  the  perpendicular, 
the  hand  being  on  the  side  a.  A  few  blows  are  given  as  tangents, 
or  directly  across  the  point  of  the  flute,  and  when  it  exceeds  the 
width  of  the  hammer,  oblique  blows  are  given  to  restore  the  pointed 
character,  to  be  followed  by  other  blows  parallel  with  the  first,  as 
shown  at  h,  Fig.  260.  These  hollow  blows  cause  the  sides  of  the 
flutes  to  slide  into  one  another,  almost  as  when  two  packs  of  cards, 
placed  like  the  ridge  of  a  house,  penetrate  into  each  other  and  sink 
down  flat :  in  a  manner  somewhat  resembling  that  by  which  the 
original  and  extreme  margin  in  Fig.  257,  becomes,  by  the  succes- 
sive blows,  contracted  to  the  inner  circle ;  but  in  the  present  case 
the  plait  slides  down  to  the  general  curve  of  the  spherical  dish. 


Figs.  260 


261. 


If,  however,  the  puckers  of  a  large  globe  were  entirely  removed 
by  hollow  blows,  the  central  lines  of  the  flutes  would  become 
thickened,  and  therefore  solid  blows  are  mingled  with  them,  or 
rather  the  one  blow  partakes  of  the  two  natures.  Thus  from  the 
curvature  and  oblique  position  of  the  hammer,  Fig.  261,  its  face  is 
solid  at  s,  to  that  part  immediately  below  it,  but  towards  h,  it 
rather  bends  than  thins ;  the  flatter  the  curves  of  the  two  surfaces, 
the  greater  the  extent  of  the  solid  or  thinning  blows.  The  plaits 
are  not,  however,  entirely  gathered  up,  as  the  dish  a,  a,  Fig.  259, 
always  opens  a  little,  from  the  metal  becoming  stretched  under  the 
treatment  for  removing  the  flutes. 

Throwing  the  works  into  flutes  as  described  is  not  imperative, 
for  the  hemisphere  might  be  entirely  raised,  as  in  the  succeeding 
step,  by  blows  on  the  outer  surface  upon  a  convex  tool  or  head, 
but  the  flutes  quicken  the  process,  and  speedily  give  a  concavity 
which  is  convenient,  as  it  makes  the  work  hang  better  on  the 
rounded  face  of  the  anvil. 

The  outer  curve  a  a,  Fig.  259,  p.  306,  which  represents  the  cop- 
per dish  when  the  puckers  have  been  removed,  will  not  be  sent 
into  the  hemispherical  form,  or  the  inner  line  d  d,  at  one  process, 
but  will  progressively  assume  the  curvatures  b  I,  c  c,  and  some- 


308  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

times  many  others ;  neither  will  the  work  be  changed  from  the 
curve  a  a,  to  that  of  b  b,  at  one  sweep,  or  as  with  the  burnisher  in 
spinning  even  by  one  consecutive  ring  or  wave.  The  hammer 
must  necessarily  operate  by  successive  blows  arranged  in  circles, 
the  proximity  of  which  circles  will  at  length  include  within  their 
range  the  entire  sweep  a  a,  or  b  b,  each  of  which  is  called  a  course: 
and  before  proceeding  from  one  course  or  sweep  to  the  next,  the 
metal  requires  to  be  annealed. 

Figs.  261  and  262  explain  the  transition  or  conversion  from  the 
first  sweep  a,  to  the  second  sweep  b ;  the  black  lines  represent  the 
metal  after  a  circles  of  blows  have  been  given.  Fig.  262  shows 
the  narrow  edge  of  the  raising-hammer,  in  the  act  of  descending 
upon  the  centre  of  the  head  or  stake,  and  as  a  tangent  to  the  circle ; 
it  first  throws  in  a  little  rim  at  1,  which  connects  the  new  and  old 
sweeps  by  a  curve  or  ogee:  then  another  little  circle  2,  will  be  simi- 
Figs.  262  263. 


\.J..J 

a     b  n     p 

larly  gathered  in,  then  3,  4,  5,  and  so  on,  up  to  the  edge.  Now 
the  artifice  consists  in  making  the  intervals  both  of  the  great 
sweeps,  a,  b,  c,  Fig.  259,  and  of  the  little  waves  1,  2,  3,  of  Fig.  262, 
as  large  as  practicable,  provided  they  do  not  cause  the  exterior 
metal  to  pucker  or  become  in  plaits,  as  this  would  endanger  its 
ultimately  cracking  at  those  places,  where  the  metal  might  have 
become  plaited. 

In  thus  raising-in  the  metal,  it  necessarily  becomes  thickened 
from  its  contraction  in  diameter,  but  as  in  Fig.  261  the  hammer  at 
h,  gives  a  hollow  blow  and  bends,  whilst  the  part  s,  gives  a  solid 
blow  and  thins,  the  two  effects  are  thus  combined ;  and  when  they 
are  duly  proportioned,  by  a  hammer  more  or  less  round,  and  blows 
more  or  less  oblique,  the  true  thickness  as  well  as  the  desired 
change  of  figure  are  both  obtained. 

It  is  easier  to  get  the  hemisphere  by  a  little  excess  of  thinning, 
or  by  a  superfluity  of  blows :  so  that  the  less  skilful  workman  will 
use  a  piece  of  copper  of  seven  inches  diameter,  with  additional 
blows,  for  a  six  inch  hemisphere ;  but  the  more  skilful  will  take  a 
piece  of  seven  and  a  half  inches  diameter,  and  obtain  the  work 
with  less  labor.  Occasionally,  when  the  work  is  common  and 


WORKS   IN   SHEET   METAL.  309 

thin,  from  three  to  six  hemispheres  or  other  pieces  are  hollowed 
together,  the  outer  piece  is  cut  as  a  hexagon  or  octagon,  and  its 
angles  are  bent  over  to  embrace  the  inner  pieces,  before  the  pro- 
cess of  hollowing  is  begun,  and  which  scarcely  consumes  more 
time  than  for  one  only.  This  is  a  general  practice  in  hollowing  tin- 
works,  such  as  the  covers  of  sauce-pans,  as  the  number  of  thick- 
nesses divide  the  strength  of  the  blows ;  the  several  pieces  are  then 
twisted  round  at  intervals,  so  as  to  arrange  them  in  a  different 
order,  which  mixes  the  little  imperfections,  and  tends  to  their 
mutual  correction :  the  raising  process  represented  in  Fig.  262  is 
also  performed  upon  two  or  three  pieces  at  a  time,  when  they  are 
sufficiently  thin  to  permit  it. 

One  of  the  most  conspicuous  and  remarkable  examples  of  raised 
works  is  the  ball  and  cross  of  St.  Paul's  Cathedral,  London.  The 
old  ball  consisted  of  sixteen  pieces  riveted  together ;  the  present, 
also  6  feet  in  diameter  and  £  inch  thick,  was  raised  in  two  pieces 
only,  and  may  therefore  be  considered  to  mark  the  improvement 
in  the  coppersmith's  art  in  making  large  works,  such  as  sugar- 
pans,  stills,  etc. 

The  metal  was  first  thinned  and  partly  formed  under  the  tilt- 
hammer  at  the  copper-mills,  or  sunk  in  a  concave  bed ;  the  raising 
was  effected  precisely  as  explained  in  Fig.  262,  and  with  hammers 
but  a  little  larger  than  usual ;  the  two  parts  were  riveted  together 
in  their  place,  and  the  joint  is  concealed  by  the  ornamental  band. 

All  the  work  is  modern,  and  is  rrfbstly  hammered  up,  except  the 
cast  gun-metal  consoles  beneath  the  ball,  which  formed  part  of  the 
original  metallic  edifice ;  a  name  to  which  it  is  justly  entitled,  the 
height  being  29  feet,  and  the  weight  of  copper  3J  tons.  The  new 
ball  and  cross  are  strengthened  by  a  most  judicious  inner  framing 
of  copper  and  wrought-iron  bars,  stays,  bolts,  and  nuts,  extending 
through  the  arms  and  downwards  into  the  building;  thus  adding 
about  2  tons  of  iron  to  the  load  of  copper,  and  to  the  38  ounces  of 
gold  used  in  its  decoration. 

Having  conveyed  the  full  particulars  for  raising  a  hemispherical 
shape,  the  modifications  of  treatment  required  for  various  other 
forms  will  be  sufficiently  apparent.  Thus,  below  the  dotted  lines 
a  d,  in  Fig.  263  the  sweeps  are  exactly  the  same  as  in  Fig.  259, 
but  the  metal  rises  higher  .from  having  been  originally  larger ;  in 
the  courses  g  h,  it  is  first  kept  rather  thicker  on  the  edge,  and  to- 
wards the  conclusion,  it  is  thinned  on  the  edge  to  the  common 
substance,  and  curled  over  by  hollow  blows  from  within,  although 
the  whole  figure  might  be  produced  by  external  blows,  but  which 
would  be  a  more  tedious  method. 

On  the  other- hand,  by  the  continuance  of  the  rawing  in,  ex- 
.  plained  by  diagram  262,  the  metal  would  be  gathered  into  a  smaller 
diameter  through  the  »teps  i,  j,  k,  I,  in  the  latter  of  which  the  metal 
would  become  thickened,  unless  the  solid  or  thinning  blows  were 
allowed  to  predominate.  If  enough  metal  had  been  given  in  the 
first  instance,  when  the  mouth  had  been  contracted  as  to  the  form 


310  THE  PRACTICAL   METAL -WORKER'S  ASSISTANT. 

of  a  teapot,  it  might  be  extended  upwards  as  a  cylindrical  neck, 
in  the  manner  explained  in  Fig.  256,  and  curled  over  at  the  top, 
as  on  the  opposite  side  of  Fig.  263.  at  h, 

To  lessen  the  labor  of  raising  works  from  a  single  flat  plate, 
soldering  is  sometimes  resorted  to;  thus  the  teapots,  Figs.  190  and 
192,  page  284,  might  be  made  in  two  dished  pieces,  and  soldered 
at  the  largest  diameter ;  the  lofty  vase  or  coffeepot,  Fig.  194,  could 
be  made  from  a  cylinder  of  midway  diameter  soldered  up  the  side, 
the  bulge  being  set-out  by  thinning  the  metal,  and  the  contraction 
above  being  drawn-in  by  hollow  blows. 

Vases  in  the  shape  of  an  earthen  oil  jar,  or  of  the  line  I  d  n, 
Fig.  263,  could  be  made  from  a  cone  such  as  o  p,  with  a  bottom 
soldered  in ;  these  preparations  would  save  the  work  of  the  ham- 
mer, although  such  forms,  and  others  far  more  difficult,  could  be 
raised  entirely  by  the  hammer  from  a  flat  piece  of  metal. 

Should  any  of  the  above  vessels  require  a  solid  thickened  edge 
or  lip,  beyond  that  which  would  result  from  the  dra wing-in  of  the 
metal,  it  would  be  necessary  to  select  a  piece  of  metal  of  smaller 
diameter  but  thicker,  and  to  retain  the  margin  of  the  full  thick- 
ness by  directing  all  the  •  blows  within  the  same  ;  sometimes,  on 
the  other  hand,  works  require  to  be  thinned  on  the  edge ;  these 
are  then  cut  out  proportionally  smaller  than  their  intended  sizes, 
as  illustrated  by  the  following  example,  which  is  considered  the 
most  difficult  of  its  kind. 

The  bell  of  a  French  horn*together  with  the  first  coil  of  the 
tube,  are  made  of  a  flat  strip  of  metal  about  4  feet  long  and  2 
inches  wide ;  for  making  the  bell  of  the  instrument,  there  is  an 
enlargement  at  one  end  of  the  strip,  in  the  form  of  the  funnel 
piece  189,  and  of  the  width  of  16  to  22  inches,  the  smaller  piece 
being  adopted  when  the  bell  is  required  to  be  very  thin.  The 
narrower  piece  of  metal,  when  first  bent  up,  much  resembles  the 
butt  end  of  a  musket,  terminating  in  a  small  tube ;  the  metal  is 
united  and  soldered  down  the  edge  with  a  cramp  or  dovetail  joint, 
Fig.  232  ;  it  is  next  thrown  into  a  conical  form  of  about  five  inches 
diameter,  and  expanded  from  within,  first  with  blows  of  a  wooden 
mallet  upon  a  wooden  block,  and  then  with  those  of  a  hammer  on 
iron  stakes. 

When  nearly  finished,  or  about  one  foot  diameter,  it  is  ham- 
mered very  accurately  upon  a  cast-iron  mould  turned  exactly  to 
the  form  of  the  bell,  which  is  thus  rendered  much  thinner  than 
the  general  substance,  and  remarkably  exact ;  the  band  containing 
the  wire  for  stiffening  the  edge  of  the  bell  is  attached  by  dexterous 
hammering,  and  without  solder.  To  bend  the  tube  to  the  curve 
without  disturbing  its  circular  section,  it  is  filled  with  a  cement, 
principally  pitch,  which  allows  the  tube  to  be  bent  to  the  scroll  of 
the  instrument,  without  suffering  the  metal  to  be  puckered  or  dis- 
turbed from  its  true  circular  section ;  and  in  bending  similar  tubes 
to  smaller  curves,  they  are  filled  with  lead.  These  materials  serve 
as  flexible  and  fusible  supports,  which  are  easily  removed  when 
no  longer  required. 


WORKS   IN   SHEET  METAL. 


311 


Should  any  of  the  raised  works  have  ornamental  details,  suoh 
as  concave  or  convex  flutes,  or  other  mouldings,  they  would  be 
mostly  overlooked  until  the  general  forms  had  been  given ;  and 
then  every  little  part  would  be  proceeded  with  upon  the  same 
principles  of  solid  and  hollow  blows.  Each  of  the  series  of  flutes 
would  be  first  slightly  developed  all  around  the  object,  then  more 
fully,  and  so  on  until  the  completion  ;  when,  however,  the  details 
are  so  large,  as  to  form  what  may  be  considered  integral  parts,  it 
is  necessary  to  prepare  for  them  at  an  earlier  stage. 

Thus,  to  take  an  excellent  familiar  example,  let  JFig.  264  repre- 
sent plans,  265  sections,  and  266  elevations  of  jelly  moulds,  many 
of  which  require  the  greatest  skill  of  the  coppersmith.  The  gen- 
eral outline  is  that  of  a  cylinder  abed,  upon  a  larger  cylinder  ef 
g  h,  as  a  base.  The  twelve  large  and  deeply  indented  flutes  or 
finials,  rise  perpendicularly  to  a  great  height  from  the  plane  sur- 
faces a  c  and  e  b,  and  yet  the  whole  is  hammered  out  of  one  flat 
plate. 

Figs.  264  2o5  260. 


a                             c 

..        T-                                                                                   J        _ 

1 

1 

C 

The  first  step  is  to  raise  the  summits  of  the  flutes  i  or  k,  pre- 
paratory to  the  general  formation  of  the  upper  cylinder  abed, 
and  then  the  two  are  worked  up  together,  leaving  for  a  time  the 
expanded  base  e  f  g  h,  but  ultimately  the  whole  receive  a  general 
attention  in  common.  If  the  flutes  were  polygonal,  and  terminated 
in  ornaments  like  spires  or  finials,  as  at  k,  they  would  be  first 
treated  as  if  for  the  more  simple  or  generic  form  *,  and  the  details 
would  be  subsequently  produced. 

The  skill  called  for  in  such  works  is  greatly  enhanced  by  the 
attention  which  is  required  to  preserve  a  nearly  uniform  thickness 
in  the  metal,  notwithstanding  the  apparent  torture  to  which  it  is 
submitted ;  and  this  is  only  endured  in  consequence  of  a  frequent 
recurrence  to  the  process  of  annealing,  which  reinstates  the  mallea- 
ble property. 

In  cases  of  extensive  repetition,  or  where  large  numbers  of  any 
specific  shape  are  required,  expensive  dies  of  the  exact  forms  are 
employed ;  but  these  are  only  applicable  to  objects  in  small  relief, 
and  to  those  in  which  the  parts  are  not  quite  perpendicular.  Dies 
would  be  entirely  inapplicable  to  objects  such  as  the  jelly  moulds, 
Fig.  265,  although  a  common  notion  exists  that  they  are  rapidly 


312  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

made  by  that  method,  but  which  is  in  general  utterly  impossible 
when  such  objects  are  made  in  one  piece.  In  all  such  cases  the 
metal  has  to  undergo  the  same  bend  ings  and  stretchings  between 
the  dies  as  if  worked  by  the  hammer,  and  which  unless  gradually 
brought  about  are  sure  to  cut  and  rend  the  metal.  The  pro- 
duction of  many  such  forms  with  dies  is  therefore  altogether  im- 
practicable. 

Figs.  267  268. 


For  example,  the  pattern  or  moulding,  z,  Fig.  267,  is  only  in 
small  relief,  and  yet  the  flat  piece  of  metal  a  would  be  cut  in  two 
or  more  parts  if  suddenly  compressed  between  the  dies  A  B,  as 
the  edges  i  j  would  first  abruptly  bend  and  then  cut  the  metal, 
without  giving  it  the  requisite  time  to  draw  in,  or  to  ply  itself 
gradually  to  the  die,  beginning  at  the  centre  as  in  the  process  of 
hammering. 

In  Fig.  268  the  successive  thicknesses  obliterate  the  effect  of  the 
acute  edges  of  the  bottom  die  B  ;  the  face  and  back  of  every  thick- 
ness differ,  as  although  parallel  they  are  not  alike,  but  they  become 
gradually  less  defined,  so  that  in  Fig.  268  the  top  die  A  requires 
nothing  more  than  a  flowing  line  with  slight  undulations.  There- 
fore, when  two  or  three  dozen  plates  are  inserted  between  the  dies 
A  B,  the  transition  from  a  to  z  is  so  gradual  that  the  metal  can 
safely  proceed  from  a  to  b,  from  b  to  c,  and  so  on,  and  it  will  be 
progressively  drawn  in  and  raised  without  injury.  When  one  or 
two  pieces  alone  are  required,  they  are  blocked-down  to  fit  the  mould 
by  laying  above  them  a  thick  piece  of  lead,  which  latter  is  struck 
with  the  mallet  or  hammer.  By  the  yielding  resistance  the  lead 
opposes,  the  thin  metal  is  drawn  into  the  die  with  much  less  risk 
of  accident  than  if  it  were  subjected  to  the  blows  without  the  in- 
tervention of  the  lead. 

In  producing  many  pieces,  however,  one  piece,  a,  is  added  at  the 
top,  between  every  blow,  and  one  piece,  z,  is  also  removed  from  the 
bottom.  Occasionally,  two,  three  or  more  are  thus  added  and  re- 
moved at  one  time,  and  generally,  as  the  concluding  step,  every 
piece  is  struck  singly  between  the  dies,  such  as  Fig.  267,  which 
exactly  correspond.  In  general  the  process  of  annealing  must  be 
also  resorted  to  once  or  more  frequently  during  the  transition  from 
a  to  z.  For  the  best  works  the  bottom  die  is  mostly  of  hardened 
steel,  sometimes  of  cast-iron  or  hard  brass.  The  top  die  is  also 
of  hardened  steel  in  the  best  works,  but  in  very  numerous  cases 


WORKS   IN  SHEET   METAL.  313 

lead  is  used,  from  the  readiness  with  which  it  adapts  itself  to  the 
shape  required. 

Stamping  is  very  common  for  many  works  in  brass,  but  which 
would  be  inapplicable  if  the  pieces  had  perpendicular  and  lofty 
sides,  as  in  Fig.  265,  page  311.  Such  lines,  although  rounded  by 
the  successive  thicknesses  of  metal,  would  still  present  perpendicu- 
lar sides,  and  therefore  render  this  mode  of  treatment  with  dies 
impracticable,  without  reference  to  cost.  Thimbles  are  raised  at 
five  or  six  blows,  between  as  many  pairs  of  conical  dies  successively 
higher,  but  the  metal  requires  to  be  annealed  every  time. 

PECULIARITIES  IN  THE  TOOLS  AND  METHODS. — Before  con- 
cluding the  remarks  on  raised  works,  it  may  be  desirable  to  revert 
to  some  of  the  principal  and  distinguishing  features  of  the  tools 
employed  in  these  arts.  As  a  general  rule,  it  will  be  observed  that 
all  these  manifold  shapes  are  the  more  quickly  obtained  the  more 
nearly  the  various  tools  assimilate  to  the  works  to  be  wrought. 
For  instance,  the  several  dies  and  swage  tools  quickly  and  accu- 
rately produce  mouldings  of  the  specific  forms  of  the  several  pairs 
of  dies ;  but  it  is  utterly  impossible  to  extend  this  method  to  all 
cases,  and  the  progressive  changes  required,  from  the  flat  disk,  the 
cylinder  or  cone,  as  the  case  may  be,  to  the  finished  object ;  and 
therefore  certain  ordinary  forms  of  tools  can  alone  be  employed, 
and  they  are  continually  changed  as  the  work  proceeds. 

For  hollow  works  with  contracted  mouths,  the  inner  tools  are 
required  gradually  to  decrease  in  bulk  and  to  increase  in  length, 
in  order  to  enter  the  cavities ;  but  they  can  be  rarely  the  exact 
counterparts  of  the  transient  forms  of  the  works,  nor  is  it  always 
desirable  they  should  be  so.  The  tools  are  often  required  to  be 
bent  at  the  end,  to  extend  within  a  shoulder  or  gorge.  The  small 
stake  in  the  tool,  Fig.  203,  is  an  example  of  this  ;  the  dotted  line 
represents  the  work,  such  as  the  perforated  cover  of  a  cylinder,  or 
the  top  of  a  teakettle.  The  strong  wrought-iron  arm  or  horse, 
Fig.  203,  carries  the  small  steel  tools,  and  which  latter  may  be  also 
fixed  by  their  shanks  either  in  the  bench  or  vice,  according  to 
circumstances. 

There  are  many  curious  circumstances  respecting  the  modifica- 
tion of  the  materials  for,  as  well  as  the  forms  of,  the  hammers  and 
anvils,  if  the  use  of  these  terms  may  be  extended  to  the  various 
contrivances,  by  the  action  and  re-action  of  which  thin  metal  works 
are  produced ;  and  the  concluding  examples  are  advanced  to  bring 
some  of  these  peculiarities  of  method  into  notice. 

The  plated  metals  have  so  thin  a  coating  of  silver,  that  they  re- 
quire more  expert  hammering  than  similar  works  in  solid  silver, 
otherwise  the  removal  of  the  bruises  left  by  the  hammer,  by  scrap- 
ing and  polishing,  might  wear  through  the  silver  and  show  the 
copper  beneath.  The  bruises  are  therefore  driven  to  the  copper 
side,  by  hammering  upon  the  silver  or  the  face,  with  a  very  smooth 
planishing  hammer,  and  covering  the  anvil  or  bottom  tool  with 
cloth.  On  account  of  the  elasticity  thus  given,  the  blows  become 


31-4  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

so  far  hollow  that  all  the  little  bruises  descend  to  the  copper  side, 
or  that  which  is  exposed  to  the  cloth,  and  the  face  becomes  per- 
fectly smooth. 

When  the  inside  of  a  vessel  is  required  to  be  smooth,  it  is  the 
hammer  that  is  covered  with  cloth,  stretched  over  it  by  an  iron 
ring,  and  the  polished  stake  or  head  within  the  vessel  is  left  uncov- 
ered ;  and  in  those  cases  in  which  the  work  is  required  to  be  good 
on  both  sides,  the  faces  both  of  the  hammer  and  anvil  are  each 
muffled ;  this  gives  them  some  of  the  elasticity  of  wooden  'tools, 
but  with  superior  definition  of  figure. 

Plated  works  are  generally  furnished  with  an  additional  thick- 
ness of  silver  at  the  part  to  be  engraved  with  a  crest  or  cipher,  in 
order  that  the  lines  may  not  penetrate  to  the  copper;  should  it, 
however,  be  requisite  to  remove  the  engraved  lines  for  the  substi- 
tution of  others,  the  following  mode  is  resorted  to. 

The  object  is  laid  upon  the  anvil  over  a  piece  of  sheet  lead  and 
it  is  struck  with  a  bare  hammer  upon  the  engraved  lines  ;  these  latter 
are  therefore  hollow  as  regards  the  face  of  the  hammer ;  in  conse- 
quence of  which,  the  re-action  of  the  lead  causes  it  to  rise  in  ridges 
corresponding  with  the  engraved  lines,  and  to  drive  the  thin 
plated  metal  before  it.  The  device  is  thus  in  great  measure  oblit- 
erated from  the  silver  face  and  thrown  to  the  copper  side,  so  as  to 
leave  much  less  to  be  polished  out ;  this  ingenious  method  is  ap- 
propriately called  reversing. 

In  making  vases,  such  as  Figs.  192  and  194,  page  284,  the  metal 
is  first  driven  into  concave  wooden  blocks  with  a  wooden  mallet,  as 
in  Fig.  258,  in  order  to  gather  up  the  metal  into  the  fluted  concave 
260,  but  without  making  any  sensible  alteration  in  its  thickness. 
In  the  next  stage  of  the  work,  metal  tools  are  alone  employed, 
whether  the  object  be  made  by  raising-in  with  hollow  blows,  or  by 
setting-out  with  solid  blows,  as  adverted  to;  and  the  sizes  and 
curvatures  of  the  tools  require  to  be  accommodated  to  the  changes 
of  the  work. 

Supposing  the  vases  to  have  either  concave  or  convex  flutes, 
ornamental  details  are  now  sketched  with  the  compasses  upon  the 
plain  surface  of  the  vase ;  and  if  from  the  shape  of  the  works 
swage  tools  similar  to  Fig.  212,  cannot  be  employed  for  raising 
the  projecting  parts,  they  are  snarkd-up,  by  the  method  represented 
in  Fig:  269. 

Thus  at  v  are  the  jaws  of  the  tail  vice,  in  which  the  snarling- 
iron  s,  is  securely  fixed :  the  extremity  b,  which  is  turned  up,  must 
be  sufficiently  long  to  reach  any  part  of  the  interior  of  the  vessel, 
but  yet  small  enough  to  enter  its  mouth.  The  work  is  held  firmly 
in  the  two  hands,  with  the  part  to  be  raised  or  set  out  exactly  over 
the  end  b  ;  and  when  the  suarling-iron  is  struck  with  a  hammer  at 
h,  the  re-action  gives  a  blow  within  the  vessel,  which  throw  the 
metal  out  in  the  form  of  the  end  of  the  tool,  whether  angular, 
cylindrical,  or  globular :  except  in  small  works,  two  individuals 
are  required,  one  to  hold  and  the  other  to  strike. 


WORKS   IX   SHEET   METAL.  315 

Figure  270  shows  the  last  stage  of  the  work  prior  to  polishing ; 
thus  in  finishing  the  flutes  and  other  ornaments  after  they  are 
snarled-up,  the  object  is  filled  with  a  melted  composition  of  pitch 
and  brick-dust — sometimes  the  pitch  is  used  alone,  or  common 
resin  is  added — the  ornaments  are  now  corrected  with  punches  or 


Figs.  269  270  271. 


chasing  tools  of  the  counterpart  forms  of  the  several  parts ;  some 
portions  of  the  metal  are  thus  driven  inwards,  whilst  those  around 
rise  up  from  the  displacement  and  reaction  of  the  pitch.  To  avoid 
injuring  the  lower  surface  of  the  work  it  is  supported  upon  a  sand- 
bag b,  like  those  used  by  engravers,  and  the  perpendicular  lines  p, 
denote  the  usual  position  of  the  chasing  tool. 

Works  in  copper  and  brass  are  sometimes  filled  with  lead  at  the 
time  of  their  being  chased,  but  the  silversmiths  and  goldsmiths 
are  studious  to  avoid  the  use  of  this  metal,  as,  if  it  gets  into  the 
fire  along  with  their  works,  it  is  very  destructive  to  them. 

Pitch  and  mixtures  of  similar  kind,  are  constantly  used  in  the 
art  of  chasing  in  its  more  common  acceptation  ;  from  its  adhesive 
and  yielding  nature  it  is  a  most  appropriate  support,  as  it  leaves 
both  hands  at  liberty,  the  left  to  hold  the  punch,  the  right  for  the 
small  hammer  used  in  striking  it. 

The  pitch-block,  Fig.  271,  is  employed  to  afford  the  utmost 
choice  of  position  for  works  from  the  smallest  size  to  those  of  six 
or  eight  inches  long.  The  lower  part  is  exactly  hemispherical,  and 
it  is  placed  upon  a  stout  metal  ring  or  collar  of  corresponding 
shape,  covered  with  leather.  The  mass  of  metal  makes  a  firm 
solid  bed  to  sustain  the  blows,  and  the  ball  and  socket  contact, 
allows  the  work  to  assume  every  obliquity,  and  to  be  twisted 
round  to  place  any  part  towards  the  artist. 

Large  flat  works  in  high  relief  are  frequently  sketched  out  and 
commenced  from  the  reverse  face,  the  prominent  parts  of  the  sub- 
ject being  sunk  into  the  pitch,  which  after  a  short  time  must  be 
melted  away  to  allow  the  metal  to  be  annealed ;  and  this  is  fre- 
quently required  when  the  works  are  much  raised.  In  the  con- 
cluding steps  the  artist  works  from  the  face  side. 

Many  of  the  chased  works  are  cast  in  sand  moulds  from  metal 
models,  which  have  been  previously  chased  nearly  to  the  required 
forms;  the  castings  are  first  pickled  to  remove  the  sand  coat,  and  in 
such  cases,  chisels  and  gravers  are  somewhat  used  in  removing  the 
useless  and  undercut  parts. 


316  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

Many  ancient  specimens  of  armor,  gold  and  silver  plate,  vases 
and  ornaments,  are  excellent  examples  of  raised,  chased,  and  in- 
laid and  engraved  works,  both  as  regards  design  and  execution. 
In  our  own  times,  the  Hungarian  silversmith,  Szentepeteri,  has 
produced  a  very  remarkable  alto-relievo  in  copper,  taken  from  Le 
Brun's  picture  of  the  battle  of  Arbela,  in  which  some  of  the  legs 
of  the  horses  stand  out  and  are  entirely  in  relief  from  the  back- 
ground. 

The  art  of  chasing  may  be  considered  as  the  sequal  to  that  of 
forging  (that  is,  setting  aside  the  employment  of  the  red-heat),  but 
the  various  hammers  and  swage  tools  now  dwindle  into  the  most 
diminutive  sizes,  and  are  required  of  as  many  shapes  as  may  nearly 
correspond  with  every  minute  detail  of  the  most  complex  works. 
Some  of  them  are  grooved  and  checkered  at  the  ends,  and  others 
are  polished  as  carefully  as  the  planishing  hammers,  that  they  may 
impart  their  own  degree  of  perfection  and  finish  to  the  works ;  in  a 
similar  manner  that  the  polish  and  excellence  of  coins  and  medals 
are  entirely  due  to  that  of  the  dies  from  which  they  are  struck, 
the  chasing  process  being  as  it  were  a  minute  subdivision  of  the 
action  of  the  die  itself. 

THE  PRINCIPLES  AND  PRACTICE  OF  FLATTENING  THIN  PLATES 
OF  METALS  WITH  THE  HAMMER.— I  have  purposely  reserved  this 
subject  to  be  distinct,  on  account  of  its  great  general  importance  in 
the  arts,  and  have  placed  it  last,  in  order  that  the  various  applica- 
tions of  the  hammer  might  have  been  rendered  comparatively 
familiar ;  for,  although  the  plane  surface  may  appear  to  be  of  more 
easy  attainment  than  many  of  the  complex  forms  which  have  been 
adverted  to,  such  is  by  no  means  the  case. 

The  methods  employed  are  entirely  different  from  that  explained 
at  page  153,  in  reference  to  flattening  thick  rigid  plates,  which  are 
corrected  by  enlarging  the  concave  side,  with  blows  of  the  sharp  rect- 
angular edge  of  the  hack-hammer,  applied  within  the  concavity.  A 
method  which  bears  some  analogy  to  that  employed  by  the  joiner  in 
straightening  a  board  which  is  curved  in  its  width,  namely,  the 
contraction  of  its  convex  side  by  exposure  to  heat.  In  thin  metal 
plates  neither  of  these  modes  is  available,  as  the  near  proximity  of 
the  two  sides  causes  both  to  be  influenced  in  an  almost  equal 
degree  by  any  mode  of  treatment. 

Thin  plates  are  flattened  by  means  of  solid  and  hollow  blows, 
which  have  been  recently  explained,  but  they  require  to  be  given 
with  considerable  judgment ;  and  a  successful  result  is  only  to  be 
obtained  by  a  nice  discrimination  and  considerable  practice.  All 
therefore  that  can  be  here  attempted  is  an  examination  of  the  prin- 
ciple concerned,  and  of  the  general  practice  pursued ;  as  the  pro- 
cess being  confessedly  one  of  a  most  difficult  nature,  success  is 
only  to  be  expected  or  attained  by  a  strict  and  persevering  regard 
to  principle. 

As  respects  thin  works,  no  figure  is  so  easily  distorted  as  the 
true  plane,  and  this  arises  from  the  very  minute  difference  which 


WORKS   IX   SHEET   METAL.  317 

exists  between  the  span  or  chord  of  a  very  flat  arch,  and  its  length 
measured  around  the  curve.  For  example,  imagining  the  span  of 
an  arch  to  be  one  inch,  and  the  height  of  the  same  to  be  one-twen- 
tieth of  an  inch,  the  curve  would  be  only  about  one  200th  of  an 
inch  longer  than  the  span :  and  therefore,  if  any  spot  of  one  inch 
diameter  were  stretched  until,  if  unrestrained,  it  would  become  one 
inch  and  one  200th  in  diameter,  such  spot  would  raise  up  as  a 
bulge  one-twentieth  of  an  inch  high.  This  trivial  change  of  mag- 
nitude would  be  accomplished  with  very  few  blows  of  the  ham- 
mer, and  much  less  than  this  would  probably  distort  the  whole 
plate. 

In  general,  however,  there  would  be  not  one  error  only,  but 
several,  the  relationship  of  which  would  be  more  or  less  altered 
with  nearly  every  blow  of  the  hammer;  thence  arises  the  difficulty, 
as  the  plane  surface  cannot  exist  so  long  as  any  part  of  the  plate  is 
extended  beyond  its  just  and  proportional  size,  and  which  it  is  a 
very  critical  point  to  arrive  at. 

There  is  another  test  of  the  unequal  condition  of  flat  works  be- 
sides that  of  form,  namely,  their  equal  or  unequal  states  of  elasti- 
city, and  which  is  an  important  point  of  observation  to  the  work- 
man. For  instance,  if  we  suppose  a  plate  of  metal  to  be  exactly 
uniform  in  its  condition,  it  will  bend  with  equal  facility  at  every 
point,  so  that  bending  a  long  spring,  or  saw,  will  cause  it  to  assume 
a  true  and  easy  curve ;  but  supposing  one  part  to  be  weaker  than 
the  remainder,  the  saw  will  bend  more  at  the  weak  part,  and  the 
blade  will  become  as  it  were  two  curves  moving  on  a  hinge.  When 
such  objects  are  held  by  the  one  extremity  and  vibrated,  the  per- 
fect will  feel  as  a  uniformly  elastic  cane ;  the  imperfect,  as  a  cane 
having  a  slight  flawr  which  renders  it  weak  at  one  spot ;  and  in 
this  manner  we  partly  judge  of  the  truth  of  a  hand-saw,  as  in 
shaking  it  violently  by  the  handle,  it  will,  if  irregularly  elastic, 
lean  towards  the  character  of  the  injured  cane,  a  distinction  easily 
appreciated. 

Fig.  272^ 


A  thin  plate  of  metal  can  only  be  perfectly  elastic,  when  it  is 
either  a  true  plane  or  a  true  curve,  so  that  every  point  is  under  the 
same  circumstances  as  to  strength.  Thus  a  hemisphere,  as  at  a,  272, 
possesses  very  great  strength  and  rigidity  owing  to  its  convexity, 
but  as  the  figure  becomes  less  convex  it  decreases  gradually  in 
strength,  and  when  it  slides  down  to  the  plane  surface,  as  at  /,  the 
metal  assumes  its  weakest  form. 

A  nearly  plane  surface  will  necessarily  consist  of  a  multitude  of 
convexities  or  bulges  varying  in  size  and  strength,  connected  by 


318  THE    PRACTICAL    METAL-WORKER'S   ASSISTANT. 

intermediate  portions,  which  may  be  supposed  to  be  plane  surfaces ; 
the  whole  may  be  considered  as  greatly  exaggerated  in  the  figure. 
The  bulged  parts  are  stronger  than  the  plane  flat  parts,  it  follows 
that  the  bending  will  occur  in  preference  at  the  plane  or  weak 
parts  of  the  plate,  precisely  as  in  the  injured  cane. 

When  the  bulges  are  large  but  shallow,  they  flap  from  side  to 
side  with  a  noise  at  every  bending,  as  their  very  existence  shows 
that  they  cannot  rest  upon  the  neutral  or  straight  line ;  such  parts 
are  said  to  be  buckled,  their  ready  change  of  position  renders  them 
flaccid  and  yielding  under  the  pressure,  of  the  fingers,  and  they  are 
therefore  called  loose  parts,  but  at  the  same  time  it  is  certain  that 
they  are  too  large. 

On  the  contrary,  those  parts  which  are  intermediate  between  the 
bulges,  feel  tight  and  tense  under  the  fingers,  because  they  are 
stretched  in  their  positions  and  rendered  comparatively  straight, 
by  the  strong  edges  of  the  bulged  or  convex  parts :  the  flat  portions 
are  the  hinges  upon  which  the  bulged  parts  move,  and  such  flat 
parts  are  sensibly  too  small  for  their  respective  localities,  the  others 
being  too  large. 

Now,  therefore,  in  prescribing  the  rule  for  the  avoidance  of  these 
errors,  it  is  simply  to  treat  every  part  alike,  so  that  none  may  be 
stretched  beyond  its  proper  size  so  as  to  become  bulged,  and  thereby 
to  distort  the  whole  plate.  When  the  mischief  has  occurred,  the 
remedy  is  to  extend  all  the  too-small  parts,  or  the  hinges  of  the  bulges 
to  their  true  size,  so  as  to  put  every  part  of  the  plate  into  equal 
tension,  by  allowing  the  bulged  or  too-large  parts  room  to  expand. 
Uniform  blows  should  be  therefore  directed  upon  all  the  straight 
or  too-small  parts  of  the  plate,  the  force  and  number  of  the  blows 
being  determined  by  the  respective  magnitudes  of  the  errors,  and 
the  rigidity  of  the  plate. 

In  flattening  plates,  the  greater  part  of  the  work  is  done  with 
solid  blows  upon  a  true  and  nearly  flat  anvil ;  the  face  of  the  ham- 
mer is  slightly  round,  and  its  weight  and  the  force  of  the  blows  are 
determined  by  the  strength  of  the  plate,  the  slighter  plate  requiring 
more  delicate  blows,  and  being  more  difficult  to  manage.  In  the 
commencement,  the  rectangular  plate  is  hammered  all  over  with 
great  regularity  in  parallel  lines  beginning  from  one  edge ;  it  is 
generally  turned  over  and  similarly  treated  on  the  other  side.  Cir- 
cular plates  are  hammered  in  circular  lines  beginning  from  the 
centre,  that  is  supposing  the  plates  of  metal  to  be  soft,  and  in  about 
the  ordinary  condition  in  which  they  are  left  by  the  laminating 
rollers ;  as  the  equable  hammering  gives  a  general  rigidity,  which 
serves  as  a  foundation  for  the  correctional  treatment  finally  pur- 
sued. With  a  steel  plate  hardened  in  the  fire,  and  which  is  already 
far  more  rigid  than  the  soft  plate,  it  is  necessary  to  begin  at  once 
upon  the  reduction  of  the  errors  and  distortions,  which  usually 
occur  in  the  hardening  and  tempering. 

The  hammer  should  be  made  to  fall  on  one  spot  with  the  uni- 
formity of  a  tilt-hammer,  the  work  being  moved  about  beneath  it. 


WORKS  IN   SHEET   METAL. 


319 


As,  however,  the  regularity  of  a  machine  is  not  to  he  expected  from 
the  hand,  it  is  scarcely  to  be  looked  for  that  the  work  shall  be  at 
once  flat.  Whilst  the  errors  are  tolerably  conspicuous  or  consider- 
able, the  man  accustomed  to  the  work  will  still  keep  the  hammer 
in  constant  motion,  and  will  so  shift  the  work,  as  to  bring  the  tight 
parts  alone  beneath  its  blows,  hammering  with  little  apparent  con- 
cern just  around  the  margins  of  the  loose  parts,  or  at  the  foot  of 
eve*ry  rise.  As  the  plate  becomes  more  nearly  flat,  it  is  necessary 
to  proceed  more  cautiously,  and  to  hold  the  plate  occasionally  be- 
tween the  eye  and  the  light  to  learn  the  exact  parts  to  be  enlarged  ; 
the  straight-edge  is  also  then  resorted  to. 

In  many  works,  especially  in  saws  which  require  very  great 
truth,  the  elasticity  is  also  examined ;  this  is  frequently  done  by 
holding  the  opposite  edges  of  the  plate  between  the  fingers  and 
thumbs,  and  bending  them  at  various  parts.  As  previously  ex- 
plained, all  the  portions  which  are  technically  called  tight,  or  those 
lines  upon  which  the  loose  enlarged  parts  appear  to  move  as  on 
hinges,  are  strictly  the  parts  to  be  extended  by  gentle  hammering. 
For  instance,  supposing  that  in  the  plate,  Fig.  273,  there  were  only 


Figs.  273 


274. 


one  central  buckle  a,  the  whole  exterior  portion  would  require  to 
be  stretched,  beginning  from  the  base  of  the  bulge :  but  it  must  be 
remembered  the  extreme  edges  of  the  plate  will  peld  with  greater 
facility  than  the  more  central  parts,  and  therefore  require  some- 
what fewer  blows,  as  the  blows  are  all  given  as  nearly  as  possible 
of  the  same  intensity,  and  the  number  of  them  is  the  source  of 
variation. 

If,  as  it  is  more  to  be  expected,  there  are  two  or  more  loose  parts, 
sueh  as  a,  and  b  c,  the  more  quiescent  part  between  them  must  be  first 
hammered,  as  working  upon  any  loose'or  bulged  part  only  magnifies 
the  evil.  Where  the  intermediate  space  is  narrow,  as  at  d,  less  blows 
will  be  needed,  and  such  tight  parts  will  soon,  and  sometimes  very 
suddenly,  become  loose  from  the  two  bulges  melting  into  one.  It 
should  be  rather  the  general  aim  to  throw  the  several  small  errors 
into  a  large  one,  by  getting  the  plate  into  one  regular  sweep;  dealing 
the  blows  principally  between  the  dotted  lines,  not  carelessly  so  as 
to  increase  the  general  departure  from  the  plane  surface,  but  with 
an  acute  discrimination  to  lead  all  the  defects  in  the  same  direction, 
by  making  the  plate  as  it  were  a  part  of  a  very  great  cylinder,  as 
at  e  or/,  Fig.  274,  but  with  as  little  curvature  as  possible. 


320  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

When  this  is  accomplished,  and  that  the  work  is  free  from  loose 
parts,  it  is  hammered  on  the  rounding  side,  in  lines  parallel  with 
the  axis  of  the  imaginary  cylinder ;  so  that  in  e  the  lines  would  be 
parallel  with  the  edge  from  which  the  rise  commences,  and  in/,  or 
the  plate  which  is  bent  diagonally,  the  lines  of  blows  would  be 
necessarily  oblique,  although  as  regards  the  curvature,  the  same  as 
in  e.  The  reason  why  any  reduction  of  curvature  should  at  all 
result  from  this  treatment  (action  and  reaction  being  alike)  is  due 
to  the  greater  roundness  of  the  hammer  than  the  anvil ;  the  rounder 
hammer  effects  the  change  more  rapidly,  but  also  the  more  indents 
the  work. 

In  a  circular  saw,  the  general  aim  is  first  to  throw  the  minor 
errors  into  one  regular  concavity,  which  may  be  supposed  to  extend 
to  b  b  in  the  imaginary  section,  Fig.  275,  and  then  the  margin  a  b 
would  be  hammered  in  a  proportional  degree,  to  enlarge  it  until  it 
just  allowed  the  interior  sufficient  room  to  expand  to  the  plane 
surface. 


It  may  happen  in  the  course  of  the  hammering  that  from  b  to  b 
becomes  loose,  whilst  the  extreme  edge  a  a  is  also  loose,  and  that 
the  intermediate  part  towards  b  requires  to  be  stretched.  These 
minor  differences  cannot  be  told  alone*  by  bending  the  plate  with 
the  fingers,  as  errors  frequently  exist  which  are  too  minute  to  yield 
to  their  pressure,  and  then  the  eye  and  straight-edge  are  conjointly 
employed  in  the  examination. 

In  a  saw,  the  general  aim  is  to  leave  the  edge  rather  tight  or 
small,  as  then  the  small  amount  of  expansion  it  acquires  when  at 
work,  from  heat  and  friction,  will  enlarge  the  edge  just  sufficiently 
to  bring  the  saw  into  a  state  of  uniform  tension.  Otherwise,  if 
before  the  saw  is  set  to  work  the  edge  is  fully  large  enough,  when 
expanded  by  the  heat  it  is  almost  sure  to  become  loose  on  the 
edge,  and  to  vibrate  from  side  to  side,  without  proper  stability,  so 
as  to  produce  a  wide  irregular  cut,  and  make  a  flanking  whip-like 
noise,  arising  from  the  violent  vibration  of  the  buckled  parts 
of  the  plate  in  passing  through  the  saw  kerf;  the  sides  of  the 
wood  will  then  exhibit  ridges  like  the  ripple-marks  on  the  sandy 
shore. 

In  hammering  all  plates,  preference  should  in  the  like  manner 
be  given  to  keeping  the  edge  rather  small  or  stiff,  to  serve  as  a 
margin  or  frame  to  the  more  loose  parts  within.  It  giyes  a  degree 
of  stability  somewhat  as  if  the  object  had  a  thickened  rim,  and 
when  a  rim  really  exists,  the  process  of  flattening  is  comparatively 
easy. 

If  by  undue  stretching  the  edge  is  made  too  loose,  the  whole 
piece  becomes  flaccid  and  very  mobile,  and  we  seem  to  lose  the 


WORKS   IN   SHEET   METAL.  32 1 

governing  power,  or  those  retaining  points  by  which  the  changes 
of  the  plate  are  both  influenced  and  rendered  apparent.  The  edge 
should  be  therefore  always  kept  somewhat  tight,  from  being  pro- 
portionally less  hammered,  especially  as  the  edge  more  easily 
admits  of  expansion  than  the  inner  part. 

As  a  general  rule,  it  may  be  said,  that  every  part  of  the  plate 
which  is  straight  and  tense,  whilst  others  are  curved  and  flaccid, 
denotes  that  every  straight  part  is  under  restraint ;  and  that  its 
straightness  is  due  to  its  being,  as  it  were,  stretched,  either  length- 
ways or  around  its  edges,  by  the  other  parts,  which  are  too  loose, 
and  therefore  arched  and  also  strong.  In  such  cases,  the  straight 
lines  require  to  be  extended  in  length,  to  allow  sufficient  room  for 
the  curves  to  expand  to  their  proportional  sizes.  This  refers  not 
only  to  small  local  errors  towards  the  inner  part  of  the  plate,  as 
explained  by  diagram,  Fig.  273,  p.  319  ;  but  should  the  one  edge 
of  a  plate  be  tolerably  straight,  whilst  the  opposite  is  loose  and 
flaccid,  the  rule  also  applies  with  equal  truth,  and  the  straighter 
side  must  be  hammered.  In  this  case  the  curved  side  is  as  it  were 
a  great  bulge  cut  in  two  parts. 

Should  a  circular  saw  have  a  sudden  dent,  such  as  at  g,  Fig.  275, 
on  the  last  page,  standing  the  reverse  way,  and  which  may  result 
from  its  having  rested  upon  a  small  lump  of  coke  whilst  in  the 
fire,  the  first  blows  will  be  given  on  the  hollow  side,  between  the 
lines  i  i,  to  lessen  the  abruptness  of  the  margin  by  stretching  it  to 
the  dotted  curve,  and  then  it  will  be  driven  downwards  by  violent 
blows,  to  form  a  part  of  the  general  sweep  or  concavity.  A  little 
time  is  gained  by  these  driving  blows  over  the  mode  of  stretching 
by  the  hammer. 

The  foregoing  descriptions  have  all  referred  to  solid  blows,  upon 
the  face  of  the  hard  anvil,  but  to  expedite  the  process  recurrence 
is  often  had  to  blocking,  which  is  only  one  application  amongst 
many  others  of  a  wooden  anvil  or  block  with  a  narrow  flat-faced 
hammer,  such  as  Fig.  248.  In  this  case  the  blows  are  to  a  certain 
extent  hollow,  as  the  wood  immediately  beneath  the  hammer-face 
yields  to  the  blow,  whereas  the  margin  around  the  same  does  not. 
Such  blows  are  therefore  unquestionably  hollow,  and  lend  with 
very  little  stretching. 

The  blocking  is  considerably  employed  in  saw-making  after  the 
loose  parts  have  been  entirely  removed,  as  the  hollow  blows  cor- 
rect any  slight  errors  of  figure,  by  bending  alone,  and  with  little 
risk  of  stretching  the  plates,  if  the  work  be  delicately  performed. 

Towards  the  conclusion,  however,  all  the  different  modes  of  work 
are  required  to  be  used  in  combination,  as  the  true  condition  of 
the  plate  is  only-  the  exact  balancing  of  all  the  forces,  or  of  the 
tension  of  the  several  parts ;  and  it  constantly  happens  that  atten- 
tion to  one  error  causes  a  partial  change  and  fluctuation  throughout 
the  whole.  It  therefore  requires  great  tact  to  know  when  to  leave 
the  anvil  for  the  block,  and  when  to  return  to  the  anvil,  and  so  on 
alternately ;  and  also  which  side  of  the  plate  should  be  upwards 
21 


322  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

for  the  time,  which  particular  points  should  be  struck,  and  the 
'required  force  of  the  blows. 

Of  course,  within  certain  limits,  a  thick  plate  is  easier  to  hammer 
than  a  thin  one,  as  the  latter  is  difficult  from  its  excessive  mobility  ; 
also  a  soft  plate  of  iron  is  more  difficult  than  a  hard  plate  of  steel, 
although  the  latter  requires  more  blows  to  produce  the  same  effect ; 
but  when  the  works  are  very  thick  they  become  laborious,  and  the 
difficulty  always  increases  rapidly  with  the  size  of  the  plate. 

Those  who  n|ay  desire  to  practise  this  art  should  therefore  com- 
mence with  a  plate  some  4,  6,  or  8  inches  square,  and  moderately 
stout,  and  subsequently  proceed  to  pieces  larger  and  thinner.  They 
will  also  find  some  advantage  in  raising  the  anvil  to  within  about 
a  foot  of  the  eye,  as  the  alterations  can  be  then  more  easily  seen 
whilst  the  work  lies  on  the  anvil,  and  the  effect  of  any  predeter- 
mined blows  can  be  the  better  watched.  One  other  observance  is 
essential,  namely,  patience  ;  as,  although,  the  process  is  thoroughly 
reducible  to  system,  and  no  blow  should  be  struck  in  vain,  the 
beginner  will  frequently  find  it  necessary  to  pause,  examine,  and 
consider,  especially  as  the  errors  decrease ;  whereas  the  accus- 
tomed eye  will  follow  the  fluctuations  of  the  plate  almost  without 
intermission  of  the  blows,  and  will  also  accomplish  the  task  with 
the  fewest  possible  number  of  blows,  which  is  the  great  object. 

Indeed  it  may  happen  from  hammering  some  parts  of  a  plate 
excessively  and  improperly,  that  it  is  rendered  so  hard  and  rigid, 
as  to  make  its  correction  very  tedious,  or  indeed  nearly  impossible 
without  previous  annealing,  as  the  plate  might  burst  or  crack  from 
the  extension  being  carried  beyond  the  safe  limit  of  malleability. 
As  in  raised  works,  the  annealing  is  mostly  done  by  a  gentle  red 
heat;  but  in  hardened  steel  plates,  a  slight  increase  of  temperature 
barely  sufficient  to  discolor  the  plate,  will  make  a  perceptible  dif- 
ference ;  and  this  latter  process  is  always  the  last  step  in  making 
a  saw,  in  order  to  restore,  by  a  gentle  heat,  the  proper  elasticity 
which  has  been  mysteriously  lost  in  the  grinding,  polishing,  and 
hammering  required  in  its  manufacture. 


CHPTER  XVIII. 

PROCESSES   DEPENDENT  ON   DUCTILITY. 

DRAWING  WIRES,  ETC. — The  ductility  of  many  of  the  metals 
and  alloys,  or  the  quality  which  allows  them  to  be  drawn  into 
wires,  is  applied  to  a  variety  of  curious  uses  in  the  manufacturing 
arts,  and  the  process  may  be  viewed  as  the  sequel  to  the  use  of 
grooved  and  figured  rollers ;  but  the  ductile  metals  submit  to  this 
process  with  various  degrees  of  perfection. 


PROCESSES   DEPENDENT   ON   DUCTILITY.  323 

In  drawing  wire,  the  metal  is  first  prepared  to  the  cylindrical 
form,  either  directly  by  casting,  or  between  rollers  with  semicir- 
cular grooves ;  and  the  process  is  completed  by  pulling  the  metal 
through  a  series  of  holes  gradually  less  and  less,  made  in  a  me- 
tallic plate,  by  which  the  wire  becomes  gradaally  reduced  in  size, 
and  elongated ;  but,  as  in  rolling,  the  process  of  annealing  must 
be  resorted  to  at  proper  intervals. 

In.  general,  the  draw-plates  are  made  of  hardened  steel,  and 
they  are  formed  upon  the  same  principle,  whether  for  round, 
square,  or  complex  sections,  either  solid  as  wires,  or  hollow  as 
tubes ;  the  substance  of  the  metal  is  partly  kept  back,  as  in  a 
wave,  by  a  narrow  ridge  within  the  draw-plate,  acting  as  a  bur- 
nisher. 

The  plates  are  generally  made  of  hardened  steel,  or  else  of  alloys 
of  partly  similar  nature,  which  allow  the  holes  to  be  contracted 
and  repaired,  by  closing  them  with  blows  of  a  pointed  hammer  or 
punch  around  the  hole. 

The  holes  for  round  wires  are  sometimes  ground  out  from  both 
sides  upon  the  same  brass  cone  or  grinder,  the  sides  of  which  vary 
in  obliquity  from  10  to  30  degrees,  according  to  the  metal  to  be 
drawn  ;  for  the  sake  of  strength  the  ridge  is  mostly  nearer  to  the 
side  on  which  the  metal  enters,  and  the  sharp  edge  is  also  removed, 
either  by  wriggling  the  plate  upon  the  grinder  in  order  to  round 
the  inside,  or  in  any  other  manner. 

The  end  of  the  wire  is  pointed,  to  enable  it  to  be  passed  through 
the  hole,  and  it  is  then  caught  by  a  pair  of  nippers,  themselves  at 
the  extremity  either  of  a  chain,  rope,  toothed  rack,  or  screw,  by 
which  the  wire  is  drawn  through  by  rectilinear  motion.  The  nip- 
pers or  dogs  resemble  very  strong  carpenters'  pincers  or  pliers,  the 
handles  of  which  diverge  at  an  angle ;  they  are  sometimes  closed 
by  a  sliding  ring  at  the  end  of  the  strap  or  chain,  which  slides 
down  the  handles  of  the  nippers  ;  there  are  some  other  modifica- 
tions, all  acting  upon  the  same  principle,  of  compressing  the  nip- 
pers the  more  forcibly  upon  the  wire  the  greater  the  draught.  It 
requires  a  proportionally  strong  support  to  resist  the  strain ;  and 
to  avoid  the  fracture  of  the  hardened  steel  clraw-plate,  it  is  usually 
placed  against  a  strong  perforated  plate  of  wrought-iron,  In 
manufactories  where  large  quantities  of  wire  are  made,  the  wire  is 
more  usually  attached  to  the  circumference  of  a  reel,  which  is 
made  to  revolve  by  steam  or  other  power. 

It  is  necessary  often  to  anneal  the  wire,  but  no  general  rule  can 
be  stated  in  respect  to  its  recurrence ;  and  before  resuming  the 
drawing  process,  the  wire  is  invariably  immersed  in  some  acid 
liquor  or  pickle,  to  remove  the  slight  coating  of  oxide,  which 
would  otherwise  rapidly  destroy  the  plates  (as  many  of  these  me- 
tallic oxides  are  used  in  polishing),  in  general  some  lubricating 
matter  is  applied  to  reduce  the  friction,  as  beer-grounds,  starch- 
water  or  oil ;  and  for  gold  and  silver,  wax  is  generally  use- 1. 

Most  of  the  wire  is  drawn  upon  reels,  and  is  therefore  met  with 


824  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

in  circular  coils,  and  it  is  necessary,  in  almost  every  case,  to 
straighten  it  before  use.  The  soft  annealed  wires,  such  as  the  cop- 
per wire  used  for  bell-hanging,  the  soft  iron  binding-wire  used  in 
soldering,  and  others,  are  stretched  and  straightened  by  fixing  the 
one  end,  and  pulling  the  other  with  a  pair  of  pliers ;  or  short  pieces 
of  soft  wire  may  be  straightened  by  rolling  them  between  two  flat 
boards. 

So  steel  wire  for  making  needles  is  straightened  by  rolling  or 
rubbing:  it  is  cut  up  in  lengths  of  4  or  5  inches,  and  arranged  in 
cylindrical  bundles,  within  iron  hoops  of  4  inches  diameter ;  the 
rubber  is  a  bar  of  cast-iron,  about  two  feet  long,  narrow  enough  to 
lie  between  the  rings. 

The  hard-drawn  and  unannealed  wires,  used  for  making  pins, 
bird-cages,  blinds,  and  numerous  other  wire-works,  are  too  elastic 
to  yield  to  the  above  methods,  and  Fig.  276  represents  the  mode 
employed  to  take  the  spring  out  of  them,  or  in  other  words,  to 
straighten  these  hard  wires.  The  coil  of  wire  on  the  reel^  which 
revolves  on  a  pin,  is  drawn  through  the  riddle,  g,  by  the  pliers. 
The  riddle  is  a  piece  of  wood  or  metal  with  sloping  pins,  which 
lean  alternately  opposite  ways,  so  as  to  keep  the  wire  close  down 
on  the  board,  and  yet  to  compel  it  to  pursue  a  slightly  zigzag,  or 
rather  serpentine  course,  which  is  considerably  magnified  in  the 
figure. 

In  practice,  the  riddle  is  made  wider  than  represented,  so  as  to 
contain  about  half  a  dozen  rows  of  pins  suitable  to  as  many  sizes 
of  wire ;  between  every  set  of  pins,  and  fixed  close  down  to  the 
board,  is  a  straight  wire  about  three  times  the  diameter  of  one 
to  be  straightened:  very  great  importance  is  attached  to  this  latter 
or  central  wire ;  being  itself  straight,  it  serves  as  a  metallic  bed  for 
the  small  wire  to  run  upon,  and  it  thereby  gets  worn  into  furrows 
crossing  it  obliquely  from  pin  to  pin.  The  board  is  retained  by 
two  staples  at  the  Jar  end,  which  fit  loosely  on  two  studs  or  nails 
driven  into  the  work-bench. 


Figs.  276  277. 


The  pins  are  equivalent  to  the  three  forces  a,  b,  c,  of  the  bend- 
ing-machine,  page  289,  several  times  referred  to.  Were  the  first 
three  pins  critically  placed,  they  would  suffice  to  bend  the  wire  to  the 
limit  of  its  permanently  elastic  force,  and  would  leave  it  perfectly 


PROCESSES   DEPENDENT  ON  DUCTILITY.  325 

straight ;  commonly,  however,  five  pins  are  .used,  and  sometimes 
seven-  or  nine.  The  same  riddle  will  not  serve  for  wires  differing 
in  diameter ;  and  were  this  simple  tool  more  expensive,  so  as  to 
render  it  desirable,  a  universal  riddle  might  be  made  by  placing 
the  pins  b  and  d,  under  a  simple  screw-adjustment;  but  in  prac- 
tice, a  tap  of  the  hammer  is  found  sufficient  to  correct  their  posi- 
tions. $-. 

It  is  necessary  to  be  very  particular  in  pulling  the  wire  through, 
not  to  allow  it  to  lean  sensibly  against  either  of  the  last  two  pins, 
or  it  will  assume  a  curve ;  and  in  this  manner,  by  drawing  the  wire 
designedly  at  different  angles,  it  may  be  thrown  into  any  required 
circular  arc,  instead  of  the  right  line. 

Cylindrical  shafts  may  be  viewed  as  large  wires,  and  when  they 
are  turned  with  ordinary  care,  in  a  slide-lathe  with  a  back-stay,  it 
becomes  pretty  certain  that  the  shafts  are  circular,  and  of  true  diam- 
eters ;  but  they  are  frequently  more  or  less  crooked  or  bent  when 
they  leave  the  lathe. 

la  straightening  the  axes  or  shafts  intended  for  the  Calculating 
Machine,  which  were  of  steel,  about  6  to  10  feet  long  and  £  to  1 
inch  diameter,  three  half-round  dies,  Fig.  277,  a,  c,  fixed  to  the  bed 
of  a  fly-press,  and  b,  to  the  screw  of  the  same,  which  was  so  adjusted 
that  b  could  only  bend  the  portion  of  the  shaft  between  a,  c,  to  the 
limit  of  its  elasticity ;  and  therefore,  by  keeping  the  press  con- 
stantly at  work,  drawing  the  rod  through,  and  twisting  it  round  so 
as  to  bend  it  at  every  point  of  its  length,  every  shaft  was  made  per- 
fectly straight. 

The  straightening  of  black  wrought-iron  shafts  previous  to  turn- 
ing, is  now  accomplished  by  three  equidistant  rollers,  say  a  foot 
diameter  and  twelve  feet  long,  similar  to  Fig.  216,  p.  289.  The 
shaft  is  heated  to  redness,  and  the  centre  roller  is  raised  at  the  mo- 
ment of  its  introduction,  and  then  a  few  turns  are  given  to  the 
whole ;  this  straightens  the  shaft,  and  retains  it  so  until  partially 
cooled ;  the  other  end  of  the  shaft,  should  it  exceed  the  length  of 
the  rollers,  is  then  heated,  and  treated  in  the  same  manner. 

All  these  modes  are  highly  useful,  as  they  operate  upon  the  ma- 
terials without  partially  condensing  any  point,  from  which  unequal 
treatment  a  loss  of  figure  would  be  almost  certain  to  occur,  when 
any  such  condensed  point  is  partially  removed  by  the  turning-tool 
or  otherwise ;  as  it  appears  to  be  quite  impossible  to  prevent  all 
sorts  of  perplexities,  when,  by  any  mode  of  operation,  the  one  point 
of  a  material  receives  a  different  treatment  from  the  remainder. 

The  great  bulk  of  wire  is  cylindrical,  but  draw-plates  are  also 
made  of  various  other  forms,  as  oval,  half  round,  square,  and  trian- 
gular, for  the  wires  Figs.  278 ;  and  also  of  more  complex  forms,  as 
for  the  production  of  steel  of  the  sections  of  Figs.  279,  known  as 
pinion  wire,  the  whole  of  the  illustration  being  printed  from  the 
wires  themselves.  The  largest  of  279,  serves  for  the  pinions  of 
clocks,  and  the  smallest  for  those  of  watches;  in  these  cases  the 
entire  arbor  (which  carries  one  of  the  toothed  wheels)  is  made  of 


326 


THE   PRACTICAL   METAL-WOEKEE7S  ASSISTANT. 


pinion  wire,  but  the  -teeth  are  removed  from  every  part,  excepting 
that  which  works  into  the  adjoining  wheel  of  the  train.  The  plates 
for  pinion  wire  are  exactly  the  same  as  the  others  in  principle,  and 
exhibit  a  remarkable  degree  of  perfection  in  their  construction,  as 
for  every  size  there  must  be  a  series  of  many  holes  gradually 
assuming  the  form  of  a  circular  foliated  Gothic  window,  with  six, 
seven,  eight  or  more  foils.  • 


Figs.  278        279 


281. 


Fig.  282. 


f 


Some  of  the  printed  calicoes  and  muslins  are  also  curious  ex- 
amples of  the  wire-drawing  process;  the  pattern  Fig.  280,  consists 
of  no  less  than  205  different  pieces  of  copper  wire  of  various  forms, 
fixed  into  a  wood  block ;  the  surface  of  the  wires,  when  filed  smooth, 
are  printed  from  after  the  manner  of  printers'  types ;  the  few  de- 
tached pieces,  Fig.  281,  show  some  of  the  sections  of  such  wires, 
and  which  may  be  combined  in  endless  variety.  In  the  same 
manner  the  specimen  of  music,  Fig.  282,  is  printed  from  the  sur- 
faces of  detached  wires  and  slips  of  copper  fixed  in  a  wooden 
block ;  this  is  only  one  amongst  the  many  ingenious  processes  for 
printing  music  by  letter-press  or  surface  printing. 


Figs.  283 


284 


285 


2S6. 


Fig.  283  represents  the  double-plates  or  swage-bits  used  for  some 
of  the  pieces  in  Figs.  280  and  282;  the  dies  are  fitted  into  a  small 
frame  or  cramp  with  a  side  screw  (much  the  same  as  dies  for  cut- 
ting screws),  so  that  the  metal  may  be  gradually  reduced  by  one 


PROCESSES   DEPENDENT   ON   DUCTILITY.  327 

pair  of  swage-bits.  This  method  is  very  much  employed  by  the 
silversmith  and  goldsmith  for  mouldings,  the  tools  being  much 
cheaper  than  rollers :  the  piece  284  was  thus  prepared  for  the  edg- 
ing of  silver  and  gold  boxes;  it  is  bent  "round  to  the  form  of  the 
box  or  cover,  whether  square,  circular  or  oval,  and  the  rebate  on 
the  straight  side  of  the  band  serves  for  receiving  the  flat  plate  to 
constitute  the  cover. 

The  most  perfect  example  of  this  application  of  the  drawing 
process  is  in  the  British  Mint:  two  fixed  rollers  are  employed  after 
the  manner  of  a  draw-plate,  and  the  long  strip  of  gold  or  silver, 
when  rolled  very  nearly  to  the  thickness,  is  drawn  through  the 
stationary  rollers,  by  dogs  attached  to  one  of  the  links  of  an  endless 
chain,  which  is  in  continual  motion  from  the  steam-engine.  It 
was  found  barely  possible  to  make  the  surfaces  of  revolving  rollers 
so  truly  concentric  that  the  equality  of  thickness  in  the  metal 
could  be  obtained  with  the  rigorous  exactness  required,  so  as  to 
dispense  entirely  with  the  necessity  of  scraping  every  piece  individ- 
ually, a  mode  still  practised  in  some  of  the  Continental  mints. 

The  metal,  when  drawn,  is  tested  by  punching  out  one  blank  at 
each  end ;  these  are  carefully  weighed,  and  if  found  correct,  the 
whole  strip  is  punched  into  blanks ;  and  such  is  the  accuracy  of  the 
drawing  and  punching  processes,  that  without  the  smallest  after- 
adjustment,  any  fifty  or  one  hundred  blanks  weigh  alike  to  the 
fraction  of  a  grain. 

The  window  lead,  shown  in  section  in  Fig.  285,  does  not  admit 
of  being  drawn  in  the  ordinary  manner,  from  the  softness  of  the 
material,  nor  of  being  rolled,  because  of  its  undercut  section ;  the 
two  principles  are,  therefore,  curiously  combined  in  the  glazier's 
vice.  It  may  be  conceived  that  the  shade  lines  of  286,  represent 
parts  of  two  narrow  rollers  with  roughened  edges  (equal  in  thick- 
ness to  the  glass),  which  indent  the  bottom  of  the  groove,  and 
thereby  carry  the  lead  between  the  figured  side-pieces,  one 
only  shown.  In  some  cases  cutting  is  combined  with  drawing, 
cutters  are  then  fixed  to  the  draw  plate ;  this  method  has  been 
adapted  to  making  rules  and  similar  rods ;  and  in  perfecting  the 
flattened  wire  for  the  reeds  used  in  looms,  the  edges  are  rounded  by 
reeling  the  wire  beneath  a  forked  cutter,  a  process  intermediate 
between  turning  and  planing. 

The  process  of  wire-drawing  is  seldom  practised  by  the  general 
mechanician,  and  still  less  by  the  amateur ;  but  when  it  is  neces- 
sary to  produce  a  wire  either  of  some  unusual  section  not  prepared 
by  the  manufacturer,  or  that  the  equality  of  size  requires  more 
than  usual  exactness,  the  process  may  be  accomplished  in  the  small 
way,  by  fixing  the  draw-plate  in  the  tail- vice  and  drawing  the  wiro 
through  with  the  pliers  or  a  hand  vice,  or  by  a  reel  moved  by  a 
winch  handle. 

DRAWING  METAL  TUBES. — The  perfection  of  tubes  is  mainly  de- 
pendent on  the  drawing  process,  conducted  ill  a  manner  similar  to 
that  employed  for  drawing  wire.  Many  of  the  brass  tubes  for 


328  THE   PRACTICAL   METAL- WORKER'S   ASSISTANT. 

common  purposes,  when  they  have  been  bent  up  and  soldered  edge 
to  edge,  as  in  Fig.  231,  page  294,  are  only  drawn  through  a  hole 
which  makes  them  tolerably  round  and  smooth  externally,  but  leaves 
the  interior  of  the  tubes  in  the  condition  in  which  they  left  the 
fire  after  they  were  soldered,  and  nearly  as  soft  as  at  first. 

The  sliding  tubes  for  telescopes,  and  many  similar  works,  are 
"drawn  inside  and  out,"  and  rendered  very  hard  and  elastic,  by  the 
method  represented  in  Fig.  287,  the  form  of  the  plate  b  being  ex- 
aggerated to  explain  the  shape.  For  example,  the  tube  when  sol- 
dered is  forced  upon  an  accurate  steel  cylinder  or  triblet,  in  doing 
which  it  is  rounded  tolerably  to  the  form  with  a  wooden  mallet,  so 

Figs.  287  288. 


as  to  touch  the  mandrel  in  places ;  the  end  is  set  down  with  the 
hammer  around  the  shoulder  or  reduction  of  the  triblet,  and  on  the 
drawing  tube  and  triblet,  by  means  of  the  loose  key  or  transverse 
piece  a,  through  the  draw-plate  b,  the  tube  becomes  elongated,  and  con- 
tracted close  upon  the  triblet  at  every  part,  as  the  metal  is  squeezed 
between  the  mandrel  and  plate.  The  fluted  tubes  for  pencil-cases, 
such  as  c,  are  drawn  in  this  manner  through  ornamental  plates, 
the  triblets  being  in  general  cylindrical.  Some  of  the  drawn 
tube  called  joint- wire,  is  much  smaller  than  d,  and  is  used  by 
silversmiths  for  hinges  and  joints.  It  is  drawn  upon  a  piece  of 
steel  wire,  which  being  too  small  to  admit  the  shoulder  for  holding 
on  the  tube,  the  latter  is  tapered  off  with  a  file,  and  the  tube  and 
wire  are  grasped  together  within  the  dogs,  and  drawn  like  a  piece 
of  solid  wire.  A  semicircular  channel  is  filed  half-way  in  both 
the  parts  to  be  hinged,  and  short  pieces  of  the  joint- wire  are  sol- 
dered in  each  alternately. 

Triangular,  square,  and  rectangular  brass  tubes  are  in  common 
use  in  France  for  sliding  rules  and  measures.  These  are  made  in 
draw-plates  with  movable  dies,  Fig.  288,  which  admit  of  adjust- 
ment for  size.  The  dies  are  rounded  on  their  inner  edges,  and  are 
contained  in  a  square  frame  with  adjusting  screws,  and  the  whole 
lies  against  a  solid  perforated  plate. 

In  the  general  way,  tubes  of  small  diameters  are  completed  at 
two  draughts — sometimes  three  are  used — and  by  this  time  the 
tube  has  received  its  maximum  amount  of  hardness  ;  therefore  the 
first  thickness  of  the  metal  and  the  diameter  of  the  plates  require 


PROCESSES   DEPENDENT   ON   DUCTILITY.  329 

a  nice  adjustment.  The  tube,  when  finished,  is  drawn  off  the 
triblet  by  putting  the  key  through  the  opposite  extremity  of  the 
same,  and  drawing  tfll  triblet  through  a  brass  collar  which  ex- 
actly fits  it ;  this  thrusts  off  the  tube,  which  will  in  general  be 
almost  perfectly  cylindrical  and  straight,  except  a  trifling  waste  at 
each  end. 

It  requires  a  very  considerable  assortment  of  truly  cylindrical 
triblets  to  suit  all  works ;  and  when  the  tubes  are  used  in  pairs,  or 
to  slide  within  one  another,  as  in  telescopes,  it  calls  for  a  nice  cor- 
respondence or  strict  equality  of  size  between  the  aperture  of  the 
last  draw-plate  and  the  diameter  of  the  triblet  for  the  size  next 
larger ;  and  as  these  holes  are  continually  wearing,  it  requires  good 
management  to  keep  the  succession  in  due  order,  by  making  new 
plates  for  the  last  draught  and  adapting  the  old  ones  to  the  prior 
stages.  Sometimes,  for  an  occasional  purpose,  the  triblet  is  en- 
larged by  leaving  a  tube  upon  it  and  drawing  the  work  thereupon ; 
but  this  is  not  so  well  as  the  turned  and  ground  surface  of  the 
steel  triblet.  ~z — 

Tubes  from  y^  inch  internal  diameter  and  8  or  10  inches  long, 
up .  to  those  of  2  or  3  inches  diameter  and  4  or  5  feet  long,  are 
drawn  vertically  by  means  of  a  strong  chain  wound  on  a  barrel  by 
wheels  and  pinions,  as  in  a  crane.  In  Donkin's  enormous  tube- 
drawing  machine,  which  is  applicable  to  making  tubes,  or  rather 
cylinders,  for  paper-making  and  other  machinery,  as  large  as  26| 
inches  diameter  and  6  J  feet  long,  a  vertical  screw  is  used,  the  nut 
of  which  is  turned  round  by  toothed  wheels  driven  by  six  men  at 
a  windlass. 

All  the  tubes  previously  referred  to  are  made  of  sheet-metals 
turned  up  and  soldered  edge  to  edge,  but  lead  and  thin  pipes  for 
water  and  other  fluids  have  for  a  long  period  been  cast  as  thick 
tubes,  some  20  to  30  Inches  long,  and  extended  to  the  length  of 
10,  12,  or  15  feet  on  triblets,  which  require  to  be  very  exactly 
cylindrical  or  they  cannot  be  withdrawn  from  the  pipes. 

The  brass  tubes  for  the  boilers  of  locomotive  engines  are  now 
similarly  made  by  casting  and  drawing  without  being  soldered,  and 
some  of  these  are  drawn  taper  in  their  thickness. 

The  ductility  of  tin  is  very  great.  It  is  from  the  ordinary  tin 
tube  of  commerce  (which  is  cast  about  2  feet  long,  |  inch  thick, 
and  drawn  out  to  about  10  feet),  out  of  which  is  made  the  col- 
lapsable vessels  for  artists'  oils  and  colors. .  Pieces  3  inches  long 
were  extended  to  36  inches  by  drawing  them  through  ten  draw- 
plates,  which  are  sometimes  placed  in  immediate  succession,  the 
one  to  commence  j  ust  as  the  other  had  finished.  The  tube  seemed 
to  grow  under  the  operation,  and  it  was  thus  reduced,  without  an- 
nealing, from  half  an  inch  thick,  as  cast,  to  the  170th  of  an  inch 
thick,  and  it  was  stretched  fully  sixty  times  in  length.  This  rmxlo 
of  making  the  tubes  of  collapsable  vessels,  has  been  superseded 
by  another,  presenting  far  greater  ingenuity,  and  described  here- 


330 


THE   PRACTICAL   METAL-WORKER  S   ASSISTANT. 


Fie.  289. 


Some  of  the  smallest  tin  tube  of  commerce,  when  removed  from 
the  ten-foot  triblet,  is  drawn  through  smalter  plates  without  any 
triblet  being  used.  This  reduces  the  dianMer,  with  little  change 
of  thickness,  so  that  the  half-inch  tube  becomes  a  nearly  solid  wire, 
measuring  about  £  inch  diameter  externally,  which  is  known  as 
beading,  and  used  to  form  the  raised  ledges  around  tables  and 
counters  covered  with  pewter. 

The  accompanying  sectional  view  gives  the  hydraulic  press,  and 
an  arrangement  for  manufacturing  lead  pipe.  The  principle  is 

claimed  by  Tetham,  Cornell, 
Burr,  and  others.  C  is  the 
hydraulic  cylinder,  and  H 
the  ram  rising  from  it.  A 
cross-head  is  attached  to  the 
hydraulic  cylinder,  and  con- 
nected with  the  upper  cross- 
head  H  by  rods  D  D.  On 
the  top  of  the  ram  a  head- 
block  B  is  placed.  A  foot- 
block  F  is  attached  to  the 
bottom  of  the  lead  cylinder 
L,  and  the  head-block,  the 
foot-block,  and  the  lead  cyl- 
inder are  secured  firmly  to- 
gether by  bolts  T  T.  By 
this  arrangement  the  lead 
"plug"  or  cylinder  L  is 
moved  upwards  by  the  ram 
R  of  the  hydraulic  press. 
To  the  upper  cross-head  H 
the  hollow  piston  P  is  at- 
tached by  bolts  S  S.  The 
die  Q,  placed  at  the  lower 
end  of  the  piston,  hollow 
throughout,  communicates 
with  the  aperture  A  in 
the  upper  cross-head.  The 
movable  core  I,  when  in  use, 
is  firmly  fixed  to  the  head- 
block  of  the  ram  and  ex- 
tends upwards  through  the 
centre  of  the  lead  cylinder, 
and  a  little  above  it,  so  that 

it  is  inserted  through  the  die  Q  at  the  end  of  the  hollow  piston  P. 
The  position  of  the  core  is  regulated  by  means  of  the  set-screws 
V  V,  which  move  the  core  and  set  it  centrally  to  the  die.  When 
all  the  parts  are  thus  arranged  the  lead  cylinder  is  raised  up  to 
the  lower  end  of  the  piston,  the  end  of  the  core  passing  through 
the  die. 


I 

* 

SOLDERING.  331 

The  ram  is  forced  upwards,  carrying  the  cylinder  X  that  con- 
tains the  plug  of  leacl^ly ;  this  cylinder  X.  passes  over  the  hollow 
piston  P.  The  pipe'is  formed  at  the  point  of  pressure  Q,  it  then 
passes  through  the  hollow  piston  and  out  through  the  aperture  A. 


CHAPTER  XIX. 

SOLDERING. 

GENERAL  REMARKS  AND  TABULAR  VIEW. — Soldering  is  the 
process  of  uniting  the  edges  or  surfaces  of  similar  or  dissimilar 
metals  and  alloys  by  partial  fusion.  In  general,  alloys  or  solders 
of  various  and  greater  degrees  of  fusibility  than  the  metals  to  be 
joined,  are  placed  between  them,  and  the  solder  when  fused  unites 
the  three  parts  into  a  solid  mass.  Less  frequently  the  surfaces  or 
edges  are  simply  melted  together  with  an  additional  portion  of  the 
same  metal. 

The  chemical  circumstances  to  be  considered  in  respect  to  solder- 
ing are,  for  the  most  part,  set  forth  in  the  section  on  the  fusibility 
of  alloys,  pages  217  to  220,  to  which  the  reader  is  referred.  It  is 
there  explained  that  the  solders  must  be  necessarily  somewhat  more 
fusible  than  the  metals  to  be  united ;  and  that  it  is  of  primary  im- 
portance that  the  metallic  oxides  apd  any  foreign  matters  be 
carefully  removed,  for  which  purpose  the  edges  of  the  metals  are 
made  chemically  clean,  or  quite  bright,  before  the  application  of 
the  solders  and  heat ;  and  as  during  this  period  their  affinity  for 
oxygen  is  violent,  they  are  covered  with  some  flux  which  defends 
them  from  the  air,  as  with  a  varnish,  and  tends  to  reduce  any  por- 
tion of  oxide  accidentally  ^existing. 

The  solders  are  broadly  distinguished  as  hard  solders  and  soft 
solders  ;  the  former  only  fuse  at  the  red  heat,  and  are  consequently 
suitable  alone  to  metals  and  alloys  which  will  endure  that  tempera- 
ture ;  the  soft  solders  melt  at  very  low  degrees  of  heat,  and  may 
be  used  for  nearly  all  the  metals. 

The  attachment  is  in  every  case  the  stronger  the  more  nearly 
the  metals  and  solders  respectively  agree  in  hardness  and  mallea- 
bility. Thus,  if  twp  pieces,  of  brass  or  copper,  or  one  of  each,  are 
brazed  together,  or  united  with  spelter-solder,  an  alloy  nearly  as 
tough  as  the  brass,  the  work  may  be  hammered,  bent  and  rolled 
almost  as  freely  as  the  same  metals  when  not  soldered,  because  of 
the  nearly  equal  cohesive  strength  of  the  three  parts. 

Lead,  tin,  or  pewter,  united  with  soft  solder,  are  also  malleable 
from  the  near  agreement  of  these  substances  ;  whereas  when  cop- 
per, brass  and  iron  are  soft-soldered,  a  blow  of  the  hammer,  or 
any  accidental  violence,  is  almost  certain  to  break  the  joint  asun- 


332  THE    PRACTICAL    METAL-WOBKEB'S  ASSISTANT. 

der,  so  long  as  the  joint  is  weaker  than  the  metal  generally ;  and 
therefore  the  joint  is  only  safe  when  the  surrounding  metal,  from 
its  thinness,  is  no  stronger  than  the  solder,  so  that  the  two  may 
yield  in  common  to  any  disturbing  cause. 

The  forms  of  soldered  joints  in  the  thin  metals  have  been  figured 
and  explained  in  pages  293  to  296  ;  and  soldered  joints  in  thicker 
works  resemble  the  several  attachments  employed  in  construction 
generally.  When  the  spaces  between  the  works  to  be  joined  are 
wide  and  coarse,  the  fluid  solder  will  probably  fall  out,  simply  from 
the  effect  of  gravity ;  but  when  the  crevices  are  fine  and  close,  the 
solder  will  be  as  it  were  sucked  up  by  capillary  attraction.  All 
soldered  works  should  be  kept  under  motionless  restraint  for  a 
period,  as  any  movement  of  the  parts  during  the  transition  of  the 
solder  from  the  fluid  to  the"  solid  state  disturbs  its  crystallization 
and  the  strict  unity  of  the  several  parts. 

In  hard-soldering,  it  is  frequently  necessary  to  bind  the  works 
together  in  their  respective  positions ;  this  is  done  with  soft  iron 
binding-wire,  which  for  delicate  jewelry  work  is  exceedingly  fine, 
and  for  stronger  works  is  the  twentieth  or  thirtieth  of  an  inch  in 
diameter ;  it  is  passed  around  the  work  in  loops,  the  ends  of  which 
are  twisted  together  with  the  pliers. 

In  soft  soldering,  the  binding  wire  is  scarcely  ever  used,  as  from 
the  moderate  and  local  application  of  the  heat,  the  hands  may  in 
general  be  freely  used  in  retaining  most  thin  works  in  position 
during  the  process.  Thick  works  are  handled  with  pliers  or  tongs 
whilst  being  soft-soldered,  and  they  are  often  treated  much  like 
glue  joints,  if  we  conceive  the  wood  to  be  replaced  by  metal,  and 
the  glue  by  solder,  as  the  two  surfaces  are  frequently  coated  or 
tinned  whilst  separated,  and  then  rubbed  together  to  distribute  and 
exclude  the  greater  part  of  the  solder. 

The  succeeding  "  Tabular  View  of  the  Processes  of  Soldering" 
may  be  considered  as  the  index,  which  refers  to  the  ordinary 
methods  of  soldering  most  metals. 


TABULAR  VIEW 

OF    THE    PROCESSES    OF    SOLDERING. 


Note. — To  avoid  continual  repetition,  references  are  made  to  the 
pages  of  this  volume  which  illustrate  the  respective  sub- 
jects, and  also  to  the  lists  on  the  opposite  page,  in  which 
some  of  the  solders,  fluxes,  and  modes  of  applying  heat 
are  enumerated. 


SOLDERING.  333 

• 

HARD-SOLDERING.     339. 

Applicable  to  nearly  all  metals  less  fusible  than  the  solders ;  the' 
modes  of  treatment  are  nearly  similar  throughout. 

The  hard  solders  most  commonly  used  are  the  spelter  solders,  and  silver 
solders.  The  general  flux  is  borax,  marked  A,  on  page  334 ;  and  the 
modes  of  heating  are  the  naked  fire,  the  furnace  or  muffle,  and  the  blow- 
pipe marked  a.  b.  g. 

Note. — The  examples  commence  with  the  solders  (the  least  fusible 
first),  followed  by  the  metals  for  which  they  are  commonly 
employed. 

Fine  Gold,  laminated  and  cut  into  shreds,  is  used  as  the  solder 
for  joining  chemical  vessels  made  of  platinum. 

Silver  is  by  many  considered  as  much  the  best  solder  for  German 
silver. 

Copper  in  shreds,  is  sometimes  similarly  used  for  iron. 

Gold  solders  laminated,  are  used  for  gold  alloys.  See  191-193 
and  341. 

Spelter  solders  granulated  whilst  hot,  are  used  for  iron,  copper, 
brass,  gun-metal,  German  silver,  etc.,  184,  339-341. 

Silver  solders  laminated,  are  employed  for  all  silver  works  and 
for  common  gold  work,  also  for  German  silver,  gilding  metal,  iron, 
steel,  brass,  gun-metal,  etc.,  when  greater  neatness  is  .required  than 
is  obtained  with  spelter-solder.  199  and  341. 

White  or  button  solders  granulated,  are  employed  for  the  white 
alloys  called  button  metals;  they  were  introduced  as  cheap  substi- 
tutes for  silver-solder.  188. 

SOFT-SOLDERING.     341. 

Applicable  to  nearly  all  the  metals;  the  modes  of  treatment  very 
different. 

The  soft-solder  mostly  used,  is  2  parts  tin  and  1  part  lead;  some- 
times from  motives  of  economy  much  more  lead  is  employed,  and  1J  tin 
to  1  lead  is  the  most  fusible  of  the  group  unless  bismuth  is  used.  The 
fluxes  B  to  G,  and  the  modes  of  heating  a  to  i,  are  all  used  with  the 
soft-solders. 


Note. — The  examples  commence  with  the  metals  to  be  soldered. 
Thus  in  the  list  Zinc,  8,  C,  /,  implies,  that  zinc  is  soldered 
with  No.  8  alloy,  by  the  aid  of  the  muriate  or  chloride  of 
zinc,  and  the  copper  bit.  Lead,  4  to  8,  F,  d,  e,  implies 
that  lead  is  soldered  with  alloys  varying  from  No.  4  to  8, 
and  that  it  is  fluxed  with  tallow,  the  heat  being  applied 
by  pouring  on  melted  solder,  and  the  subsequent  use  of 
the  heated  iron  not  tinned ;  but  in  general  one  only  of  the 
modes  of  heating  is  selected,  according  to  circumstances. 


334 


THE   PRACTICAL   METAL-WOBKER'S  ASSISTANT. 


Iron,  cast-iron  and  steel,  8,  B,  D,  if  thick  heated  by  a,  b,  or  c, 
and  also  by  g.  344. 

Tinned  iron,  8,  C,  D,/     342-3. 

Silver  and  Gold  are  soldered  with  pure  tin  or  else  with  8,  E,  a, 
g,  or  h. 

Copper  and  many  of  its  alloys,  namely,  brass,  gilding  metal,  gun- 
metal,  etc.,  8,  B,  C,  D ;  when  thick  heated  by  a,  b,  c,  e,  er  g,  and 
when  thin  by/  or  g.  343-5. 

Speculum  metal,  8,  B,  C,  D,  the  heat  should  be  most  cautiously 
applied,  the  sand-bath  is  perhaps  the  best  mode. 

Zinc,  8,  C,/.     344. 

Lead  and  lead  pipes,  or  ordinary  plumbers'  work,  4  to  8,  F,  d, 
or  e,  342. 

Lead  and  tin  pipes,  8,  B|&  G  mixed,  g,  and  also  /.     345. 

Brittannia  metal,  8,  C,  D,  g. 

Pewters,  the  solders  must  vary  in  fusibility  according  to  the  fusi- 
bility of  the  metal ;  generally  G  and  i  are  used,  sometimes  also  G 
and  g,  or/.  345-6. 

Tinning  the  metals,  and  washing  them  with  lead,  zinc,  etc. 
S46-.7 

SOLDERING  PER  SE,  OR  BURNING  TOGETHER.  347. 

Applicable  to  some  few  of  the  metals  only,  and  which  in  general 
require  no  flux. 

Iron  and  brass,  etc.,  are  sometimes  burned,  or  united  by  partial 
fusion,  by  pouring  very  hot  metal  over  or  around  them,  d.  347-9. 

Lead  is  united  without  solder,  by  pouring  on  red-hot  lead,  and 
employing  a  red-hot  iron,  d,  e,  347,  and  also  by  the  autogenous 
process,  page  350. 


ALLOYS  AND  THEIR  MELTING  HEATS.* 
No.  1.  1  Tin,  25  Lead  558  Fahr. 

2.  1     _    10     —  541     — 

3.  1     —    6      —  511     — 


4.  1  — 

5.  1  — 

6.  1  — 

7.  11  - 

8.  2  — 

9.  3  — 

10.  4  — 

11.  5  — 

12.  6  —    1      — 

13.  4  Lead,  4    Tin,  1  Bisr 

14.  3 

15.  2 

16.  1 

17.  2 

18.  3 


—    5 


432  — 

441  — 

370  — 

334  — 

340  — 

356  — 

365  — 

378  — 

381  — 

Uh320  — 

310  — 

292  — 

254  — 

236  — 

202  — 


Note. — By  the  addition  of  3  parts  of  mer- 
cury to  No.  18  it  melts  at  122°  F., 
and  may  be  used  for  anatomical 
injections,  and  for  stopping  teeth. 


FLUXES. 

A.  Borax.     339. 

B.  Sal-ammoniac,  or  mur.  of  ammo'a.  343-4. 

C.  Muriate,  or  chloride  of  zinc.     344. 

D.  Common  resin. 

E.  Venice  turpentine.  , 

F.  Tallow.     342. 

G.  Gallipoli  oil,  a  common  sweet  oil.     346. 

MODES  OP  APPLTIKG  HEAT. 

a.  Naked  fire.     335-6. 

b.  Hollow  furnace  or  muffle.     335. 

c.  Immersion  in  melted  solder.     344. 

d.  Melted  solder  or  metal  poured  on.  341-7. 

e.  Heated  iron  not  tinned.     342. 

f.  Heated  copper  tool,  tinned.     342-9. 

g.  Blowpipe  flame  336  to  339,  341,  345,  350. 
A.  Flamo  alono,  generally  alcohol. 

i.  Stream  of  heated  air.     346. 


*  The  table  by  H.  GAUI-THIER  DE  CLAPBRT,  from  which  the  present  extract  is 


SOLDERING.  335 

THE  MODES  OF  APPLYING  HEAT  IN  SOLDERING. — The  modes 
of  heating  works  for  soldering  are  extremely  varied,  and  depend 
jointly  upon  the  magnitude  of  the  objects,  the  general  or  local 
manner  in  which  they  are  to  be  soldered,  and  the  fusibility  of  the 
solders.  It  appears  to  be  now  desirable  to  advert  to  such  of  the 
modes  of  applying  heat  enumerated  in  the  tabular  view,  as  are  of 
more  general  application,  leaving  the  modes  specifically  employed 
in  heating  works  to  their  respective  sections. 

In  hard-soldered  works,  the  fires  bear  a  general  resemblance  to 
those  employed  in  forging  iron  and  steel,  and  already  described ; 
in  fact,  the  blacksmith's  forge  is  frequently  used  for  brazing, 
although  the  process  is  injurious  to  the  fuel  as  regards  its  ordinary 
use.  Coppersmiths,  silversmiths,  and  others,  use  a  similar  hearth, 
but  which  stands  further  away  from  the  upright  wall,  so  as  to 
allow  of  the  central  parts  of  large  objects  being  soldered;  the 
blows  are  always  worked  by  the  foot,  either  by  a  treadle,  as  in 
Fig.  42,  p.  93,  or  more  commonly  by  a  chain  from  the  rocking- 
staff  terminating  in  a  stirrup. 

Some  parts  of  the  remarks  on  forging  iron  and  steel,  p.  86  to 
94,  and  also  of  those  on  hardening  and  tempering  steel,  147  and 
152,  refer  to  similar  applications  of  heat  to  those  required  in  sol- 
dering. 

The  brazier's  hearth  for  large  and  long  works,  is  a  flat  plate  of 
iron,  about  four  feet  by  three,  which  stands  in  the  middle  of  the 
shop  upon  four  legs :  the  surface  of  the  plate  serves  for  the  support 
of  long  tubes  and  works  over  the  central  aperture  in  the  plate 
which  contains  the  fuel,  and  measures  about  two  feet  by  one,  and 
five  or  six  inches  deep.  The  revolving  fan  is  commonly  used  for 
the  blast,  and  the  tuyere  irons,  which  have  larger  apertures  than 
usual,  are  fitted  loosely  into  grooves  at  the  ends,  to  admit  of  easy 
renewal,  as  they  are  destroyed  rather  quickly.  The  fire  is  some- 
times used  of  the  full  length  of  the  hearth,  but  is  more  generally 
contracted  by  a  loose  iron  plate ;  occasionally  two  separate  fires 
are  made,  or  the  two-blast  pipes  are  used  upon  one.  The  hood  is 
suspended  from  the  ceiling,  with  counterpoise  weights,  so  as  to  be 
raised  or  depressed  according  to  the  magnitude  of  the  works ;  and 
it  has  large  sliding  tubes  for  conducting  the  smoke  to  the  chimney. 

Furnaces  are  occasionally  used  in  soldering,  or  the  common  fire 
is  temporarily  converted  into  the  condition  of  a  furnace  from  being 
built  hollow,  or  by  the  insertion  of  iron  tubes  or  muffles,  amidst 
the  ignited  fuel,  as  already  explained  in  reference  to  forging  and 
hardening.  For  want  of  any  of  these  means,  the  amateur  may 
use  the  ordinary  grate,  or  it  is  better  to  employ  a  brazie*  or  chaf- 

derived,  enumerates  102  different  alloys  intended  to  be  naed  for  the  safety 
plugs  of  steam  boilers,  in  order  that  the  fusion  of  the  plug,  and  the  conse- 
quent escape  of  the  water,  may  occur  when  the  steam  exceeds  any  predeter- 
mined pressure,  dependent  on  thermometrio  temperature.  See  LA  Diction- 
naire  de  I' Industrie  Manufacturitre,  Commerciale,  et  Ayricole,  par  A.  Baudrimont, 
Blanqui  aln(  et  autres.  Paris,  1833.  Vol.  I.,  p.  326. 


336  THE  PRACTICAL   METAL- WORKER'S  ASSISTANT. 

ing  dish  containing  charcoal,  and  urged  with  hand-bellows  blown 
by  an  assistant,  as  then  both  hands  are  at  liberty  to  manage  the 
work  and  fuel. 

Fresh  coals  are  highly  improper  for  soldering,  on  account  of  the 
sulphur  they  always  contain ;  the  best  fuel  is  charcoal,  but  in  gen- 
eral coke  or  cinders  are  used.  Lead  is  equally  as  prejudicial  to 
the  fire  in  soldering,  as  it  is  in  welding  iron  and  steel,  or  in  forg- 
ing gold,  silver,  or  copper ;  as  the  lead  readily  oxidizes  and  at- 
taches itself  to  the  metals  that  are  being  soldered  or  welded,  pre- 
venting the  union  of  the  parts,  and  in  almost  all  cases  rendering 
the  metals  brittle  and  unserviceable. 

There  are  many  purposes  in  the  arts  which  require  the  applica- 
tion of  heat,  having  the  intensity  of  the  forge  fire  or  of  the 
furnace,  but  with  the  power  of  observation,  guidance,  and  defini- 
tion of  the  artist's  pencil.  These  conditions  are  mos~t  efficiently 
obtained  by  the  blowpipe,  an  instrument  by  which  a  stream  of  air 
is  driven  forcibly  through  a  flame,  so  as  to  direct  it  either  as  a 
well-defined  cone,  or  as  a  broad  jet  of  flame,  against  the  object  to 
be  heated,  which  is  in  many  cases  supported  upon  charcoal,  by 
way  of  concentrating  the  heat. 

The  blowpipe  is  largely  used — namely,  in  soldering,  in  harden- 
ing and  tempering  small  tools,  in  glass-blowing  for  philosophical 
instruments  and  toys,  in  glass-pinching  with  metal  moulds  niade 
like  pliers,  in  enameling,  and  by  the  chemist  and  mineralogist,  as 
an  important  means  of  analysis  ;  the  instrument  has  consequently 
received  very  great  attention  both  from  artisans  and  distinguished 
philosophers. 

Most  of  the  blowpipes  are  supplied  with  common  air,  and  gen 
erally  by  the  respiratory  organs  of  the  operator ;  sometimes  by 
bellows  moved  with  the  foot,  by  vessels  in  which  the  air  is  con- 
densed by  a  syringe,  or  by  pneumatic  apparatus  with  water  pres- 
sure. In  some  few  cases  oxygen  or  hydrogen,  or  the  same  gases 
when  mixed  are  employed ;  they  are  little  used  in  the  arts. 

The  ordinary  blowpipe  is  a  light  conical  brass  tube,  about  10  or 
12  inches  long,  from  one-half  to  one-fourth  of  an  inch  diameter  at 
the  end  for  the  mouth,  and  from  one-sixteenth  to  one-fiftieth  at  the 
aperture  or  jet ;  the  end  is  bent  as  a  quadrant,  that  the  flame  may 
be  immediately  under  observation. 

Fig.  290  represents  the  same  instrument  when  fitted  with  a  ball 
for  collecting  the  condensed  vapor  from  the  lungs ;  it  is  seen  by 
the  enlarged  section,  Fig.  291,  that  the  tube  is  discontinuous,  and 
any  moisture  within  it,  proceeding  in  the  direction  of  the  arrow,  is 
arrested  in  the  ball.  There  are  several  other  blowpipes  for  the 
mouth,  with  various  contrivances,  such  as  a  series  of  apertures  of 
different  diameters,  joints  for  portability,  and  for  placing  the  jet  at 
different  angles,  and  projecting  parts  to  support  the  instrument 
upon  the  table ;  but  none  of  these  are  in  common  use. 

The  lungs  may  be  used  for  the  blowpipe  with  much  more  effect 
than  might  be  expected,  and  with  a  little  practice  a  constant  stream 


SOLDERING. 


337 


may  be  maintained  for  many  minutes,  if  the  cheeks  are  kept  fully 
distended  with  wind,  so  that  their  elasticity  alone  shall  serve  to 
impel  a  part  of  the  air,  whilst  the  ordinary  breathing  is  carried  on 
through  the  nostrils  for  a  fresh  supply. 

The  most  intense  heat  of  the  common  blowpipe  is  that  o£  the 
pointed  flame ;  with  a  thick  wax  candle,  and  a  blowpipe  with  a 
small  aperture  placed  slightly  within  the  flame,  the  mineralogist 
succeeds  in  melting  small  fragments  of  all  the  metals,  when  they 
are  supported  upon  charcoal  and  exposed  to  the  extreme  point  of 
the  inner  or  blue  cone,  which  is  the  hottest  part  of  the  flame ;  that 
is,  fragments  of  all  metals  which  do  not  require  the  oxhydrogen 
blowpipe  invented  by  Dr.  Hare  of  Philadelphia. 

Larger  particles,  requiring  less  heat,  are  brought  somewhat 
nearer  to  the  candle,  so  as  to  receive  a  greater  portion  of  the  flame ; 
and  when  a  very  mild  degree  of  heat  is  needed,  the  object  is  re- 
moved further  away,  sometimes,  as  in  melting  the  fluxes  prepara- 
tory to  soldering,  even  to  the  stream  of  hot  air  beyond  the  point  of 
the  external  yellowish  flame. 

The  first,  or  the  silent  pointed  flame,  is  used  by  the  chemist  and 
mineralogist  for  reducing  the  metallic  oxides  to  the  metallic  state, 
and  is  called  the  deoxidizing  flame ;  the  second,  or  the  noisy  brush- 
like  flame,  is  less  intense,  and  is  called  the  oxidizing  flame. 

The  artizan  employs  in  soldering  a  much  larger  flame  than  the 
chemist,  namely,  that  of  a  lamp  the  wick  of  which  is  from  a  quarter 
to  one  inch  diameter;  this  must  be  plentifully  supplied  with  oil; 
the  blowpipe  in  such  cases  is  selected  with  a  large  aperture ;  it  is 
blown  vigorously,  and  held  a  little  distant  from  the  flame,  so  as  to 
spread  it  in  a  broad  stream  of  light,  extending  over  a  large  surface 
of  the  work,  which  is  in  most  cases  supported  upon  charcoal. 
When  any  minute  portion  alone  is  to  be  heated,  the  pointed  flame 
is  used  with  a  milder  blast  of  air  and  a  decreased  distance. 


Figs.  290 


293 


Fig.  292  is  an  arrangement,  the  use  of  which  is  attended  with 
no  fatigue  to  the  operator.     A  stream  of  air  from  a  pair  of  bellows 
directs  a  gas  flame  through  a  trough  or  shoot,  the  third  of  a  cylin- 
drical tube  placed  at  a  small  angle  below  the  flame.     Instead  of  a 
22 


338  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

charcoal  support,  they  employ  a  wooden  handle,  upon  which  is  fixed 
a  flat  disk  of  sheet-iron,  about  three  or  four  inches  diameter,  covered 
with  a  matting  of  waste  fragments  of  binding  wire,  entangled  to- 
gether and  beaten  into  a  sheet,  about  three-eighths  or  half  an  inch 
thick ;  some  few  of  the  larger  pieces  of  wire  extend  round  the  edge 
of  the  disk  to  attach  the  remainder.  The  work  to  be  soldered  is 
placed  upon  the  wire,  which  becomes  partially  red-hot  from  the 
flame,  and  retains  the  heat  somewhat  as  the  charcoal,  but  without 
the  inconvenience  of  burning  away,  so  that  the  broad  level  surface 
is  always  maintained.  Small  cinders  are  frequently  placed  upon 
the  tool,  either  instead  of,  or  upon  the  wire. 

Sometimes,  as^in  Fig.  293,  the  gas  pipe  is  surmounted  by  a 
square  hood,  open  at  both  ends,  and  two  blast-pipes  are  directed 
through  it ;  the  latter  arrangement  is  used  by  the  makers  of  glass 
toys  and  seals ;  these  are  pinched  in  moulds  something  like  bullet- 
moulds  ;  the  devices  on  the  seals  are  produced  by  inserting  in  the 
moulds  dried  casts,  made  in  plaster  of  Paris. 

Makers  of  thermometers  and  other  philosophical  instruments 
generally  use  a  table  blowpipe,  with  a  shallow  oval,  or  rather  a 
kidney-shaped  lamp,  Fig.  294,  with  a  loop  placed  lengthways  upon 
the  short  diameter  for  holding  the  cotton,  which  is  sometimes  an 
inch  long  and  half  an  inch  wide.  The  wick  is  plentifully  supplied 
with  tallow  or  hog's  lard,  and  a  furrow  is  made  through  it  with  a 
wire  to  afford  a  free  passage  for  the  blast  from  the  fixed  nozzle,  by 
the  size  of  which,  and  its  distance  from  the  flame,  the  latter  is  made 
to  assume  the  pointed  or  brush-like  character.  This  lamp  is  more 
cleanly,  and  emits  less  smell  than  those  supplied  with  oil ;  any 
overflow  of  the  tallow  is  caught  in  the  outer  vessel  or  tray,  ancl 
when  cold,  the  fat  solidifies.  The  forge,  Fig.  42,  page  93,  has  also 
a  blowpipe  and  lamp  to  enable  it  to  be  applied  to  the  arts  in  a  similar 
manner,  and  a  very  cheap  table  blowpipe  is  described  by  Dr. 
Michael  Faraday,  in  his  "Chemical  Manipulation,"  page  120-169. 

Many  blowpipes  have  been  invented  for  the  employment  of 
oxygen  and  hydrogen;  the  mixed'  gases  were  first  used  by  Dr. 
Hare,  of  Philadelphia,  who  has  been  followed  in  various  ways  by 
many  others.  The  construction  and  management  of  nearly  all  the 
blowpipes  are  described  in  Dr.  Faraday's  "  Chemical  Manipula- 
tion," 1830,  pages  107  to  123.  Also  in  "A  Practical  Treatise  on  the 
Use  of  the  Blowpipe,"  by  his  talented  countryman,  Dr.  Sheridan 
Muspratt,  now  of  Liverpool,  but  formerly  of  Dublin.  Two  subse- 
quent modifications  of  gas  blowpipes  which  have  been  invented  for 
the  workshop,  will  alone  be  here  described,  namely,  the  Workshop 
Blowpipe,  intended  for  soldering,  hardening,  and  other  purposes ; 
and  the  Count  de  Richemont's  Airo-hydrogen  Blowpipe. 

The  general  form  of  the  "  workshop  blowpipe"  is  that  of  a  tube 
open  at  the  one  end,  and  supported  on  trunnions  in  a  wooden 
pedestal,  so  that  it  may  be  pointed  vertically,  horizontally,  or  at 
any  angle  as  desired.  Common  street  gas  is  supplied  through 
the  one  hollow  trunnion,  and  it  escapes  through  an  anmdar  open- 


SOLDERING.  339 

ing ;  whilst  oxygen  gas,  or  more  usually  common  air,  is  admitted 
through  the  other  trunnion  which  is  also  hollow,  and  is  discharged 
in  the  centre  of  the  hydrogen  through  a  central  conical  tube ;  the 
magnitude  and  intensity  of  the  flame  being  determined  by  the  rela- 
tive quantities  of  gas  and  air,  and  by  the  greater  or  less  protru- 
sion of  the  inner  cone,  by  which  the  annular  space  for  the  hydro- 
gen is  contracted  in  any  required  degree. 

From  amongst  numerous  other  small  applications  of  heat,  a  port- 
able blowpipe  furnace  may  be  noticed ;  it  consists  of  a  lump  of 
pumice-stone  three  or  four  inches  diameter,  scooped  out  like  a  pan 
or  crucible,  and  filled  with  small  fragments  of  charcoal ;  sometimes 
a  conical  perforated  cover  is  added :  the  inside  may  be  intensely 
ignited,  whilst  the  slow  conducting  power  of  the  pumice-stone 
guards  the  hand  from  inconvenient  heat. 

EXAMPLES  OF  HARD  SOLDERING.— It  was  mentioned  in  the 
tabular  view  that  the  several  works  united  with  hard-solders  receive 
nearly  the  same  treatment ;  a  few  examples  will  therefore  serve 
to  convey  a  general  idea  of  hard-soldering;  a  process  commonly 
attended  with  some  risk  of  partially  melting  the  works,  because 
the  fusing  points  of  the  metals  and  their  respective  solders  often 
approach  very  nearly  together. 

Several  of  the  hard  solders  contain  zinc,  which  appears  to  be 
useful  in  different  ways :  first  it  increases  their  fusibility ;  in  cases 
where  the  solder  cannot  be  seen  it  serves  as  an  index  to  denote 
the  completion  of  the  process,  for  when  the  solder  is  melted  the 
zinc  volatilizes,  and  burns  with  the  well-known  blue  flame ;  and  as 
at  this  moment  some  of  the  zinc  is  consumed,  the  alloy  left  behind 
becomes  tougher,  and  more  nearly  approaches  to  the  condition  of 
the  metal  which  it  is  desired  to  unite.  The  zinc  may  be  therefore  con- 
sidered to  act  as  a  flux,  and  so  likewise  does  the  arsenic  occasionally 
introduced  into  the  gold  and  silver  solders,  as  the  arsenic  is  for  the 
most  part  lost,  between  the  processes  of  making  and  using  the 
solders ;  but  this  metal  being  of  a  noxious  quality,  it  is  but  little 
resorted  to,  and  besides,  it  renders  the  other  metals  very  brittle. 

In  every  case  of  soldering,  a  general  regard  to  cleanliness  in  the 
manipulation  is  important,  and  for  the  most  part  the  edges  of  the 
metals  are  filed  or  scraped  prior  to  their  being  soldered,  as  before 
observed ;  in  those  cases  in  which  the  red-heat  is  employed,  filing 
or  scraping  are  less  imperative,  as  any  greasy  or  combustible  mat- 
ters are  burned  away,  and  the  borax  has  the  property  of  combin- 
ing with  nearly  all  the  metallic  oxides  and  earthy  bases,  thereby 
cleansing  the  edges  of  the  metals  should  that  proceeding  have  been 
previously  omitted. 

The  works  in  copper,  iron,  brass,  etc.,  having  been  prepared 
for  brazing  (or  soldering  with  a  fusible  brass),  and  the  joints 
secured  in  position  by  binding  wire  where  needful,  the  granulated 
spelter  and  pounded  borax  are  mixed  in  a  cup  with  a  very  little 
water,  and  spread  along  the  joint  by  a  slip  of  sheet  metal  or  a 
small  spoon. 


340  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

The  work,  if  sufficiently  large,  is  now  placed  above  the  clear 
fire,  first  at  a  small  distance  so  as  gradually  to  evaporate  the  mois- 
ture, and  likewise  to  drive  off  the  water  of  crystallization  of  the 
borax ;  during  this  process  the  latter  boils  up  with  the  appearance 
of  froth  or  snow,  and  if  hastily  heated  it  sometimes  displaces  the 
solder.  The  heat  is  now  increased,  and  when  the  metal  becomes 
faintly  red,  the  borax  fuses  quietly  like  a  glass ;  shortly  after,  that 
is  at  a  bright  red,  the  solder  also  fuses,  the  indication  of  which  is 
a  small  blue  flame  from  the  ignition  of  the  zinc.  Just  at  this  time 
some  works  are  tapped  slightly  with  the  poker  to  put  the  whole 
in  vibration,  and  cause  the  solder  to  run  through  the  joint  to  the 
lower  surface,  but  generally  the  solder  flushes,  or  is  absorbed  in 
the  joint,  and  nearly  disappears  without  the  necessity  for  tapping 
the  work. 

It  is  of  course  necessary  to  apply  the  heat  as  uniformly  as  possi- 
ble, by  moving  the  work  about  so  as  to  avoid  melting  the  object 
as  well  as  the  solder;  the  work  is  withdrawn  from  the  fire  as  soon 
as  the  solder  has  flushed,  and  when  the  latter  is  set,  the  work  may 
be  cooled  in  water  without  mischief. 

Tubes  are  generally  secured  by  loops  of  binding  wire  twisted  to- 
gether with  the  pliers ;  and  those  soldered  upon  the  open  fire  are 
almost  always  soldered  from  within,  as  otherwise  the  heat  would 
have  to  be  transmitted  across  the  tube  with  greater  risk  of  melting 
the  work,  air  being  a  bad  conductor  of  heat ;  it  is  necessary  to  look 
through  the  tube  to  watch  for  the  melting  of  the  solder.  Long  tubes 
are  rested  upon  the  flat  plate  of  the  brazier's  hearth,  and  portions 
equal  to  the  extent  of  the  fire  are  soldered  in  succession.  The  com- 
mon tubes  for  gas-works,  bedsteads,  and  numerous  other  purposes, 
are  soldered  from  the  outside  ;  but  this  is  done  in  short  furnaces 
open  at  both  ends  and  level  with  the  floor,  by  which  the  heat  is 
applied  more  uniformly  around  the  tubes. 

"Works  in  iron  require  much  less  precaution  in  point  of  the  heat, 
as  there  is  little  or  no  risk  of  fusion ;  thus  in  soldering  the  spiral 
wires  to  form  the  internal  screw  within  the  boxes  of  ordinary  tail 
vices,  the  work  is  coated  with  loam,  and  strips  of  sheet  brass  are 
used  as  solder ;  the  fire  is  urged  until  the  blue  flame  appears  at  the 
end  of  the  tube,  when  the  fusion  is  complete ;  the  work  is  with- 
drawn from  the  fire  and  rolled  backwards  and  forwards  on  the 
ground  to  distribute  the  solder  equally  at  every  part.  Other  com- 
mon works  in  iron,  such  as  locks,  are  in  like  manner  covered  with 
loam  to  prevent  the  iron  from  scaling  off. 

Sheet  iron  may  be  soldered  by  filings  of  soft  cast-iron,  applied 
in  the  usual  way  of  soldering  with  borax,  which  has  been  gradually 
dried  in  a  crucible  and  powdered,  and  a  solution  of  sal-ammoniac. 

The  finer  works  in  iron  and  steel,  those  in  the  light-colored 
metals  generally,  and  also  the  works  in  brass  which  are  required 
to  be  very  neatly  done,  are  soldered  with  silver-solder.  From  the 
superior  fusibility  of  silver-solder,  and  from  its  combining  so  well 
with  the  different  metals  without,  "  gnawing  them  or  eating  them 


%  SOLDERING.  341 

away"  or  wasting  part  of  the  edges  of  the  joints,  silver-solder  is 
very  desirable  for  a  great  many  cases ;  and  from  the  more  careful 
and  sparing  manner  in  which  it  is  used,  many  objects  require  but 
little  or  no  finishing  subsequently  to  the  soldering,  so  that  the 
more  expensive  solder  is  not  only  better,  but  likewise  in  reality 
more  economical. 

The  practice  of  silver-soldering  is  essentially  the  same  as  brazing. 
The  joint  is  first  moistened  with  borax  and  water;  the  solder 
(which  is  generally  laminated  and  cut  into  little  squares  with  the 
shears)  is  then  placed  on  the  joint  with  forceps.  In  heating  the 
work  additional  care  is  given  not  to  displace  the  solder ;  and  for 
which  reason  some  persons  boil  the  borax,  or  drive  off  its  water  of 
crystallization  at  the  red  heat,  then  pulverize  it  and  apply  it  in  the 
dry  state  along  with  the  solder ;  others  fuse  the  borax  upon  the 
joint  before  putting  on  the  solder. 

Numerous  small  works  united  with  the  hard-solders,  such  as 
mathematical  and  drawing  instruments,  buttons,  and  jewelry,  are 
soldered  with  the  blowpipe ;  in  almost  all  cases  the  work  is  sup- 
ported upon  charcoal,  and  sometimes  for  the  greater  concentration 
of  the  heat  it  is  also  covered  with  charcoal.  The  management  of 
the  blowpipe  having  been  explained,  it  is  only  necessary  to  add 
that  the  magnitude  and  shape  of  the  flame  are  proportioned  to  those 
of  the  works. 

In  soldering  gold  and  silver,  the  borax  is  rubbed  with  water 
upon  a  slate  to  the  consistence  of  cream,  and  is  laid  upon  the  work 
with  a  camel's-hair  pencil,  and  the  solders,  although  generally  lam- 
inated, are  also  drawn  into  wire,  or  filed  into  dust ;  but  it  will  be 
remembered  the  more  minute  the  particles  of  the  granulated  metals, 
the  greater  is  the  degree  of  heat  required  in  fusing  them. 

In  many  of  the  jewelry  works  the  solder  is  so  delicately  applied 
that  it  is  not  necessary  to  file  or  scrape  off  any  portion,  none  being 
in  excess,  and  the  borax  is  removed  by  immersing  the  works  in 
the  various  pickling  and  coloring  preparations  to  be  adverted  to. 

EXAMPLES  OF  SOFT-SOLDERING. — The  plumbers'  sealed-solder, 
2  parts  lead  and  1  of  tin,  melts  at  about  440°  F. ;  the  usual  or  fine 
tin-solder,  2  parts  tin  and  1  of  lead,  melts  at  340° ;  and  the  bismuth- 
solders  at  from  250°  to  270°:  the  modes  of  applying  the  heat  con- 
sequently differ  very  much,  as  will  be  shown. 

The  soft-solders  are  prepared  in  different  forms  suited  to  the  na- 
ture of  the  various  works ;  No.  5,  p.  334,  the  plumbers'-solder,  is 
cast  in  iron  moulds  into  triangular  ingots  measuring  from  1  to  6 
superficial  inches  in  the  section.  No.  8,  the  fine  tin  solder,  is  cast 
in  cakes  about  4  by  6  inches,  and  £  to  £  inch  thick ;  and  this  and 
the  more  fusible  kinds,  are  trailed  from  the  ladle  upon  an  iron  plate 
or  flat  stone,  to  make  slight  bars,  ribbons,  and  even  threads,  that 
the  magnitude  of  the  solder  may  be  always  proportioned  to  the 
magnitude  and  circumstances  of  the  work. 

It  is  very  essential  that  all  soft-soldered  joints  should  be  parti--u- 
larly  clean  and  free  from  metallic  oxides ;  and,  except  where  oil  is 


342  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT* 

exclusively  used  as  the  flux,  greasy  matters  should  be  avoided,  as 
they  prevent  the  ready  attachment,  of  the  aqueous  fluxes.  It  is 
therefore  usual  with  all  the  metals,  except  clean  tinned  plate,  and 
clean  tin  alloys,  to  scrape  the  edges  immediately  before  the  process, 
so  far  as  the  solder  is  desired  to  adhere. 

Lead  works  are  first  smeared  or  soiled  around  the  intended  joints, 
with  a  mixture  of  size  and  lamp-black,  called  soil,  to  prevent  the 
adhesion  of  the  melted  solder ;  next  the  parts  intended  to  receive 
the  solder  are  scraped  quite  clean  with  the  shave-hook  (a  triangular 
disk  of  steel  riveted  on  a  wire  stem),  and  the  clean  metal  is  then 
rubbed  over  with  tallow.  Some  joints  are  imped,  without  the  em- 
ployment of  the  soldering  iron :  that  is,  the  solder  is  heated  rather 
beyond  its  melting  point,  and  poured  somewhat  plentifully  upon 
the  joint  to  heat  it ;  the  solder  is  then  smoothed  with  the  cloth,  or 
several  folds  of  thick  bed-tick  well  greased,  with  which  the 
superfluous  solder  is  finally  removed. 

Other  lead  joints  are  striped,  or  left  in  ridges,  from  the  bulbous 
end  of  the  plumber's  crooked  soldering-iron,  which  is  heated  nearly 
to  redness,  and  not  tinned ;  the  iron  and  cloth  are  jointly  used  at 
the  commencement,  for  moulding  the  solder  and  heating  the  joint. 
In  this  case  less  solder  is  poured  on,  and  a  smaller  quantity  remains 
upon  the  work  ;  and  although  the  striped-joints  are  less  neat  in  ap- 
pearance, they  are  by  many  considered  sounder  from  the  solder 
having  been  left  undisturbed  in  the  act  of  cooling.  The  vertical 
joints,  and  those  for  pipes,  whether  finished  with  the  cloth  or  iron, 
require  the  cloth  to  support  the  fluid  solder  when  it  is  poured  on 
the  lead. 

Slight  works  in  lead,  such  as  lattices,  requiring  more  neatness 
than  ordinary  plumbing,  are  soldered  with  the  copper-bit  or  copper- 
bolt  represented  in  Figs.  297  and  298 ;  they  are  pieces  of  copper 
weighing  from  three  or  four  ounces  to  as  many  pounds,  riveted 
into  iron  shanks  and  fitted  with  wooden  handles.  All  the  works 
in  tinned  iron,  sheet  zinc,  and  many  of  those  in  copper  and  other 
thin  metals,  are  soldered  with  this  tool,  frequently  misnamed  a 
soldering-iron,  which  in  general  suffices  to  convey  all  the  heat 
required  to  melt  the  more  fusible  solders  now  employed. 


Figs.  295 


298. 


If  the  copper-bit  have  not  been  previously  tinned,  it  is  heated  in 
a  small  charcoal  stove  or  otherwise  to  a  dull  red,  and  hastily  filed 


•T*  SOLDERING.  343 

to  a  clean  metallic  surface ;  it  is  then  rubbed  immediately,  first 
upon  a  lump  of  sal-ammoniac,  and  next  upon  a  copper  or  tin  plate, 
upon  which  a  few  drops  of  solder  have  been  placed ;  this  will  com- 
pletely coat  the  tool ;  it  is  then  wiped  clean  with  a  piece  of  tow, 
and  is  ready  for  use. 

In  soldering  coarse  works,  when  their  edges  are  brought  together, 
they  are  slightly  strewed  with  powdered  resin  contained  in  the  box, 
Fig*  296,  or  it  is  spread  on  the  work  with  a  small  spoon ;  the  cop- 
per-bit is  held  Jin  the  right  hand,  the  cake  of  solder  in  the  left,  and 
a  few  drops  of  the  latter  are  melted  along  the  joint  at  short  intervals. 
The  iron  is  then  used  to  heat  the  edges  of  the  metal,  both  to  fuse 
and  to  distribute  the  solder  along  the  joint,  so  as  to  entirely  fill 
up  the  interval  between  the  two  parts ;  only  a  short  portion  of  the 
joint,  rarely  exceeding  six  or  eight  inches,  is  done  at  once.  Some- 
times the  parts  are  held  in  contact  with  a  broad  chisel-formed  tool, 
or  a  hatchet-stake,  whilst  the  solder  is  melted  and  cooled,  or  a  few 
distant  parts  are  first  tacked  together  or  united  by  a  drop  of  solder 
but  mostly  the  hands  alone  suffice,  without  the  tacking. 

Two  soldering  tools  are  generally  used,  so  that  whilst  the  one  is 
in  the  hand,  the  other  may  be  reheating  in  the  stove ;  the  tempera- 
ture of  the  bit  is  very  important ;  if  it  be  not  hot  enough  to  raise 
the  edges  of  the  metal  to  the  melting  heat  of  the  solder,  it  must  be 
returned  to  the  fire ;  but,  unless  by  mismanagement  it  is  made  too 
hot  and  the  coating  is  burned  off,  the  process  of  tinning  the  bit 
need  not  be  repeated,  it  is  simply  wiped  on  tow,  on  removal  from 
the  fire.  If  the  tool  be  overheated,  it  will  make  the  solder  un- 
necessarily fluid,  and  entirely  prevent  the  main  purpose  of  the 
copper-bit,  which  is  intended  to  act  both  as  a  heating  tool,  and  as  a 
brush,  first  to  pick  up  a  small  quantity  or  drop  from  the  cake  of 
solder  which  is  fixed  upright  in  the  tray,  Fig.  295,  and  then  to 
distribute  it  along  the  edge  of  the  joint. 

The  tool  is  sometimes  passed  only  onct  slowly  along  the  work, 
being  guided  in  contact  with  the  fold  or  ledge  of  the*  metal.  This 
supposes  the  operator  to  possess  that  dexterity  of  hand,  which  is 
abundantly  exhibited  in  many  of  the  best  tin  wares ;  in  these  the 
line  of  solder  is  very  fine  and  regular.  The  soldering-tool  is  then 
thin  and  keen  on  the  edge,  and  the  flux,  instead  of  being  resin,  is 
mostly  the  muriate  of  zinc,  with  which  the  joint  is  moistened  by 
means  of  a  small  wire  or  a  stick  prior  to  the  application  of  the 
heated  tool;  sometimes  the  workman  cools  the  part  just  finished,  by 
blowing  upon  it  as  the  bit  proceeds  in  its  course ;  and  the  iron,  if 
overheated,  is  cooled  upon  a  moistened  rag  placed  in  the  empty 
space  of  the  tray  containing  the  solder. 

Copper  works  are  more  commonly  fluxed  with  powdered  sal- 
ammoniac,  and  so  is  likewise  sheet-iron,  although  some  mix  pow- 
dered resin  and  sal-ammoniac,  others  moisten  the  edges  of  the  work 
with  a  saturated  solution  of  sal-ammoniac,  using  a  piece  of  cane  the 
end  of  which  is  split  into  filaments  to  make  a  stubby  brush,  and 
they  subsequently  apply  resin ;  each  method  has  its  advocates,  but 


344  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

so  long  as  the  metals  are  well  defended  from  oxidation  any  mode 
will  suffice,  and  in  general  management  the  processes  are  the  same. 

Zinc  is  more  difficult  to  solder  than  the  other  metals,  and  the 
joints  are  not  generally  so  neatly  executed ;  the  zinc  seems  to  re- 
move the  coating  of  tin  from  the  copper  soldering-tool ;  this  prob- 
ably arises  from  the  superior  affinity  of  copper  for  zinc  than  for 
tin.  The  flux  sometimes  used  for  zinc  is  sal-ammoniac,  but  the 
muriate  of  zinc,  made  by  dissolving  fragments  of  zinc  in  muriatic 
acid  diluted  with  about  an  equal  quantity  of  water,  is  much  supe- 
rior ;  and  the  muriate  of  zinc  serves  admirably  likewise  for  all  the 
other  metals,  without  such  strict  necessity  for  clean  surfaces  as  when 
the  other  fluxes  are  used. 

The  copper  tool  is  only  applicable  to  thin  metals,  because  it  re- 
quires such  a  degree  of  heat  as  will  allow  it  to  raise  the  temperature 
of  the  work  to  be  joined,  to  the  melting  point  of  the  solder ;  and 
the  excess  of  heat  thus  required  for  stout  metals,  is  apt,  either  to 
burn  off  the  coating  of  solder,  or  to  cause  it  to  be  absorbed  as  a 
process  of  superficial  alloying.  It  requires  some  tact  to  keep  the 
heat  of  the  tool  within  proper  limits  by  means  of  the  charcoal  or 
cinder  fire,  but  with  the  airo-hydrogen  blowpipe,  explained  at  page 
350-2,  it  is  easy  to  maintain  any  required  temperature  for  an 
indefinite  period. 

Thicker  pieces  of  metal,  such  as  the  parts  of  philosophical  ap- 
paratus, gas-fittings,  and  others  which  cannot  be  conveniently 
managed  with  the  copper-bit,  are  first  prepared  by  filling  or  turn- 
ing, and  each  piece  is  then  separately  tinned  in  one  of  the  follow- 
ing ways.  Small  pieces,  immediately  after  being  cleaned  with  the 
file  or  other  tool,  and  without  being  touched  with  the  fingers,  are 
dipped  into  a  ladle  containing  melted  solder,  which  is  covered  with 
a  little  powdered  sal-ammoniac.  The  flux  meets  the  work  before 
it  is  subjected  to  the  heat,  and  the  tinning  is  then  readily  done ; 
sometimes  the  work  is  in  the  first  instance  sprinkled  with  resin, 
or  rubbed  over  with  sal-ammoniac  water ;  the  latter  is  rather  a 
dangerous  practice,  as  the  moisture  is  apt  to  drive  the  melted  metal 
in  the  face  of  the  operator. 

Thin  pieces  of  brass  or  of  copper  alloys,  if  submitted  to  this 
method,  must  be  quickly  dipped,  or  there  is  risk  of  their  being 
attacked  and  partly  dissolved  by  the  solder.  There  is  some  little 
uncertainty  as  to  iron,  and  especially  as  to  steel,  being  well  coated 
by  dipping ;  sometimes  a  forcible  jar  or  a  hard  rub  will  remove 
most  of  the  tin,  and  it  is  therefore  safer  to  rub  these  works  with  a 
piece  of  heated  copper  shaped  like  a  file,  immediately  on  their 
removal  from  the  melted  solder,  which  makes  the  adhesion  more 
certain. 

Larger  pieces  of  metal,  or  those  it  is  inconvenient  to  dip  into  the 
ladle,  are  first  moistened  with  sal-ammoniac  water,  or  dusted  with 
the  dry  powder  or  resin,  and  heated  on  a  clear  fire  either  of  char- 
coal, coke,  or  cinders,  until  the  strip  of  solder  held  against  them 
is  melted  and  adheres  ;  as  the  lowest  heat  should  be  always  used. 


SOLDERING.  345 

Another  cleanly  way  of  applying  the  heat,  and  which  is  also  em- 
ployed in  tempering  tools,  varnishing,  and  cementing,  is  to  make 
red-hot  a  few  inches  of  the  end  of  a  flat  iron  bar  about  two  feet 
long,  to  pinch  it  in  the  vice  by  the  cold  part,  and  to  lay  the  work 
upon  that  spot  which  is  at  a  suitable  temperature  ;  the  work  can 
be  thus  very  conveniently  managed,  especially  as  it  may  be  like- 
wise placed  in  a  good  light. 

Until  the  two  parts  of  the  work  are  thoroughly  tinned,  they 
must  be  well  defended  from  the  air  by  the  flux  to  prevent  oxida- 
tion ;  they  are  next  made  a  trifle  hotter  than  is  required  for  tin- 
ning, and  placed  in  contact  whilst  the  solder  is  quite  fluid,  and  a 
little  additional  solder  is  also  used ;  when  practicable,  the  two  sur- 
faces are  rubbed  together  to  perfect  the  tinning  and  spread  the 
alloy  evenly  through  the  joint ;  the  work  is  then  allowed  to  cool 
under  pressure  applied  by  the  hammer  handle,  the  blunt  end  of  a 
tool,  the  tail- vice,  or  in  any  convenient  manner.  The  stages  of 
this  practice  are  similar  to  those  of  the  carpenter,  who  having 
brushed  the  glue  over  the  two  pieces  of  wood,  rubs  them  together 
and  fixes  them  with  the  hand  screws  until  cold,  as  before  ad- 
verted to. 

Small  works  are  sometimes  united  by  cleaning  the  respective 
surfaces,  moistening  them  with  sal-ammoniac  water,  or  applying 
the  dry  powder  or  resin,  then  placing  between  the  pieces  a  slip  of 
tin-foil,  previously  cleaned  with  emory-paper,  and  pinching  the 
whole  between  a  pair  of  heated  tongs  to  melt  the  foil ;  or,  other 
similar  modifications  combining  heat  and  pressure  are  used. 

Many  workmen  who  are  accustomed  to  the  blowpipe,  as  jewel- 
ers, mathematical  instrument  makers,  and  others,  apply  the  blow- 
pipe with  great  success  in  soft-soldering ;  but  as  the  methods  are 
in  other  respects  similar  to  those  given,  they  do  not  require  partic- 
ular notice,  except  that  in  some  cases  there  is  no  choice  but  to  tie 
the  works  together  with  binding-wire  as  in  hard-soldering ;  but 
the  preference  is  always  given  to  detached  tinning  and  rubbing 
together. 

The  modern  gas-fitters  are  remarkably  expert  in  joining  tin  and 
lead  pipes  with  the  blowpipe ;  they  do  not  employ  the  method  of 
the  plumbers  and  pewterers,  or  the  spigot  and  faucet  joint  sur- 
rounded by  a  bulb  of  solder,  but  they  cut  off  the  ends  of  the  pipes 
with  a  saw,  and  file  the  surfaces  to  meet  in  butt  joints,  in  mitres, 
or  in  T  form  joints  as  required.  In  confined  situations  they  apply 
the  heat  from  one  side  only  with  the  blowpipe  and  rushes ;  they 
employ  a  rich  tin  solder,  with  oil  and  resin  mixed  in  equal  parts 
as  the  flux ;  the  work  looks  like  carpentry  rather  than  soldering. 

The  pewterers  employ  a  very  peculiar  modification  of  the  blow- 
pipe, which  may  be  called  the  hot-air  blast,  and  the  names  for  which 
apparatus  are  no  less  peculiar;  a,  Fig.  299,  being  called  the  //•>'/, 
and  b,  the  gentleman.  The  first  is  a  common  cast-iron  pot  with 
a  close  cover,  containing  ignited  charcoal ;  two  nozzles  leading 
respectively  into  and  from  it,  to  allow  the  passage  of  a  stream  of 


346  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

air,  through  the  pipe  c,  from  bellows  worked  by  the  foot.     The  pew 
ter  wares,  many  of  which  are  circular,  are  placed  on  the  gentleman, 
or  a  revolving-  pedestal,  which  may  be  adjusted  by  the  side  screw  to 
any  height:    the   workmen   dip   the 
Fig.  299.  strip  of  solder  in  a  little  pot  of  oil,  and 

apply  it  to  the  joint  with  the  right 
hand,  whilst  they  slowly  revolve  the 
work  with  the  left.  This,  which  is  a 
very  controllable  application  of  heat, 
includes  in  its  range  a  moderately 
large  extent  of  the  pewterer's  work, 
and  answers  the  purpose  extremely 
well :  by  some,  the  rushes  and  mouth 
blowpipe  are  used  for  circular  as  well 
as  for  other  articles  in  pewter. 
The  pewters  bear  nearly  the  proportion  of  the  alloys  Nos.  8  to 
12,  page  334 :  for  the  less  fusible  containing  most  tin,  the  solder 
No.  8,  or  2  tin  1  lead,  is  used ;  for  the  more  fusible  containing 
most  lead,  the  bismuth  solders,  2  tin  1  lead  1  bismuth,  and  others 
of  similar  low  degrees  of  fusibility,  are  employed.  The  first 
solder  is  called  by  the  pewterers  hard-pale,  the  last  soft-pale,  and  to 
suit  the  pewters  of  intermediate  degrees  of  fusibility,  the  two  are 
mixed  in  variable  proportions  and  called  middling-pale ;  but  the 
table  on  page  334,  and  especially  the  original  from  which  the  18 
terms  there  given  are  extracted,  would  enable  the  solders  to  be 
definitely  proportioned  to  their  respective  metals. 

The  flux  always  used  by  the  pewterers  is  Gallipoli  oil ;  it  is  a 
second  rate  olive  oil,  of  peculiar  quality,  rather  thick,  green,  and 
unfit  for  the  table ;  but  its  selection  requires  judgment. 

Iron,  copper,  and  alloys  of  the  latter  metal,  are  frequently 
coated  with  tin,  and  occasionally  with  lead  and  zinc,  to  present 
surfaces  less  subject  to  oxidation ;  gilding  and  silvering  are  partly 
adopted  from  similar  motives.  As  regards  iron,  the  method  of 
making  the  tinned  plate  is  strictly  a  manufacturing  process,  which 
has  been  slightly  noticed  at  page  200,  and  that  of  covering  iron 
with  zinc,  so  that  it  principally  remains  to  describe  the  ordinary 
method  of  tinning  vessels  and  other  objects  of  copper,  brass,  and 
iron,  after  they  have  been  manufactured,  and  which  is  in  general 
thus  performed. 

Copper  and  brass  vessels  are  first  pickled  with  sulphuric  acid, 
mostly  diluted  with  about  three  times  its  bulk  of  water  ;  they  are 
then  scrubbed  with  sand  and  water,  washed  clean  and  dried ;  they 
are  next  sprinkled  with  dry  sal-ammoniac  in  powder,  and  heated 
slightly  over  the  fire ;  then  a  small  quantity  of  melted  block-tin  is 
thrown  in,  the  vessel  is  swung  and  twisted  about  to  apply  the  tin 
on  all  sides,  and  when  it  has  well  adhered  the  portion  in  excess  is 
returned  to  the  ladle,  and  the  object  is  cooled  in  water.  When 
cleverly  performed  very  little  tin  is  taken  up,  and  the  surface  looks 
almost  as  bright  as  silver:  some  objects  require  to  be  dipped  into 
a  ladle  full  of  tin. 


SOLDERING.  347 

Iron  presents  rather  more  difficulty,  the  affinity  of  the  tin  being 
less  strong  for  iron  than  for  copper ;  but  the  treatment  is  in  gen- 
eral nearly  the  same.  Old  works  require  that  the  grease  should 
be  removed  with  concentrated  muriatic  acid,  before  the  otlTer  pro- 
cesses are  commenced ;  and  in  cast-iron  vessels  the  grease  often 
penetrates  so  deeply,  owing  fb  the  porous  nature  of  the  metal,  that 
the  re-tinning  is  sometimes  scarcely  possible,  and  it  is  often  more 
economical  to  obtain  a  new  vessel. 

An  alloy  of  nickel,  iron,  and  tin,  has  been  introduced  as  an 
improvement  in  tinning  the  metals.  The  nickel  and  tin  compound 
is  harder  than  tin,  and  endures  a  much  longer  time :  it  is  less  fusi- 
ble, and  will  not  run  or  melt  at  a  heat  that  would  cause  the  ordi- 
nary tinning  of  pans  to  forsake  the  sides  and  lie  in  a  mass  at  the 
bottom.  Also  that  as  an  experiment  to  show  the  tenacity  of  the 
nickel,  a  piece  of  cast-iron  tinned  with  the  compound,  had  been 
subjected  for  a  few  minutes  to  the  white  heat  under  a  blast,  and 
although  the  tin  was  consumed,  the  nickel  remained  as  a  perma- 
nent coating  upon  the  iron. 

The  proportions  of  nickel  and  iron  mixed  with  the  tin  in  order 
to  produce  the  best  tinning,  are  ten  ounces  of  the  best  nickel,  and 
seven  ounces  of  sheet- iron,  to  ten  pounds  of  tin.  These  metals  are 
mixed  in  a  crucible,  and,  to  prevent  the  oxidation  of  the  tin  by 
the  high  temperature  necessary  for  the  fusion  of  the  nickel,  the 
metals  are  covered  with  one  ounce  of  borax  and  three  ounces  of 
pounded  glass.  The  fusion  is  completed  in  about  half  an  hour, 
when  the  composition  is  run  off  through  a  hole  made  in  the  flux. 
In  tinning  metals  with  this  composition  the  workman  proceeds  in 
the  ordinary  manner.  The  process  was  discovered  by  M.  Budie, 
of  the  firm  of  Blaise  and  Co.,  Paris. 

There  is  also  another  method,  that  of  cold-tinning,  by  aid  of  the 
amalgam  of  mercury,  described  at  page  217 ;  but  this  process 
when  applied  to  utensils  employed  for  preparing  or  receiving  food, 
appears  questionable  both  as  regards  effectiveness,  and  wholesome- 
ness,  and  the  activity  of  the  muriatic  acid  must  not  be  forgotten ; 
it  should  be  therefore  washed  carefully  off  with  water.  The  tin 
adheres,  however,  sufficiently  well  to  allow  other  pieces  of  metal 
to  be  afterwards  attached  by  the  ordinary  copper  soldering-bit. 

SOLDERING  PER  SE,  OR  BURNING  TOGETHER. — This  principally 
differs  from  ordinary  soldering,  in  the  circumstances  that  the  unit- 
ing or  intermediate  metal  is  the  same  as  those  to  be  joined,  and 
that  in  general  no  fluxes  are  employed. 

The  method  of  burning  together,  although  it  only  admits  o£ 
limited  application,  is  in  many  cases  of  great  importance,  as  when 
successfully  performed  the  works  assume  the  condition  of  greatest 
strength,  from  all  parts  being  alike.  There  is  no  dissimilarity  be- 
tween the  several  parts  as  when  ordinary  solders  are  used,  which 
are  open  to  an  objection,  that  the  solders  expand  and  contract  by 
heat  either  more  or  less  than  the  metals  to  which  they  are  attached. 
There  is  another  objection  of  far  greater  moment;  the  soldera 


348  THE  PRACTICAL   METAL-WOBKEE's  ASSISTANT. 

oxidize  either  more  or  less  freely  than  the  metals,  and  upon  which 
circumstances  hinge  some  galvanic  or  electrical  phenomena ;  and 
thence  the  soldered  joints  constitute  galvanic  circuits,  which  in 
some  cases  cause  the  more  oxidizable  of  the  two  metals  to  waste 
with  the  greater  rapidity,  especially  when  heat,  moisture,  or  acids 
are  present. 

In  chemical  works  this  is  a  most  serious  inconvenience,  and 
therefore,  leaden  vessels  and  chambers  for  sulphuric  acid  must  not 
be  soldered  with  tin-solder,  the  tin  being  so  much  more  freely  dis- 
solved than  the  lead.  Such  works  were  formerly  burned  together 
by  pouring  red-hot  lead  on  the  joint,  and  fusing  the  parts  into  one 
mass,  by  means  of  a  red-hot  soldering-iron,  as  noticed  at  page  294  ; 
this  is  troublesome  and  tedious,  and  it  is  now  replaced  by  the  auto- 
genous soldering,  to  be  explained. 

Pewter  is  sometimes  burned  together  at  the  external  angles  of 
works,  simply  that  no  difference  of  color  may  exist ;  the  one  edge 
is  allowed  to  stand  a  little  above  the  other,  as  in  Fig.  213,  page 
292,  a  strip  of  the  same  pewter  is  laid  in  the  angle,  and  the  whole 
are  melted  together,  with  a  large  copper-bit,  Fig.  297,  page  342, 
heated  almost  to  redness ;  the  superfluous  metal  is  then  filed  off, 
leaving  a  well-defined  angle  without  any  visible  joint. 

Brass  is  likewise  burned  together  ;  for  instance  the  rims  of  large 
mural  circles  for  observatories,  that  are  five,  six  or  seven  feet 
diameter,  are  sometimes  cast  in  six  or  more  segments,  and  attached 
by  burning.  '  The  ends  of  the  segments  are  filed  clean,  two  pieces 
are  fixed  vertically  in  a  sand  mould  in  their  relative  positions,  a 
shallow  space  is  left  round  the  joint,  and  the  entire  charge  of  a 
crucible,  say  thirty  or  forty  pounds  of  the  melted  brass  a  little 
hotter  than  usual,  is  then  poured  on  the  joint  to  heat  it  to  the 
melting  point.  The  metal  overflows  the  shallow  chamber  or  hole, 
and  runs  into  a  pit  prepared  for  it  in  the  sand ;  but  the  last  quan- 
tity of  metal  that  remains  solidifies  with  the  ends  of  the  segments, 
and  forms  a  joint  almost  or  quite  as  perfect  as  the  general  sub- 
stance of  the  metal ;  the  process  is  repeated  for  every  joint  of  the 
circle. 

The  compensation  balance  of  the  chronometer  and  superior 
watches  is  an  interesting  example  of  natural  soldering.  The 
balance  is  a  small  fly-wheel  made  of  one  piece  of  steel,  covered 
with  a  hoop  of  brass.  The  rim,  consisting  of  the  two  metals,  is 
divided  at  the  two  extremities  of  the  one  diametrical  arm  of  the 
balance,  so  ^that  the  increase  of  temperature  which  weakens  the 
balance-spring  contracts  in  a  proportionate  degree  the  diameter  of 
the  balance,  leaving  the  spring  less  resistance  to  overcome.  This 
occurs  from  the  brass  expanding  much  more  by  heat  than  steel, 
and  it  therefore  curls  the  semicircular  arcs  inwards,  an  action  that 
will  be  immediately  understood  if  we  conceive  the  compound  bar 
of  brass  and  steel  to  be  straight,  as  the  heat  would  render  the 
brass  side  longer  and  convex,  and  in  the  balance  it  renders  it  more 
curved. 


SOLDERING.  349 

In  the  compensation  balance  the  two  metals  are  thus  united  : 
the  disk  of  steel  when  turned  and  pierced  with  a  central  hole,  is 
fixed  by  a  little  screw-bolt  and  nut  at  the  bottom  of  a  small  cruci- 
ble with  a  central  elevation,  smaller  than  the  disk  ;  the  brass  is 
now  melted,  and  the  whole  allowed  to  cool.  The  crucible  is. broken, 
the  excess  of  brass  is  turned  off  in  the  lathe,  the  arms  are  made 
with  the  file  as  usual,  the  rim  is  tapped  to  receive  the  compensa- 
tion .screws  or  weights,  and  lastly  the  hoop  is  divided  in  two 
places,  at  opposite  ends  of  its  diametrical  arm. 

A  little  black  lead  is  generally  introduced  between  the  steel  and 
the  crucible ;  and  other  but  less  exact  modes  of  combining  the 
metals  are  also  employed. 

Cast-iron  is  likewise  united  by  burning,  as  will  be  explained  by 
the  following  example :  To  add  a  flange  to  an  iron  pipe,  a  sand 
mould  is  made  from  a  wood  model  of  the  required  pipe,  but  the 
gusset  or  chamfered  band  between  the  flange  and  tube  is  made 
rather  fuller  than  usual  to  afford  a  little  extra  base  for  the  flange. 
The  mould  is  furnished  with  an  ingate,  entering  exactly  on  the 
horizontal  parting  of  the  mould  at  the  end  of  the  flange,  and  with 
a  waste  head  or  runner  proceeding  upwards  from  the  top  of  the 
flange,  and  leading  over  the  edge  of  the  flask  to  a  hollow  or  pit 
sunk  in  the  sand  of  the  floor. 

The.  end  of  the  pipe  is  filed  quite  clean  at  the  place  of  junction, 
and  a  shallow  nick  is  filed  at  the  inner  edge  to  assist  in  keying  on 
the  flange  ;  lastly,  the  pipe  is  plugged  with  sand  laid  in  the  mould. 
After  the  mould  is  closed,  about  six  or  eight  times  as  much  hot 
metal  as  the  flange  requires  is  poured  through  the  mould.  This 
heats  the  pipe  to  the  temperature  of  the  fluid  iron,  so  that  on  cool- 
ing the  flange  is  attached  sufficiently  firm  to  be,ar  the  ordinary 
pressure  of  screw-bolts,  steam,  etc. 

Steam  and  water-tight  joints,  in  cast-iron  works  not  requiring 
the  power  of  after-separation,  are  often  made  by  means  of  iron 
cement  in  the  following  proportions  :  112  Ibs.  of  cast-iron  filings 
or  borings,  1  Ib.  of  sal-ammoniac,  1  Ib.  of  sulphur,  and  4  Ibs.  of 
whitening.  Small  quantities  of  the  materials  are  mixed  together 
with  a  little  water  shortly  before  use. 

For  minute  cracks  the  cement  is  laid  on  externally  as  a  thin 
seam,  or  for  larger  spaces  it  is  driven  in  with  calking-irons.  The 
edges  of  the  metal  and  the  cement  shortly  commence  one  com- 
mon process  of  rusting,  and  at  the  end  of  a  week  or  ten  days  the 
joints  will  be  found  hard,  dry,  and  permanent. 

The  method  of  burning  is  occasionally  employed  in  most  of  the 
metals  and  alloys  in  making  small  additions  to  old  castings,  and 
also  in  repairing  trifling  holes  and  defects  in  new  ones  ;  it  is  only 
successful,  however,  when  the  pieces  are  filed  quite  clean,  and 
abundance  of  fluid  metal  is  employed,  in  order  to  impart  sufficient 
heat  to  make  a  natural  soldering — a  process  which  is  also,  although 
differently  accomplished,  in  plating  copper  with  silver  (page  198), 
as  the  two  metals  are  raised  to  a  heat  just  short  of  the  melting 


350 


THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 


point  of  the  silver,  and  the  metals  then  unite  without  solder  by 
partial  alloying. 

To  conclude  the  description  of  soldering  processes,  we  have  to 
refer  to  Fig.  300,  which  represents  the  airo-hydrogen  blowpipe  in- 


Fig.  300. 


vented  in  France  by  the  Count  de  Bichemont.  It  is  in  a  great 
measure  converting  the  oxy-hydrogen  blowpipe,  invented  by 
Dr.  Hare,  to  the  service  of  the  workshop,  and  it  is  done  with  great 
simplicity  and  safety.  The  elastic  tube  h  supplies  hydrogen  from 
the  generator,  and  the  pipe  a  supplies  atmospheric  air  from  a  small 
pair  of  double  bellows  6,  worked  by  the  foot  of  the  operator,  and 
3ompressed  by  a  constant  weight  w ;  the  two  pipes  meet  at  the 
arch,  and  proceed  through  the  third  pipe  e  to  the  small  jet  /,  from 
whence  proceeds  the  flame.  All  the  connections  are  by  elastic 
tubes,  which  allow  perfect  freedom  of  motion,  so  that  the  portable 
blowpipe  is  carried  to  the  work. 

In  soldering  by  the  autogenous  process,  the  works  are  first  pre- 
pared and  scraped  clean  as  usual,  the  hydrogen  is  ignited,  and  the 
size  of  the  flame  is  proportioned  by  the  stop-cock  h ;  the  air  is 
then  admitted  through  a,  until  the  flame  assumes  a  fine  pointed 
character,  with  which  the  work  is  united  after  the  general  method 
of  blowpipe  soldering,  except  that  a  strip  of  lead  is  used  instead 
of  solder,  and  generally  without  any  flux. 

This  mode  is  described  as  being  "suitable  to  most  of  the  metals, 
but  its  best  application  appears  to  be  to  plumbers'  work,  and  it  has 
been  adopted  for  such  in  our  government  dock-yards.  The  weight 
of  lead  consumed  in  making  the  joints  is  a  mere  fraction  of  the 
weight  of  ordinary  solder,  which  is  both  more  expensive  and  more 
oxidizable,  from  the  tin  it  contains.  The  gas  soldering,  as  it  is 
called,  removes  likewise  the  risk  of  accidents  from  the  plumbers' 
fires,  as  the  gas  generator,  which  is  in  itself  harmless,  may  be 
allowed  to  remain  on  the  ground  whilst  the  workman  ascends  to 
the  roof,  or  elsewhere,  with  the  pipe. 


SOLDERING.  351 

Lead  is  interposed  as  solder  in  uniting  zinc  to  zinc,  and  it  is  also 
used  in  soldering  the  brass  nozzles  and  cocks  to  the  vessels  of  lead, 
and  those  of  copper  coated  with  lead,  used  as  generators.  Another 

Fig.  301. 


very  practical  application  of  the  gas  flame,  is  for  keeping  the  cop- 
per soldering  tool,  Fig.  301,  at  one  temperature,  which  is  done  by 
leading  the  mixed  gases  through  a  tube  in  the  handle,  so  that  the 
flame  plays  on  the  back  of  the  copper  bit.  This  mode  seems  to  be 
very  well  adapted  to  tin-plate  and  zinc  works,  especially  as  the 
common  street  gas  may  be  used,  thereby  dispensing  with  the  neces- 
sity for  the  gas  generator,  the  construction  and  management  of 
which  alone  remain  to  be  explained. 

The  gas  generator,  Fig.  300,  when  it  is  first  charged,  the  stopper 
1,  is  unscrewed,  and  the  lower  chamber  is  nearly  filled  with  curly 
shreds  of  sheet  zinc,  and  the  stopper  is  replaced.  The  cover  is 
now  removed,  and  a  plug  with  a  long  wire  is  inserted  from  the  top 
into  the  hole  near  3  ;  the  upper  chamber  is  next  filled  with  dilute 
sulphuric  acid  (1  acid  and  6  water),  until  it  is  just  seen  through  the 
central  hole  to  rise  above  the  plate  immediately  beneath  it.  This 
measures  the  quantity  of  liquid  required  to  charge  the  vessel 
without  the  risk  of  overflow.  The  plug  is  now  withdrawn  from 
3,  and  the  cocks  4,  and  h,  being  opened,  the  air  escapes  from  the 
lower  vessel  by  the  pressure  of  the  column  of  water  which  enters 
beneath  the  perforated  bottom  5,  upon  which  the  zinc  rests.  The 
cocks  4  and  h  are  now  closed,  and  by  the  decomposition  of  the 
water  hydrogen  is  generated,  which  occupies  the  upper  part  of  the 
lower  chamber,  and  drives  the  dilute  acid  upwards,  through  the 
aperture  3,  so  as  to  place  matters  in  the  position  of  the  engraving, 
which  represents  the  generator  about  two-thirds  filled  with  gas. 

The  gas  issues  through  the  pipe  h,  when  both  cocks  are  opened, 
but  it  has  to  proceed  through  a  safety  box  6,  in  which  the  syphon 
tube  dips  two  or  three  inches  into  a  little  plain  water  introduced 
at  the  lateral  aperture  7 ;  by  this  precaution  the  contents  of  the 
gasometer  cannot  be  ignited,  as,  should  the  flame  return  through 
the  pipe  h,  it  would  be  intercepted  by  the  water  in  the  safety  box. 
After  three  or  four  days'  constant  work  the  liquid  becomes  con- 
verted into  the  sulphate  of  zinc,  and  is  withdrawn  through  the 
plug  8  ;  the  vessel  is  then  refilled  with  fresh  dilute  acid  as  already 
explained,  but  the  zinc  lasts  a  considerable  time. 

The  generators  are  made  of  lead,  or  where  portability  and  light- 
ness are  required,  of  copper  washed  with  lead,  and  all  the  exposed 
parts  of  the  brass  work  are  washed  and  united  with  lead  to  defend 


352  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

them  from  the  acid.  Occasionally  the  air  is  likewise  supplied  by 
aerometers,  or  vessels  somewhat  resembling  the  gas  generator,  but 
which  are  only  filled  with  common  air,  and  therefore  do  not  require 
the  zinc  or  acid. 

The  following  is  the  broad  difference  between  the  airo-hydrogen 
and  the  oxy -hydrogen  blowpipes.  In  the  oxy-hydrogen  blowpipe, 
the  pure  gases  are  mixed  in  the  exact  proportions  of  two  volumes 
of  hydrogen  to  one  of  oxygen,  which  quantities  when  combined 
constitute  water,  and  in  this  .particular  case  there  is  the  greatest 
condensation  of  volume,  and  the  greatest  evolution  of  latent  as 
well  as  of  sensible  heat.  •  .  9.  •• 

The  airo-hydrogen  blowpipe  is  supplied  with  common  air  and 
with  pure  hydrogen;  this  instrument  is  also  the  most  effective 
when  the  oxygen  and  hydrogen  are  mixed  in  the  proportions  of  1 
to  2 ;  but  the  nitrogen,  which  constitutes  four-fifths  of  our  atmos- 
phere, is  now  in  the  way  and  detracts  from  the  intensity  of  the 
effect. 


CHAPTEE  XX, 

SHEARS. 

CUTTING  NIPPERS  FOR  WIRES. — Shears  are  instruments  of  a 
character  quite  different  from  any  of  those  hitherto  described,  as 
the  cutting  edges  of  shearing  tools  are  always  used  in  pairs,  and 
on  opposite  sides  of  the  material  to  be  sheared  or  severed.  In 
many  cases  the  shears  are  constructed  after  the  manner  of  pincers 
and  pliers,  or  as  two  double-ended  levers  united  at  the  fulcrum  by 
a  pin,  but  other  modes  of  uniting  the  two  cutting  parts  of  the  in- 
struments are  also  employed,  as  will  be  shown. 

The  sections  of  some  varieties  of  this 

Fig-  302-  instrument  are  represented  by  a  b  c  of 

the  annexed  Fig.  302,  from  which  it  will 

be  seen  that  the  edges  of  shears  and 

|      •         g W       scissors  meet  in  lateral  contact,  and  pass 

-\ -  r^J  r^faar"^  ^T^      close  against  one  another,  severing  the 

I       •          |B       *       material  by  two  cuts  or  indentations,  or 

a       ^        c  I  thrusts,  which  take  place  in  the  same 

pa  plane  as  that  in  which  the  blades  are 

situated  and  are  moved. 

Some  of  the  largest  shearing  tools  of  the  kinds  used  by  en- 
gineers, such  as  c,  serve  to  divide  bars  of  iron,  4,  5  or  6  inches 
wide,  and  1  to  2  inches  thick,  then  requiring  the  greatest  possible 
solidity  and  freedom  from  elasticity. 

On  the  other  hand,  some  of  the  finest  scissors  of  the  section  a, 
such  as  are  used  by  ladies  in  cutting  lace,  will  cut  with  the  greatest 


SHEARS.  353 

cleanness  and  perfection  the  most  flexible  thread  or  tissue  of 
threads,  or  the  finest  membranes  met  with  in  animal  or  vegetable 
structures. 

But  this  latter  kind  of  shears,  unlike  the  engineer's  shears,  is 
altogether  useless  unless  possessed  of  a  considerable  share  of  elas- 
ticity, to  keep  their  edges  in  accurate  contact  at  that  point  in  which 
the  blades  at  the  moment  cross  each  other,  as  will  be  explained, 
otherwise  such  thin  materials  are  folded  down  between  the  blades 
instead  of  being  fairly  cut.  The  transition  from  the  elastic  to  the 
inelastic  kinds  of  shears  is  not,  as  may  be  supposed,  by  one 
defined  step,  but  by  gradual  stages,  making  it  as  difficult  iu  this, 
as  in  other  classifications,  to  adopt  any  precise  line  of  demar- 
cation. 

In  addition  to  the  above,  or  to  shears  properly  so  considered, 
there  are  a  few  tools  known  as  cutting  pliers,  or  nippers,  in  which 
the  blades  meet  in  direct  opposition,  but  do  not  pass  each  other  as 
in  the  legitimate  kind  of  shears.  This  kind  is  represented  by  the 
section  d,  Fig.  302. 

Cutting  pliers,  if  they  admit  of  being  classed  with  shears,  are 
certainly  the  most  simple  of  the  group,  and  are  used  for  cutting 
asunder  small  wires,  nails,  and  a  few  other  substances.  Their 
edges  are  simply  opposed  wedges,  exactly  as  shown  in  the  above 
diagram  at  d;  and  as  respects  the  remainder  of  the  instruments 
by  which  their  wedges  are  composed,  the  most  simple  kind  ex- 
actly resembles  carpenters'  ordinary  pincers  for  drawing  out  nails, 
except  that  the  cutting  pincers  are  made  with  thinner  edges  ;  and 
Figs.  303  to  306  represent  different  kinds  of  cutting  pliers  and 
nippers. 

When  cutting  nippers  are  compressed  upon  a  nail  or  a  piece  of 
wire,  they  first  indent  it  on  opposite  sides,  and  when  from  their 
penetration  the  surfaces  of  the  wedges  exert  a  lateral  pressure 
against  the  material,  the  latter  eventually  yields,  and  is  torn  asun- 
der at  the  moment  the  pressure  exerted  by  the  wedges  exceeds  the 
cohesive  strength  of  the  central  metal  yet  uncut.  Consequently 
the  divided  wire  shows  two  beveled  surfaces,  terminating  in  a 
ridge  slightly  torn  and  ragged.  The  quantity  of  the  material 
thus  torn  instead  of  being  cut,  will  be  the  less,  the  softer  the  metal 
and  the  keener  the  pliers ;  but  experience  shows  an  angle  of 
about  30  to  40  degrees  to  be  the  most  economical  for  the  edges  of 
such  tools. 

Little  remains  to  be  said  on  the  varieties  of  cutting  pliers ;  most 
of  these  used  by  general  artisans  and  clockmakers  are  smaller  than 
carpenters'  pincers,  and  the  extremities  of  the  jaws  are  beveled  as 
in  watch-nippers,  Fig.  303,  that  they  may  cut  pins  lying  upon  a  flat 
surface.  Other  cutting  pliers,  called  side-nippers,  are  oblique,  as  in 
Fig.  304.  Those  used  for  the  dressing-case,  and  known  as  nail- 
nippers,  are  concave  on  the  edge,  to  pare  the  nails  convex ;  and 
another  kind,  known  as  nipper-pliers,  bell-hangers'  or  boUkrs1  plit,-*. 
have  flat  points  at  the  end  for  grasping  and  twisting  wirjs,  and 
23  * 


354 


THE   PRACTICAL  METAL-WORKER  S  ASSISTANT. 


cutters  on  the  sides  for  removing  the  waste  ends,  as  shown  in 
Fig.  305. 

The  edges  of  cutting  nippers  are  apt  to  be  notched  if  used  upon 
hard  wires,  or  if  wriggled  whilst  the  cutting  edges  are  buried  in 


Figs.  303 


304 


306. 


the  wire,  and  they  scarcely  admit  of  being  reground  or  repaired. 
This  inconvenience  led  to  a  modification  of  the  instrument,  Fig. 
306,  by  the  enlargement  of  the  extremities,  to  admit  of  loose  cut- 
ters fitted  in  shallow  grooves  being  affixed  by  one  screw  in  each 
as  shown  detached  at  c,  so  that  the  cutters  may  admit  of  removal 
and  restoration  by  grinding,  which  end  is  effectually  obtained, 
although  somewhat  to  the  prejudice  of  the  instrument,  by  increas- 
ing its  bulk. 

SCISSORS  AND  SHEARS  FOR  SOFT  FLEXIBLE  MATERIALS. — The 
nippers  have  edges  of  about  30  to  40  degrees,  meeting  in  direct 
opposition,  but  yet  leave  ragged  edges  on  the  work ;  whereas  the 
shears  have  edges  commonly  of  90  degrees,  seldom  less  than  60 
degrees.  These  edges  pass  each  other  and  leave  the  work  re- 
markably keen  and  exact. 

Let  the  edges  of  scissors  be  ever  so  well  sharpened,  they  act 
very  imperfectly,  if  at  all,  unless  the  blades  are  in  close  contact  at 
the  time  of  passing ;  and  this  imperfection  is  the  more  sensible 
the  thinner  and  more  flexible  the  material  to  be  cut,  as  it  will  then 
fold  down  between  the  blades  if  they  do  not  come  in  contact. 
Whereas,  when  the  blades  exactly  meet,  the  one  serves  to  support 
the  material  whilst  the  other  severs  it ;  or  rather  this  action  is 
reciprocal,  and  each  blade  supports  the  material  for  the  other,  ren- 
dering the  office  of  a  counter-support,  or  of  the  bench,  stool  or 
cutting-board,  used  by  the  carpenter  with  the  paring  chisel. 

On  a  cursory  inspection  of  a  pair  of  ordinary  scissors,  it  may 
be  supposed  that  their  blades  are  made  quite  flat  on  their  faces,  or 
with  truly  plane  surfaces,  like  the  diagram  Fig.  307,  representing 
the  imaginary  longitudinal  section  of  the  instrument,  the  two 
blades  of  which  are  united  by  a  screw,  consisting  of  three  parts 
differing  in  diameter,  namely,  the  head,  the  neck,  and  the  thread  ; 
the  bottom  of  the  countersink  that  receives  the  head  of  the  screw 
k  called  the  shelf  or  the  twitter-bit.  If,  however,  the  insides  of 
scissors  were  made  flat,  and  as  carefully  as  possible,  they  could 
scarcely  be  made  to  cut  slender  fibrous  materials,  or  if  at  all,  then 


SHEARS.  355 

for  only  a  short  period,  and  additional  friction  would  accrue  from 
the  rubbing  of  their  surfaces. 

The  form  which  is  really  adopted,  more  resembles  the  exag- 
gerated diagram  Fig.  308 ;  the  blades  are  each  sloped  some  2  or  3 
degrees  from  the  plane  in  which  they  move,  so  that  their  edges 
alone  come  into  contact ;  instead  of  the  blades  being  straight  in 
their  length  they  are  a  little  curved  so  as  to  overlap ;  and  close 
behizid  the  screw-pin  by  which  they  are  .united,  there  is  a  little 
triangular  elevation,  insignificant  in  size  but  most  important  in 
effect,  which  may  be  considered  as  a  miniature  hillock  or  ridge, 
sloping  away  to  the  general  surface  near  the  hole  for  the  screw. 
This  enlargement  or  bulge  is  technically  called  the  "riding  part" 
and,  as  there  is  one  on  each  blade,  when  the  scissors  are  opened  or 
that  the  blades  are  at  right  angles,  the  points  05  extremities  only 
of  the  riding  parts  come  into  contact,  and  the  joints  may  then 
have  lateral  shake  without  any  prejudice.  But  as  the  blades  are 
closed,  first  the  bases  or  points  of  the  riding  parts,  and  lastly  the 
summits  or  tops,  rub  against  each  other,  and  tilt  the  blades  beyond 
the  central  line  of  the  instrument ;  the  effect  of  which  is  to  keep 
the  successive  portions  of  the  two  edges  in  contact  throughout  the 
length  of  the  cut,  as  by  the  time  the  scissors  are  closed,  the  points 
of  the  blades  are  each  sprung  back  to  the  central  line  of  the  scis- 
sors, which  is  dotted  in  the  diagram. 

Although  scissors  when  in  perfect  condition  for  work  may  be 
loose,  or  shake  on  the  joint  when  fully  opened  (and  thereby  placed 
beyond  their  range  of  action),  they  will  be  always  found  to  be 


309. 


tight  and  free  from  shake,  as  soon  as  the  blades  can  begin  to  cut 
the  material  near  the  joint,  and  so  to  continue  tight  until  they 
meet  at  the  points.  That  all  scissors  do  exhibit  this  construction 
may  be  easily  seen,  as  when  they  are  closed  and  held  edgeways 
between  the  eye  and  the  light,  they  will  be  found  only  to  touch  at 
the  points  and  at  the  riding  parts,  or  those  just  behind  the  joint 
screw,  the  remainder  being  more  or  less  open  and  gently  curved  ; 
and  their  elastic  action  will  also  be  experienced  by  the  touch,  as 
whilst  good  scissors  are  being  closed,  there  is  a  smoothness  of 
contact  which  seems  to  give  evidence  of  some  measure  of  elas- 
ticity. 

Fig.  309  represents  the  section  of  the  one  blade  of  a  pair  of 
scissors,  in  which  the  elastic  principle  is  differently  introduced. 
These  scissors  are  made  without  the  riding  part,  but  instead  thereof, 
immediately  behind  the  screw  which  unites  the  blade  as  usual,  the 


356  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

one  blade  is  perforated,  for  the  purpose  of  admitting  freely  a  small 
pin  or  stud  fixed  to  the  end  of  a  short  and  powerful  spring,  so  that 
the  stud  s,  from  acting  on  the  opposite  blade,  throws  the  points  of 
both  towards  each  other,  so  as  to  give  them  a  tendency  to  cross, 
but  which  being  resisted  by  the  edges  of  the  blades  touching  one 
another,  keeps  them  very  agreeably  in  contact  throughout  their 
motion,  and  causes  them  to  cut  very  well. 

If  further  evidence  is  wanted  of  the  elastic  principle  in  scissors, 
it  is  distinctly  shown  in  sheep  shears,  which  besides  their  ostensi- 
ble purpose  of  shearing  off  the  fleece,  are  used  by  leather  dressers 
and  others.  It  is  well  known  that  sheep  shears,  Fig.  315,  page 
361,  are  made  as  one  piece  of  steel,  which  is  tapered  at  each  end 
to  constitute  the  cutting  edges,  is  then  for  a  distance  fluted  and 
straight  to  form  the  semi-cylindrical  parts  for  the  grasp,  and  that  in 
the  centre  or  opposite  extremity,  the  steel  is  flattened  and  formed  into 
a  bow  by  which  the  blades  are  united  and  kept  distended ;  sheep 
shears  consequently  require  no  joint  pin,  and  the  hands  have  only 
to  compress  them,  as  they  spring  open  for  themselves.  If  sheep 
shears  are  examined  when  fully  opened,  or  when  partially  closed 
by  tying  round  the  blades  a  loop  of  string,  it  will  be  found  that 
the  blades  have  a  tendency  to  spring  into  contact,  as  after  having 
been  pressed  sideways  and  asunder,  the  cutting  edges  immediately 
return  into  exact  contact  the  moment  the  distending  pressure  is 
removed. 

The  construction  of  scissors  with  the  riding-place,  as  adverted 
to  in  Fig.  308,  is  that  which  ordinarily  obtains  in  most  scissors, 
from  the  finest  of  those  used  by  ladies,  to  the  heavy  ponderous 
shears  for  tailors,  which  sometimes  weigh  above  six  pounds,  and 
are  rested  on  the  cutting-board  by  one  of  their  bows,  that  are 
large  enough  to  admit  the  whole  of  the  fingers. 

The  peculiar  form  of  the  insides  of  the  blades  is  in  all  cases  of 
paramount  importance,  and  in  the  manufacture  of  fine  scissors  is 
attended  by  a  person  called  a  "putter-together"  whose  province  it 
is  to  examine  the  screw-joint,  and  see  to  the  form  of  the  riding- 
places,  and  lastly  to  set  the  edges  of  the  scissors,  which  for  gen- 
eral purposes  are  sharpened  on  an  oilstone  at  an  angle  of  about  40 
degrees,  but  for  the  fine  scissors  more  nearly  upright  or  at  30 
degrees  from  the  perpendicular." 

So  important,  indeed,  is  the  configuration  of  the  inner  face  of 
scissors,  that  they  should  never  be  ground  or  meddled  with  at  that 
part,  but  by  a  person  fully  experienced  in  their  action,  and  scissors 
may  with  careful  usage  be  kept  in  order  for  years  without  being 
ground,  if  the  edges  are  occasionally  set  on  the  oilstone  at  the  in- 
clination above  referred  to.  It  will  frequently  happen  that  well- 
made  scissors  which  appear  to  grate  a  little  when  closed,  merely 
do  so  from  dirt  or  dust,  which  if  removed  by  passing  the  finger 
along  the  edges,  will  restore  the  scissors  to  their  smooth  and 
pleasant  action. 

It  seems  quite  uncalled  for  to  enter  into  the  separate  description 


SHEARS.  357 

of  various  instruments  known  as  button-hole  scissors,  cutting-out, 
drapers',  flower,  garden,  and  grape  scissors,  horse  trimming  scis- 
sors ;  hair,  lace,  lamp,  nail,  paper,  pocket,  stationers',  and  tailors' 
scissors,  and  many  others ;  nor  of  the  large  shears  for  the  garden, 
such  as  pruning,  trimming,  and  border  shears,  the  distinctions  be- 
tween which  varieties  are  sufficiently  known  to  those  who  use  the 
several  kinds,  but  the  author  will  merely  notice  such  of  them  as 
present  any  peculiarity  of  structure. 

Button-hole,  scissors  are  notched  out  towards  the  joint  screw  as 
in  Fig.  311,  so  as  to  enable  the  instrument  to  make  the  incision  a 

Figs.  310  311. 


Fig.  312. 

little  distant  from  the  edge  of  the  material ;  the  joint  must  be  made 
stiffj  so  as  to  prevent  the  points  catching  against  each  other. 

Flower  and  grape  scissors  assume  the  section  of  Fig.  310,  so  that 
they  first  cut  the  stem,  and  then  hold  it  like  a  pair  of  pliers ;  the 
one  blade  requires  to  be  made  in  two  parts  riveted  together ;  when 
entirely -closed  they  present  an  elliptical  section  a ;  and  b  shows 
how  the  stem  of  the  flower  is  grasped ;  the  blades  are  rounded  at 
all  parts  that  they  may  not  injure  the  plants. 

Lamp  scissors  have  the  one  blade  very  broad,  and  with  a  little 
rim,  to  prevent  the  snuff  of  the  lamp  falling  on  the  carpet. 

Nail  scissors  for  the  dressing-case  are  made  very  strong,  and 
with  short  blades.  In  using  scissors  formed  in  the  ordinary  mode, 
the  fingers  and  thumb  of  the  right  hand  have  naturally  a  tendency 
to  press  the  blades  together,  in  that  position  in  which  they  are  in- 
tended to  cut ;  but  the  left  hand,  on  the  contrary,  has  a  tendency 
to  separate  the  blades  and  defeat  the  principle  on  which  scissors 
act.  Therefore  nail  scissors  are  made  in  pairs,  and  formed  in 
opposite  ways,  or  as  "  rights  and  lefts,"  so  that  they  may  suit  the 
respective  hands. 

Pocket  scissors  have  blades  which  admit  of  being  locked  to- 
gether in  the  form  represented  in  Fig.  312,  as  the  point  of  one  blade 
catches  into  a  small  spring  near  the  bow  of  the  other ;  and  the  in- 
strument cannot  be  opened  until  the  spring  or  catch  is  released 
with  the  nail.  When  closed  for  the  pocket,  the  bows  stand  on  one 
line  as  at  a  b,  when  opened  for  use  as  at  a  c. 

Surgical  scissors  are  of  many  forms,  but  have  generally  short 
blades,  and  long,  straight,  slender  handles,  that  the  hand  may  not 


358  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

impede  the  vision.  In  some  of  the  surgical  scissors  the  blades  are 
curved  as  scimitars,  and  others  are  curved  sideways ;  these  kinds 
are  difficult  to  make,  as  the  elasticity  of  contact  in  the  blade  is  re- 
quired nevertheless  to  be  maintained. 

Many  of  the  shears  and  scissors  used  in  gardening,  only  differ 
from  scissors  and  shears  in  general  in  their  size,  and  the  adaptation 
of  their  handles,  some  of  which  are  of  wood,  and  placed  at  an 
angle  of  40  or  50  degrees,  as  in  the  letter  Y  inverted.  Other 
garden  shears  used  in  trimming  borders,  have  handles  a  yard  long 
and  inclined  about  80  degrees  to  the  blades,  which  may  therefore 
lie  on  the  ground  whilst  the  individual  stands  nearly  ferect.  Some 
of  the  border  shears  have  rollers  to  facilitate  their  movement  along 
the  ground. 

In  pruning  shears  and  scissors,  two  peculiarities  of  form  are 
judiciously  introduced.  In  the  more  simple  of  the  two  kinds, 
which  is  shown  in  Fig.  313,  the  one  part  of  the  instrument  termi- 
nates in  a  hook,  with  a  broad  and  sometimes  a  roughened  edge,  to 
retain  the  branch  from  slipping  away ;  the  other  part  of  the  in- 
strument is  formed  as  a  thin  cutting  blade,  the  edge  of  which  is 
convex.  Theoretically  it  should  be  part  of  a  logarithmic  spiral, 
in  which  case  the  edge  of  the  cutter  would  present  a  constant  angle 
to  the  work  throughout  its  action,  and  slide  laterally  through  the 
incision  made  by  itself,  or  make  a  sliding  cut ;  whereas  if  the  edge 
of  the  blade  were  radial,  it  would  make  a  direct  cut  without  any 
sliding,  as  in  a  paring  chisel.  The  spiral  blade  cuts  more  easily, 
and  will  therefore  remove  a  larger  branch,  with  an  action  precisely 
analogous  to  that  of  the  oblique  cutters  in  some  of  the  planes, 
although  differently  produced. 

Some  of  these  instruments,  when  a  little  modified  in  form,  are 
mounted  on  poles  from  6  to  10  feet  long,  and  are  actuated  by  a 
catgut;  this  tool,  which  is  known  as  the  Averuncator,  is  very 
efficient  for  pruning  at  a  considerable  distance  above  the  head. 

The  other  pruning  shears  represented  in  Fig.  314,  are  denom- 


Figs.  313  b        a  314. 


inated  sliding  shears ;  the  pin  that  unites  the  two  parts  fits  in  a 
round  hole  in  the  one  blade  and  a  long  mortise  in  the  other,  and  a 
link  or  bridle-rod  c  e,  is  attached  by  a  screw  to  each  lever ;  in  con- 
sequence, when  the  instrument  is  fully  opened  the  pin  or  fulcrum 
is  at  the  end  a,  of  the  mortise,  whereas,  on  the  shears  being  grad- 
ually closed,  the  cutting  blade  slides  downwards  upon  the  pin  until 
the  fulcrum  is  near  the  opposite  end  b.  In  this  modification  of 


SHEARS.  359 

shears  the  sliding  action  is  produced  to  a  much  greater  extent 
than  with  the  spiral  blade,  but  the  construction  is  a  little  more  ex- 
pensive ;  and  as  the  instrument  is  not  provided  with  bows  for  the 
fingers,  the  spring  d  e,  is  added  to  throw  it  open. 

Before  dismissing  this  subject,  two  modifications  of  shears  will 
be  briefly  adverted  to ;  those  used  by  card  makers,  and  the  revolving 
shears  employed  in  manufacturing  woollen  cloth. 

pard  paper  is  prepared  in  large  sheets ;  when  dried  and  pressed 
it  is  cut  into  square  pieces  of  the  required  sizes  by  means  of  long 
shears,  the  one  blade  of  which  is  fixed  at  the  end  of  a  table,  and 
has  the  joint  at  the  farther  extremity,  whilst  the  cutting  blade  has 
a  handle  in  front,  and  moves  through  a  loop  to  keep  the  blade  in  its 
position,  as  in  some  chaff-cutting  machines ;  there  is  also  a  stop 
fixed  parallel  with  the  blades,  and  as  distant  as  the  width  of  the 
slips  into  which  the  card  is  first  divided,  and  these  slips  are  then 
cut  again  the  length  way  of  the  cards. .  The  shears  are  moved  so 
rapidly,  that  the  action  sounds  like  that  of  knocking  at  a  door,  and 
still  the  cards  agree  most  rigidly  in  size. 

Eevolving  shears  or  "perpetual  shears"  are  used  for  shearing  off 
the  loose  fibres  from  the  face  of  woollen  cloths.  For  narrow  cloths 
the  cylinders  are  30  inches  long  and  2  in  diameter,  eight  thin  knives 
are  twisted  around  the  cylinders,  making  2  J  turns  of  a  coarse  screw, 
and  are  secured  by  screws  and  nuts  which  pass  through  flanges  at 
the  ends  of  the  axis :  formerly  the  cylinders  were  grooved  and  fitted 
with  several  thin  narrow  plates  of  steel  6  or  8  inches  long.  The 
edges  of  the  eight  blades  are  ground  so  as  to  constitute  parts  of  a 
cylinder,  by  a  grinder  or  strickle  fed  with  emery,  passed  to  and -fro 
on  a  slide  parallel  with  the  axis  of  the  cylinder,  which  is  driven  at 
about  1200  turns  in  the  minute. 

In  use,  the  cylinder  revolves  about  as  quickly,  and  in  contact 
with  the  edge  of  a  long  thin  plate  of  steel,  called  the  ledger-Hade, 
which  has  a  very  keen  rectilinear  edge,  measuring  40  to  50  degrees ; 
the  blade  is  fixed  as  a  tangent  to  the  cylinder,  and  the  two  are 
mounted  on  a  swing  carriage  with  two  handles,  so  as  to  be  brought 
down  by  the  hands  to  a  fixed  stop.  The  edge  of  the  ledger-blade 
is  sharpened,  by  grinding  it  against  the  cylinder  itself  with  flour 
emery  and  oil,  by  which  the  two  are  sure  to  agree  throughout  their 
length. 

The  cloth,  before  it  goes  through  the  process  of  cutting,  is 
brushed  so  as  to  raise  the  fibres,  it  then  passes  from  a  roller  over  a 
round  bar,  and  comes  in  contact  with  the  spring  bed,  which  is  a 
long  elastic  plate  of  steel,  fixed  to  the  framing  of  the  machine,  and 
nearly  as  a  tangent  to  the  cylinder ;  this  brings  the  fibres  of  the 
cloth  within  the  range  of  the  cutting  edges,  which  reduce  them 
very  exactly  to  one  level.  The  machine  has  several  adjustments 
ior  determining,  with  great  nicety,  the  relative  positions  of  the 
cylinder,  ledger-blade  and  spring  bar,  but  which  could  not  be  con- 
veyed withput  elaborate  drawings.  Formerly  the  cloth  was  passed 
over  a  fixed  bed  having  a  nearly  sharp  angular  ridge,  but  which 


360  THE    PRACTICAL    METAL-WORKERS   ASSISTANT. 

mode  was  far  more  liable  to  cut  holes  in  tlie  cloth  than  the  spring 
bed. 

Broadcloths  require  cylinders  65  inches  long,  and  machinery  of 
proportionally  greater  strength.  In  the  cross-cutting  machine,  the 
cloth  is  cut  from  list  to  list,  or  transversely,  in  which  case  the  cloth 
is  stretched  by  hooks  at  the  two  edges,  and  there  are  two  spring 
beds ;  the  cylinder  in  this  machine  is  40  inches  long,  and  the  cloth 
is  shifted  that  quantity  between  every  trip  until  the  whole  piece  is 
sheared.  The  perpetual  shears  are  also  successfully  applied  to 
coarse  fabrics,  including  carpets. 

A  modification  of  the  above  revolving  shears,  made  in  a  much 
less  exact  manner  for  mowing  grass  lawns,  is  fitted  up  somewhat 
as  a  wheelbarrow,  or  hand  truck,  so  that  the  rotation  of  the  wheels 
upon  which  the  machine  is  rolled  along,  gives  motion  to  the  shears, 
which  crop  the  grass  to  a  level  surface. 

SHEARS  FOR  METAL  WORKED  BY  MANUAL  POWER. — When 
metals  are  very  thin,  such  as  the  latten  brass  used  for  plating,  and 
Other  purposes,  they  may  be  readily  cut  with  stout  scissors ;  and 
accordingly,  we  find  the  weakest  of  the  shears  for  metal  are  merely 
some  few  removes  in  strength  beyond  the  strong  scissors  for  softer 
substances. 

It  is  however  to  be  observed  that,  as  common  scissors  are  sharp- 
ened to  an  angle  varying  from  about  50  to  60  degrees,  they  may 
fairly  be  considered  to  cut  the  materials  submitted  to  their  action ; 
but  shears  for  metal  have  in  general  rectangular  edges,  as  they  are 
seldom  more  acute  than  80  degrees,  and  therefore  instead  of  cutting 
into  the  material,  they  rather  force  the  two  parts  asunder,  by  the 
pressure  of  the  two  blades  being  exerted  on  opposite  sides  of  the 
line  of  division. 

It  was  recently  stated  to  be  of  the  utmost  importance,  that  the 
blades  of  the  weaker  or  elastic  kind  of  shears  should  be  absolutely 
in  contact,  or  else  thin  flexible  materials  would  be  folded  down 
between  their  blades  without  being  cut. 

And  it  may  now  be  urged  as  of  equal  importance,  that  the  blades 
of  the  shears  for  metal  should  be  also  exactly  in  contact,  not  that 
rigid  plates  or  bars  of  metal  could  be  bent  or  folded  down  between 
their  blades,  even  if  these  were  a  little  distant ;  but  the  resistance 
to  the  operation  of  cutting  would  be  then  enormously  increased, 
because  the  force  exerted  to  compress  the  shears  would  not  be  then 
exerted  in  the  line  of  their  greatest  resistance,  which  is  strictly  the 
case  when  the  edges  truly  meet  in  one  plane. 

If  the  blades  were  distant  as  in  Fig.  320,  from  the  want  of  direct 
support,  the  bar  or  plate  would  be  tilted  up  and  become  jammed ; 
this  would  tend  further  to  separate  the  blades,  and  the  shears  would 
be  strained  or  perhaps  broken  without  dividing  the  bar,  whereas 
all  these  evils  are  avoided  if  the  shears  close  accurately  in  one  and 
the  same  plane,  as  if  the  lower  blade  were  shifted  to  the  dotted  line, 
and  in  which  case  they  require  the  least  expenditure  of  power  and 
act  with  the  best  effect. 


SHEARS. 


361 


Hand  shears,  which  are  the  smallest  of  these  tools,  are  made  of 
the  form  represented  in  Fig.  316,  and  vary  from  about  four  to  nine 


319 


318 


320. 


inches  in  total  length.  They  are  much  used  by  tinmen,  copper- 
smiths, silversmiths  and  others  who  work  in  sheet  metals,  and  are 
often  called  snips,  to  distinguish  them  from  bench  shears.  Some- 
times, however,  they  are  fixed  by  the  one  limb  in  the  table  or  tail 
vice,  and  then  become  essentially  bench  shears, — and  this  enables 
them  to  be  used  with  somewhat  increased  power. 

Bench  shears  of  the  ordinary  form  are  represented  in  Fig.  317. 
The  square  tang  t  is  inserted  in  a  hole  in  the  bench,  or  in  a  large 
block  of  wood,  or  else  in  the  chaps  of  the  bench  vice  itself.  A 
less  usual  modification  is  seen  in  Fig.  318,  with  the  joint  at  the  far 
end,  and  the  cutting  part  between  the  joint  and  the  handle. 

Bench  shears  vary  in  total  length  from  about  one  foot  and  a  half 
to  four  feet,  and  the  blades  occupy  about  one-fifth  of  the  length. 
Sometimes  to  increase  the  power  of  these  shears  the  handle  is 
forged  thicker  at  the  end  to  add  weight,  so  that  when  the  instru- 
ment is  closed  with  a  jerk,  it  may  by  its  momentum  cut  thicker 
metal  than  could  be  acted  upon  by  a  simple  thrust ;  but  when  con- 
siderable power  is  required  it  is  better  to  resort  to  the  shears  next 
described. 

Purchase  shears,  which  are  represented  in  Fig.  321,  are  in  every 
respect  more  powerful  than  those  previously  noticed  ;  the  framing 
is  much  more  massive,  and  the  cutters  are  rectangular  bars  of 
steel  inserted  in  grooves,  to  admit  of  their  being  readily  sharp- 
ened or  renewed.  Instead  of  the  hand  being  applied  on  the  first 
lever  or  a  b,  a  second  lever  c  d  e  is  added,  and  united  to  the  first 
by  the  link  6  d,  and  but  for  tfee  limit  of  the  paper  the  hand  lever 
c  d  e  would  have  been  represented  of  twice  its  present  length. 

As  the  length  of  the  part  a  b  is  three  to  four  times  the  length  of 
c  d,  the  hand  has  to  move  through  three  to  four  times  the  space  it 
would  if  applied  directly  to  the  shear  lever,  and  consequently  the 
purchase  shears  have  three  to  four  times  the  force  of  common 
shears,  supposing  the  manual  lever  to  be  of  equal  length  in  each 


362 


THE   PEACTICAL    METAL-WOKKER's   ASSISTANT. 


kind.  There  is  usually  at  the  back  of  the  moving  blade  a  very 
powerful  spring  or  back  stay,  to  keep  the  two  edges  in  contact,  and 
still  further  behind  a  stop  to  determine  the  lengths  or  widths  of 
the  pieces  sheared  off. 


Fig.  321. 


Before  using  the  shears,  in  those  cases  where  the  stop  is  not  em- 
ployed to  determine  the  width,  it  is  usual  to  mark  on  the  work  the 
lines  upon  which  it  is  intended  to  be  sheared.  The  shears  are  then 
opened  to  the  full,  and  the  extremity  of  the  line  is  placed  in  the 
angle  formed  by  the  jaws.  Tf  the  work  is  short,  it  is  also  observed 
whether  the  opposite  end  of  the  line  lies  exactly  on  the  edge  of 
the  lower  blade ;  but  if  the  work  is  long,  the  guidance  is  n 


When  the  blades  are  closed  the  work  will  probably  slip  endlong, 
notwithstanding  the  resistance  of  the  hand,  until  the  angle  at  which 
the  blades  meet  is  so  far  reduced  that  they  begin  to  grasp  the  work, 
when  the  extreme  edge  will  be  first  cut  through,  and  then  the 
incision  will  be  extended  to  the  full  length  of  the  blades. 

As,  however,  each  successive  portion  is  severed,  the  two  parts 
are  bent  asunder  to  the  angle  formed  by  the  blades,  and  both  pieces 
become  somewhat  curved  or  curled  up.  Provided  the  cut  is 
through  the  middle  of  the  sheet,  so  that  both  are  equally  strong, 
the  two  parts  become  curved  in  the  same  degree ;  but  when  a  nar- 
row and  consequently  weaker  piece  is  removed  from  the  edge  of 
a  wide  sheet,  the  curling-up  occurs  almost  exclusively  in  the  .nar- 
row strip,  on  account  of  its  feebleness.  In  long  pieces  it  is  some- 
times necessary  to  increase  the  curvature,  in  order  that  as  the  work 
is  sheared  off  the  one  part  may  pass  above,  and  the  other  below 
the  rivet  or  screw  by  which  the  halves  of  the  shears  are  united. 

When  from  use  or  accident  the  joint  becomes  loose,  so  as  not  to 
retain  the  two  parts  in  contact,  in  order  to  make  the  shears  cut, 
the  moving  half  must  be  pressed  against  that  which  is  fixed  to  the 
pedestal  or  tail  vice.  Sometimes  the  sway  of  the  blades  of.  jointed 


SHEARS.  363 

shears  is  prevented  by  allowing  the  moving  arm  to  pass  through  a 
loop  or  guide  which  may  retain  it  in  position. 

Such  a  guide  is  mostly  used  in  the  light  shears  with  which  prin- 
ters cut  their  space  line  leads,  or  those  thin  strips  of  metal  inserted 
between  the  lines  of  type,  to  separate  them  and  make  the  printing 
more  open.  The  leads  are  cast  in  strips  about  a  foot  long,  and  are 
cut  into  pieces  of  the  exact  width  of  a  page,  by  laying  them  in  a 
trough  having  at  the  end  a  pair  of  shears,  and  beyond  these  a  stop 
to  determine  the  precise  length,  so  that  any  number  of  the  leads 
may  be  cut  exactly  to  the  length  required.  Before  adverting  to 
the  powerful  shears  used  by  engineers,  two  modifications  of  those 
already  described  will  be  noticed. 

Fig.  319,  page  361,  represents  the  section  through  the  blades  of 
a  pair  of  shears,  by  which  the  tags  or  tin  ferrules  at  the  end  of 
silk  laces  are  cut  and  bent  at  one  process,  the  general  aspect  of  the 
tool  being  that  of  Fig.  317,  page  361.  The  shearing  blades  are 
shaded  obliquely  in  Fig.  319,  and  to  the  lower,  which  is  fluted  on 
the  edge,  is  attached  a  stop  that  determines  the  width  of  the  piece 
removed  from  the  strip  s,  to  make  the  tag.  The  upper  shear  blade, 
which  is  ground  more  acutely  than  usual,  carries  a  ridge  piece 
(shaded  vertically),  which  compresses  the  strip  as  it  is  cut  off,  into 
the  fluted  edge  of  the  lower  blade,  and  thereby  throws  it  into  a  chan- 
neled form ;  and  by  the  employment  of  a  pair  of  hollow  pliers,  or 
else  a  light  hammer  and  a  hollow  crease,  the  bending  is  readily 
completed,  and  the  tag  attached  to  the  cord. 

A  nearly  similar  machine,  but  constructed  more  in  accordance 
with  the  printers'  space  line  shears,  is  used  for  cutting  slips  of  thin 
latten  brass,  into  the  channeled  pens  used  in  stationers'  machines 
for  ruling  the  blue  and  red  lines  on  paper  for  account  books,  etc. 
The  one  side  of  a  slip  of  brass  1£  inch  wide,  is  thus  cut  and  chan- 
neled at  intervals  suited  to  every  line ;  the  sides  of  every  channel 
are  closed  to  form  a  .narrow  groove,  and  the  intervening  pieces  are 
removed  with  hand  shears.  The  compound  pen  is  fixed  on  a  hinged 
board,  and  a  strip  of  thick  flannel  laid  at  the  top  of  the  pen,  is 
saturated  with  ink  which  flows  steadily  down  all  the  channels, 
whilst  the  paper  is  moved  horizontally  under  the  pens,  by  two  or 
three  rollers  and  tapes,  somewhat  as  in  the  feeding  apparatus*  of 
printing  machines,  and  thus  the  whole  page  is  ruled  one  way  and 
very  quickly. 

Shears  of  the  above  kinds,  with  rectilinear  blades,  are  not  suited 
to  cutting  out  curvilinear  objects,  such  for  example  as  the  sides  of 
callipers  a,  Fig.  349.  The  outline  of  such  callipers  is  first  of  all 
marked  on  the  sheet  of  steel  from  a  templet,  and  with  a  brass  wire 
which  leaves  a  sufficient  trace ;  the  outline  is  followed  with  a  ham- 
mer and  chisel  upon  an  anvil,  the  chisel  having  a  rounded  or  con- 
vex edge.  Detached  cuts  running  into  one  another  are  made 
round  the  curve,  and  the  work  is  finally  separated  by  pinching  it 
in  the  tail-vice  successively  at  all  parts  of  the  curve,  and  wrig- 
gling the  other  edge  of  the  sheet  with  the  hand  until  it  breaks. 


364 


THE   PRACTICAL    METAL; WORKER  S   ASSISTANT. 


The  vice  is  often  also  used  for  cutting  off  straight  pieces,  which 
are  then  fixed  with  the  line  of  division  exactly  flush  with  the 
chaps,  and  an  ordinary  straight  chisel  is  so  applied,  that  the  cham- 
fer of  the  tool  rests  on  the  chaps  of  the  vice,  and  the  edge  lies  at 
a  small  angle  to  the  work,  and  after  each  successive  blow,  the 
chisel  is  moved  a  little  to  the  left  without  losing  its  general 
position. 

ENGINEERS'  SHEARING  TOOLS  ;  GENERALLY  WORKED  BY  STEAM 
POWER. — The  earliest  machines  of  this  class  were  scarcely  more 
than  a  magnified  copy  of  the  bench  shears  shown  on  page  361, 
but  made  very  much  stronger ;  thus,  Fig.  322  represents  a  shear- 
ing and  squeezing  tool  used  in  some  iron  works  and  smithies.  It 
has  one  massive  piece  that  is  fixed  to  the  ground,  and  jointed  to 
it  is  the  lever,  which  carries  at  a,  a  pair  of  shearing  cutters  situated 
exactly  on  two  radii  struck  from  the  centre  of  motion  ;  this 


Figs.  322 


machine  has  also  two  squeezers  b,  for  moulding  pieces  of  iron 
when  red-hot  to  the  particular  forms  of  the  dies.  The  longer  end 
of  the  lever  is  united  by  a  connecting-rod  to  an  eccentric  stud  in 
the  disk  d,  which  is  made  to  revolve  by  the  steam-engine. 

Shears  are  sometimes  moved  by  means  of  an  axis  carrying  two 
rollers,  placed  at  the  extremities  of  a  diametrical  arm,  as  in  Fig. 
323.  The  one  roller  acts  on  the  radial  part  of  the  shear  lever  in 
the  act  of  cutting,  and  the  curved  part  then  allows  the  lever  to 
descend  by  its  own  weight  rapidly,  yet  without  a  jerk,  by  the  time 
the  other  roller  comes  into  action  for  the  succeeding  stroke  of  the 
machine,  which  by  this  double  eccentric  makes  two  reciprocations 
for  every  revolution  of  the  shaft. 

It  ^is,  however,  more  usual  to  employ  cams,  as  in  Fig.  324,  and 
in  this  case  the  part  of  the  cam  which  lifts  the  shear  lever  is  usu- 
ally spiral,  so  as  to  raise  it  with  equal  velocity ;  the  curve  of  the 
back  is  immaterial,  provided  it  forms  a  continuous  line  so  as  to 
prevent  the  lever  descending  with  a  jerk. 

Fig.  325  represents  the  double  shears ;  the  one  part,  shown  also 
detached,  presents  two  horizontal  but  discontinuous  edges  with 
the  axis  in  the  centre,  this  piece  is  fixed  to  a  firm  support ;  the 
other  or  the  moving  part  somewhat  resembles  the  letter  T  or  a 
pendulum,  to  the  lower  end  of  which,  and  beneath  the  floor,  is 


SHEARS. 


365 


jointed  a  connecting-rod,  that  unites  the  pendulum  with  an  ccc ci- 
tric or  crank  driven  by  the  engine.  The  machine  is  double,  or 
cuts  on  either  side,  and  has  two  pairs  of  rectangular  cutters  of 
hardened  steel,  which  may  be  shifted  to  bring  the  four  edges  of 
all  of  them  successively  into  action. 

Boiler  makers  have  great  use  for  powerful  shears  for  cutting 
plate  iron  from  £  to  £,  and  sometimes  f  inch  thick ;  and  the  next 
stage  of  their  work  is  to  punch  the  rivet  holes  by  which  the  plates 
are  attached.  The  two  processes  of  shearing  and  punching  are  so 
far  analogous  in  their  requirements,  that  it  is  usual  to  unite  the 
two  processes  in  one  machine ;  and  as  it  sometimes  happens  the 


326. 


boiler  maker's  yard  is  at  a  distance  from  the  general  factory,  it 
then  becomes  necessary  to  work  the  shears  by  hand  with  a  winch 
handle,  and  which  is  effected  in  the  manner  shown  in  Fig.  326,  by 
the  introduction  of  only  one  wheel  and  pinion.  The  wheel  is  fixed 
on  the  cam  shaft,  the  pinion  on  the  same  axis  that  carries  the 
heavy  fly-wheel  employed  to  give  the  required  momentum ;  this 
mode  of  working  the  shearing  and  punching  engine  is  perfectly 
successful,  but  of  course  less  economical  than  steam  or  water  power, 
the  agency  of  which  the  machine  is  also  adapted  to  receive. 

When  shears  that  move  on  a  joint  and  have  radial  cutters  as  in 
Fig.  322,  are  employed  for  thick  bars,  owing  to  the  distance  to 
which  their  jaws  are  opened,  they  meet  at  a  considerable  angle, 
and  therefore  from  their  obliquity  they  do  not  grasp  the  thick  bar. 
but  allow  it  to  slide  gradually  from  between  them,  to  prevent  which 
a  rigid  stop  is  added  at  the  part  c,  Fig.  322,  when,  as  the  bar  can 
no  longer  slide  away  it  becomes  severed.  The  shears  with  radial 
cutters,  are  also  liable  from  their  very  oblique  action  to  curve  the 
plates ;  neither  do  they  serve  for  making  long  cuts,  as  the  joint 
then  prevents  the  free  passage  of  long  work. 

All  these  inconveniences,  however,  are  obviated  in  the  shearing 


366 


THE   PKACTICAL   METAL-WORKER'S   ASSISTANT. 


machines  with  slides,  in  which  the  edges  ^approach  in  a  right  line 
instead  of  radially,  and  are  also  nearly  obviated  in  the  very  massive 
and  powerful  shearing  and  punching  tool  with  jointed  lever,  first 
employed  by  French  engineers  and  represented  in  Fig.  326,  which 
occupies  an  entire  length  of  eleven  feet,  and  serves  for  cutting  plates 
not  exceeding  f  inch  thick,  cutting  12  inches  in  length  at  a  time, 
and  punching  holes  of  1  £  inch  diameter  in  f  inch  iron.  The  shear- 
ing cutters  are  in  this  machine  15  inches  long  and  raised  above  the 
centre  of  motion ;  as  they  lie  on  a  chord  instead  of  a  radius,  the 
longest  pieces  may  therefore  be  cut  without  interference  from  the 
joint,  and  the  cutters  have  the  further  advantage  of  meeting  at  a 
much  smaller  angle  than  if  fitted  radially. 

The  portable  punching  and  shearing  machine  shown  in  front  and 
side  elevation  in  Figs.  327  and  328,  will  serve  for  a  general  exam- 
ple of  such  machines,  as  the  differences  in  the  several  constructions 
are  only  those  of  form  and  arrangement,  and  not  of  principle. 


Figs.  327 


328. 


This  machine  stands  upon  a  base  of  a  triangular  form,  and  has 
in  front  a  strong  chamfer  slide,  which  is  reciprocated  in  a  vertical 
line,  by  an  eccentric  that  is  concealed  from  view,  it  being  immedi- 
ately behind  the  slide,  and  upon  the  same  axis,  as  the  eccentric  is 
the  toothed  wheel.  The  pinion  that  takes  into  this  wheel,  is  on 
the  shaft  that  carries  the  fly  wheel,  and  one  of  the  arms  of  the  latter 
receives  the  handle  by  which  the  machine  is  usually  worked ;  or 
if  it  is  driven  by  power,  fast  and  loose  pulleys  are  then  fixed  on 
the  same  axis  as  the  fly  wheel. 

The  upper  part  of  the  slide  carries  a  shearing  cutter,  which  is 


SHEARS.  367 

about  7  inches  wide,  and  meets  a  similar  cutter  that  is  fixed  to  the 
upper  and  overhanging  part  of  the  casting.  The  cutters,  although 
ground  with  nearly  rectangular  edges,  are  beveled  to  the  extent  of 
about  three-fourths  of  an  inch  in  the  direction  of  their  length,  that 
they  may  commence  their  work  on  the  one  edge,  and  therefore 
more  gradually  than  if  the  entire  width  of  the  cutter  penetrated  at 
the  same  instant :  this  degree  of  obliquity  does  not  cause  the  work 
to  slide  from  the  shears,  neither  does  it  materially  curl  up  the 
work ;  and  as  the  blades  are  quite  clear  of  the  framing,  a  cut  may 
be  extended  throughout  the  longest  works,  provided  the  cut  is  not 
more  than  five  inches  from  the  edge  of  the  plate,  the  distance  of 
the  cutters  from  the  framing  of  the  machine. 

The  above  machine,  which  measures  in  total  height  about  five 
feet,  makes  12  or  15  strokes  per  minute,  shears  £  inch  iron  plates, 
and  punches  f  holes  in  iron  £  inch  thick.  A  larger  machine 
makes  10  or  12  strokes  per  minute,  shears  f  inch  plate,  and  punches 
1J  inch  holes  in  iron  f  inch  thick;  and  a  still  heavier  machine, 
working  at  8  or  10  strokes  in  the  minute,  shears  1  inch  plates,  and 
punches  2  inch  holes  in  iron  1  inch  thick.  Some  of  these  are  pro- 
vided with  railways  by  which  the  work  is  carried  to  the  shears  or 
punches,  as  will  be  described;  and  the  bar-cutting  machine,  having 
only  shearing  cutters  at  the  bottom,  and  the  eccentric  at  the  top  of 
the  slide,  is  used  for  cutting  bars  not  exceeding  6f  inches  wide  by 
If  thick,  or  bars  2  or  2£  square,  but  we  think  these  dimensions 
of  the  works  performed  might,  if  required,  be  greatly  exceeded  in 
heavier  machines. 

There  is  a  shearing  machine  for  'cutting  wide  plates  of  sheet  iron, 
which  is  used  in  the  manufacture  of  wrought  iron ;  it  has  two  wide 
cutters  of  steel  fixed  to  the  edges  of  thick  plates  of  cast-iron ;  the 
lower  cutter  is  at  rest  and  quite  horizontal,  the  upper  cutter  bar  is 
fitted  in  grooves  at  the  end  of  the  frame,  so  as  to  be  carried  up  and 
down  vertically,  by  a  shaft  or  spindle  immediately  above  the  cut- 
ter and  parallel  with  it ;  this  shaft  has  an  eccentric  at  each  end, 
and  one  in  the  centre,  and  three  connecting  links,  which  attach  the 
cutter  frame  to  the  eccentrics,  and  give  it  a  small  reciprocating  mo- 
tion. The  upper  cutter  is  a  little  oblique,  so  as  to  begin  to  act  at 
the  one  end,  and  in  removing  the  strips  curls  them  but  very  little. 

A  vice  for  cutting  wide  pieces  of  boiler  plate,  is  based  on  the 
mode  of  cutting  thin  slips  of  sheet  metal  over  the  chaps  of  the 
ordinary  tail  vice,  as  described  on  page  363-4.  The  jaws  of  the 
machine  are  about  six  feet  long,  faced  with  steel,  and  powerfully 
closed  by  two  perpendicular  screws  and  nuts,  one  at  each  end, 
which  also  secure  the  machine  to  the  ground. 

The  plate  of  iron  is  therefore  fixed  horizontally  and  with  the 
line  of  division  level  with  the  jaws.  A  strong  rod  chisel  struck 
with  sledge-hammers,  is  applied  successively  along  the  angle1 
formed  between  the  work  and  the  vice,  and  after  the  iron  has  been 
indented  the  whole  length,  the  blows  of  the  sledges  directed  on  the 
overhanging  piece  of  iron  complete  the  separation. 


THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 


Fig.  329  represents  the  plan,  and  Fig.  330  the  partial  vertical 
section  of  a  "  hydraulic  machine  for  cutting  off  copper  bolts." 

The  circle  in  Fig.  329  represents  the  cylinder  of  a  hydrostatic 
press,  which  is.  flattened  to  the  width  of  the  rectangular  bar  that  is 
fixed  alongside  of  the  cylinder,  the  two  being  enveloped  in  the  ex- 
ternal casting  which  is  shaded  in  the  section  Fig.  330,  and  resem- 
bles a  stunted  pillar  three  or  four  feet  high.  The  whole  of  the 
parts  are  traversed  by  nine  sets  of  holes  suitable  to  bars  from  f 
to  2  J  inches  diameter  ;  the  holes  where  they  meet  on  the  lines  b  b, 
are  furnished  with  annular  steel  cutters,  and  are  enlarged  outwards 
each  way  to  admit  the  work  more  easily. 

The  rod  r  r,  to  be  sheared,  is  introduced  whilst  the  holes  are 
directly  opposite  or  continuous,  and  the  men  then  pump  in  the  in- 
jection water  through  the  pipe  w;  it  acts  upon  the  annulus  or 
shoulder  intermediate  between  the  two  diameters  of  the  cylinder, 


Figs.  329 


330 


331 


333* 


causes  the  descent  of  the  latter  with  a  pressure  of  about  100  tons, 
and  forces  the  bar  asunder  very  quietly,  and,  from  the  annular 
form  of  the  cutters,  without  bruising  it.  When  the  bar  has  been 
cut  off,  the  injection  water  is  allowed  to  flow  out  from  beneath  the 
cylinder,  and  the  latter  is  raised  by  a  loaded  lever  beneath  the 
•floor  ready  for  the  next  stroke.  The  machine  is  far  more  econo- 
mical in  its  action  than  the  old  mode  of  cutting  off  the  copper 
bolts  with  a  frame  saw  used  by  hand,  and  the  storekeeper  in 
charge  of  the  bolts  can,  if  needful,  perform  the  entire  operation 
unassistedly,  although  usually  four  men  work  the  pair  of  one  inch 


rotary 
and  are 

pretty  generally  used.  In  the  best  form  of  the  instrument,  two 
spindles,  connected  together  by  toothed  wheels  of  equal  size,  have 
each  two  thin  disks  of  different  diameters,  which  are  opposed  to 
each  other,  that  is.  a  large  and  a  small  in  the  same  plane,  as  in  the 
diagram,  Fig.  331 ;  the  larger  disks  overlap  each  other  and  travel 
in  lateral  contact,  and  therefore  act  just  like  shears,  and  the  two 
disks  in  each  plane  meet,  or  rather  nearly  meet,  so  as  just  to  grasp 
between  them,  after  the  manner  of  flatting  the  rollers,  the  two 


SHEARS. 


369 


parts  of  the  strip  of  metal  which  have  been  severed,  and  by  carry- 
ing these  forward  they  continually  lead  the  yet  undivided  part  of 
.the  metal  to  the  edges  of  the  larger  disks,  which  in  this  manner 
quickly  separate  the  entire  strip  of  metal  into  two  parts. 

The  machine  requires  that  the  spindle  carrying  the  disks  should 
have  an  adjustment  for  lateral  distance,  as  in  flatting  rollers,  to 
adapt  their  degree  of  separation  to  the  thickness  of  the  metal  to 
be  sheared.  One  of  the  spindles  should  also  have  an  endlong 
adjustment  to  bring  the  disks  into  exact  lateral  contact,  and  the 
machine  requires  in  addition  a  fence  or  guide  fixed  alongside  the 
revolving  shears  to  determine  the  width  of  the  strips  cut  off'. 
Sometimes  the  two  smaller  disks  are  omitted,  and  the  larger  alone 
used,  as  in  Fig.  332  ;  the  circular  shears  are  then  somewhat  less 
exact  in  their  action,  but  perform  nevertheless  sufficiently  well  for 
most  purposes. 

Circular  or  rotary  shears  are  very  useful  for  shearing  plates  not 
exceeding  one-eighth  of  an  inch  thick,  and  one  of  the  advantages 
which  the  rotary  possesses  over  the  common  shears,  is  the  facititv 
with  which  curved  lines  may  be  followed,  on  account  of  the  small 
portion  of  the  disks  that  are  in  contact,  whereas  the  length  of  rec- 
tilinear shear  blades  prevents  their  ready  application  to  curves.  Of 
course  the  speed  at  which  the  machines  may  be  driven  depends  on 
the  nature  of  the  work,  and  if  the  cuts  are  straight  and  the  plates 
light,  the  velocity  of  the  shears  may  be  considerable. 

The  circular  shears,  or  splitting  rolls  used  in  the  works  where 
wrought-iron  is  manufactured,  are  composed  of  steel  disks  of  equal 
thickness,  but  of  two  diameters,  arranged  alternately  upon  two 
spindles,  as  in  Fig.  333,  so  as  at  one  action  to  split  thin  plates  of 
iron  of  about  6  inches  in  width  into  very  narrow  pieces  known  as 
nail  rods,  and  into  strips  from  half  to  one 
inch  wide,  designated  as  bundle  or  split  iron. 
Of  course  different  pairs  of  rolls  are  required 
for  every  different  width  of  the  strips  thus 
manufactured. 

The  anti-friction  cam  press,  invented  by 
David  Dick,  of  Meadville,  Pennsylvania,  is 
destined  to  become  of  great  use  to  the  metal- 
worker. This  press  is  much  more  easily  con- 
structed, and  can  be  supplied  for  much  less 
cost  than  that  of  Timothy  Brahman ;  it  also 
can  be  made  to  accomplish  its  work  with 
much  greater  expedition. 

There  are  many  arrangements  for  shears, 
punches,  and  presses  for  iron  and  steel,  one 
of  which  may  be  described  thus : 

A  A,  Fig.  334,  are  two  eccentric  wheels, 

and  B  is  a  roller  between.     C  C  are  two 

pair   of   sectors,    constituting    the    bearings 

of  the  axes  of  the  sectors.     The  axes  of  tl 

24 


the  sectors  are  of  the 


370 


THE    PRACTICAL   METAL-WOEKER'S   ASSISTANT. 


knife-edge  shape.     D  is  the  bearing,  and  E  is  the  follower  of  the 
sectors. 

This  combination,  Fig.  33-i,  is  inclosed  in  a  frame,  Fig.  335. 
The  centre  roller  B  is  made  to  revolve,  which  carries  by  its  trac- 
tion the  two  eccentric  wheels  A  A,  which  have  their  bearings  on 
the  faces  of  the  sectors,  which  are  transferred  the  length  of  their 
faces  right  and  left,  the  sectors  being  knife-edge  shaped  at  the  cen- 
tres of  motion  O  O,  which  revolve  with  very  little  friction.  When 
A  A  have  made  their  revolution  the  follower  R  will  have  moved 
the  sum  of  the  two  eccentrics. 


Figs.  335 


336. 


Fig.  336  is  a  side  view  with  one  side  of  the  frame  removed. 
A  press  constructed  in  this  way,  the  follower  moving  down  a 
spring  S,  may  be  used  to  return  the  moving  parts  when  the  press 
is  relaxed. 


CHAPTBK  XXI. 

PUNCHES. 


PUNCHES  USED  WITHOUT  GUIDES.— This  title  may,  at  the  first 
glance,  only  appear  to  possess  a  very  scanty  relation  to  the  tools 
used  in  mechanical  manipulation,  as  the  ostensible  purpose  of  a 
punch  may  be  considered  to  be  only  that  of  making  a  round  or 
square  hole  in  any  thin  substance.  But  it  frequently  happens  that 
the  small  piece  or  disk  so  removed  by  the  punch,  is  the  particular 


PUNCHES.  371 

object  sought,  and  some  of  the  very  numerous  objects  thus  made 
with  punches  assume  a  very  great  importance  in  the  manufacturing 
and  commercial  world,  as  will  perhaps  be  admitted  when  a  few  of 
these  are  referred  to. 

The  general  character  of  a  punch  is  that  of  a  steel  instrument, 
the  end  of  which  is  of  precisely  the  form  of  the  substance  to  be 
removed  by  the  punch,  and  which  instrument  is  forcibly  driven 
through  the  material  by  the  blow  of  a  hammer.  When  the  sub- 
ject is  entertained  in  a  moderately  extended  sense,  it  will  be  seen 
that  much  variety  exists  in  the  forms  of  the  punches  themselves, 
and  also  in  the  modes  by  which  the  power  whereby  they  are 
actuated  is  applied. 

So  far  as  relates  to  the  actual  edges  of  the  punches  by  which  the 
materials  are  severed,  they  may  be  classed  under  two  principal  di- 
visions, namely,  duplex  punches,  and  single  punches.  The  duplex 
punches  have  rectangular  edges  and  are  used  in  pairs,  often  just 
the  same  as  in  shears  for  metal.  The  single  punches  have  some- 
times rectangular  but  generally  more  acute  edges,  the  one  side 
being  mostly  perpendicular. 

The  single  punches  require  a  firm  support  of  wood,  lead,  tin,  cop- 
per, or  some  yielding  material,  into  which  the  edge  of  the  punch 
may  penetrate  without  injury,  when  it  has  passed  through  the 
material  to  be  punched. 

The  following  classification  has  been  attempted,  as  that  best  cal- 
culated to  throw  into  something  like  order  the  miscellaneous  instru- 
ments that  will  presently  be  more  or  less  fully  described. 

Punches  used  without  guides. 

Punches  used  with  simple  guides. 

Punches  used  in  fly  presses,  and  miscellaneous  examples  of  their 
products. 

Punching  machinery  used  by  engineers. 

It  would  be  hardly  admitted  that  a  carpenter's  chisel,  driven  by 
a  mallet  through  a  piece  of  card,  could  be  considered  as  a  punch, 
still  the  circular  punch  used  with  a  mallet  on  a  block  of  lead,  for 
cutting  out  circular  disks  of  cards  for  gun- wadding,  is  indisputably 
a  punch,  and  yet  scarcely  more  than  a  chisel  bent  round  into  a 
hoop.  The  gun-punch  is  formed  as  in  Fig.  337,  and  is  turned 
conical  without  and  cylindrical  within,  or  rather  a  little  larger  at 
the  top,  that  the  waddings  may  freely  ascend,  and  make  their  way 
out  at  the  top  through  the  aperture;  when,  however,  annular 
punches  exceed  about  2  inches  in  diameter,  it  is  found  a  stronger 
and  better  method  to  make  them  as  steel  rings,  attached  to  iron 
stems  or  centres  spread  out  at  the  ends  to  fill  the  rings,  as  in  Fig. 
338,  but  holes  are  then  required  to  push  out  the  disks  that  stick  to 
the  punch,  as  shown  by  the  section  beneath  the  figure  838. 

The  punch  used  in  cutting  out  wafers  for  letters  is-  nearly  simi- 
lar, it  being  formed  as  a  thin  cylindrical  tube  of  steel,  fitted  to  the 
end  of  a  perforated  brass  cone  having  at  the  top  two  branches  for 
the  cross  handle,  by  which  it  is  pressed  through  several  of  the 


372 


THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 


farinaceous  sheets,  and  as  the  wafers  accumulate  in  the  punch  they 
escape  at  the  top.  Confectioners  use  similar  cutters  in  making 
lozenges,  and  frequently  the  thin  steel  cutter  is  fixed  to  a  straight 
perforated  handle  of  wood.  The  lozenges. are  cut  out  singly  and 
with  a  twist  of  the  hand. 

When  the  disk  is  the  object  required,  the  punch  is  always  cham- 
ferred  exteriorly,  as  then  the  edge  of  the  disk  is  left  square  and  the 
external  or  wasted  part  is  bruised  or  bent ;  but  the  punch  is  made 
cylindrical  without,  and  conical  within,  when  the  annulus  or  exter- 
nal substance  is  required  to  have  a  keen  edge.  And  when  pieces 
such  as  washers,  or  those  having  central  holes,  are  required  in  card 
or  leather,  the  punches  are  sometimes  constructed  in  two  parts,  as 
shown  separated  in  Fig.  339,  the  inner  being  made  to  fit  the  outer 
punch,  and  their  edges  to  fall  on  one  plane ;  so  that  one  blow  effects 
the  two  incisions,  and  the  punches  may  then  be  separated  for  the 
removal  of  the  work,  should  it  stick  fast  between  the  two  parts  of 
the  instrument. 

Punches  of  irregular  and  arbitrary  forms,  used  for  cutting  out 
paper,  the  leaves  for  artificial  flowers,  the  figured  pieces  of  cloth 
for  uniforms  and  similar  things,  are  made  precisely  after  the  manner 
of  Fig.  337,  and  also  of  Fig.  338,  except  that  they  are  forged  in  the 


Figs.  337 


338 


339 


341. 


1   F    i 


solid,  or  without  the  loose  ring.  These  irregular  punches  are, 
however,  much  more  tedious  to  make  than  the  circular,  which 
admit  of  being  fashioned  in  the  lathe. 

Figured  punches  of  much  larger  dimensions  have  been  of  late 
used  for  cutting  out  the  variously  formed  papers  used  in  making 
envelopes  for  letters.  The  punch  or  cutter  is  sometimes  made  iu 
one  piece  as  a  ring  an  inch  to  an  inch  and  a  half  deep,  or  else  in 
several^  pieces  screwed  around  a  central  plate  of  iron,  and  when  the 
punch  is  sharp  it  is  really  forced  through  three  to  five  hundred 
thicknesses  of  paper,  by  the  slow  descent  of  the  screw  press  in 
which  it  is  worked.  Army  clothiers  use  similar  instruments  for 
cutting  out  the  leather  for  shoes  and  various  other  parts  of  military 
clothing,  and  several  of  these  punching  or  cutting  tools  are  often 
grouped  together. 

Proceeding  to  the  punches   used  for  metal,  those  having  the 


PUNCHES. 


373 


thinnest  edges  are  known  as  hollow  punches ;  they  are^turned  of 
various  diameters,  from  about  J  to  2  inches,  and  of  the  section 
Fig.  340 ;  they  are  always  used  on  a  block  of  lead,  and  sometimes 
for  two  or  three  thicknesses  at  a  time  of  tinned  iron,  copper,  or 
zinc,  Punches  341,  smaller  than  £  inch,  are  generally  solid,  quite 
flat  at  the  end,  and  are  also  used  on  a  block  of  lead,  which,  although 
it  gives  a  momentary  support,  yields  and  receives  into  its  surface 
the  little  piece  of  metal  punched  out  by  the  tool. 

Fig.  343  represents  the  punch  used  by  smiths  for  red-hot  iron ; 
the  tool  is  solid  and  quite  flat  at  the  end,  and  whether  it  is  round, 
square,  or  oblong  in  its  section,  as  for  producing  the  holes  repre- 
sented, it  is  parallel  for  a  short  distance,  then  gradually  enlarged, 
and  afterwards  hollowed  for  the  hazel  rod  by  which  it  is  surrounded 
to  constitute  the  handle.  The  smith's  punch  is  frequently  used 
along  with  a  bottom  or  bed  tool  known  in  this  case  as  a  bolster,  and 
which  has  a  hole  exactly  of  the  same  area  as  the  section  of  the 
punch  itself. 

Punches  when  used  in  combination  with  bolsters  are  clearly 
similar  in  their  action  to  the  shears  with  rectangular  edges,  as  will 


Figs.  342         343 


344 


be  seen  on  comparing  Figs.  342  and  343,  the  only  difference  being 
that  the  straight  blade  of  the  shears  is  to  be  considered  as  bent 
round  into  a  solid  circle  for  a  circular  punch,  or  converted  into  a 
square,  rectangular,  or  other  figure,  as  the  case  may  be  ;  but  every 
part  of  the  punch  should  meet  its  counterpart  or  the  bolster  in 
lateral  contact,  the  same  as  formerly  explained  in  reference  to  shears. 
This  supposes  the  tools  to  be  accurately  made  and  correctly  held 
by  the  smith,  but  which  is  somewhat  difficult,  because  the  bolster, 
the  work,  and  the  punch,  are  all  three  simply  built  up  loosely  upon 
the  anvil,  and  the  eye  can  render  but  little  judgment  of  their  rela- 
tive positions ;  the  punch  is  consequently  apt  to  be  misdirected  so 
as  to  catch  against  the  bolster  and  damage  both  tools.  The  mode 
sometimes  used  to  avoid  this  inconvenience  is  represented  in  Fig. 
344,  in  which  a  guide  is  introduced  to  direct  the  punch  ;  but  agreea- 
bly to  the  proposed  arrangement,  this  figure  will  be  more  fully 
explained  hereafter,  when  some  other  tools  of  a  lighter  description 
have  been  spoken  of. 


374 


THE   PRACTICAL    METALWORKER  3   ASSISTANT. 


Fig.  315  shows  a  punch  used  by  harp-makers  and  others  in  cut- 
ting long  mortises  in  sheet  metal.  The  punch  is  parallel  in  thick- 
ness, and  has  in  the  centre  a  square  point  from  which  proceed 
several  steps ;  this  punch  is  used  with  a  bolster  having  a  narrow 
slit  as  long  as  the  width  of  the  punch.  A  small  hole  is  first  drilled 
in  the  centre  of  the  intended  mortise  ;  the  first  blow  on  the  punch 
converts  this  into  a  square,  the  next  cuts  out  two  little  pieces  ex- 
tending the  hole  into  a  short  mortise,  and  each  successive  blow  cuts 
out  a  little  piece  from  each  end,  thereby  extending  the  mortise  if 
needful  to  the  full  width  of  the  punch.  From  the  graduated  action 
the  method  entails  but  little  risk  of  breaking  the  punch  or  bulging 
the  metal,  even  if  it  should  have  but  little  width.  Sometimes,  to 
make  the  punch  act  less  energetically  at  the  commencement  of 
its  work,  the  steps  at  the  point  are  made  smaller  both  in  height  and 
width  ;  the  serrated  edge  then  becomes  curved  instead  of  angular, 
as  shown. 

PUNCHES  USED  WITH  SIMPLE  GUIDES. — Beginning  this  part  of 
the  subject  with  the  tools  having  the  most  acute  edges,  we  have  to 
refer  to  the  punch  pliers,  Fig.  346,  fitted  with  round  hollow  punches 
for  making  holes  in  leather  straps  and  thin  materials.  Some  pliers 
of  this  kind  have  a  small  oval  punch,  terminating  in  a  chisel  edge, 
for  cutting  those  holes  that  have  to  be  passed  over  buttons  ;  and 
pliers  have  been  made  with  circular,  square  and  triangular  puncjaes 
for  the  cruel  practice  of  marking  sheep  in  the  ear.  In  all  these 
tools  the  punch  is  made  to  close  upon  a  small  block  of  ivory  or 
copper,  so  as  to  insure  the  material  being  cut  through  without 
injuring  the  punch. 

Another  example  of  slender  chisel-like  punches  is  to  be  seen  in 
the  machine  for  cutting  the  teeth  of  horn  and  tortoise-shell  combs. 
The  punch  or  chisel  is  in  two  parts,  slightly  inclined  and  curved  at 
the  ends,  to  agree  in  form  with  the  outline  of  one  tooth  of  the 
comb.  The  cutter  is  attached  to  the  end  of  a  jointed  arm,  moved 
up  and  down  by  a  crank,  so  as  to  penetrate  almost  through  the 
material,  and  the  uncut  portion  is  so  very  thin  that  it  splits  through 
at  each  stroke  and  leaves  the  two  combs  detached. 


Figs.  346 

D'    D     < 


347. 


& 


The  little  instrument  called  a  pen-making  machine,  is  another 
ingenious  example  of  punches  moving  on  a  joint.  It  is  repre- 
sented of  half  its  true  size,  and  ready  to  receive  the  pen,  in 
Fig.  347,  and  in  Fig.  348  the  two  cutters  are  shown  of  full  size  and 


PUNCHES.  375 

laid  back  in  a  right  line — although  in  reality  it  only  opens  to  a 
right  angle.  The  lower  half  has  a  small  steel  cutter  b,  pointed  to 
the  angle  of  the  nibs  of  the  pen,  and  fluted  to  the  curve  of  the 
quill  as  at  a ;  the  upper  cutter  d  is  made  as  an  inverted  angle  with 
nearly  vertical  edges,  as  seen  at  e,  which  exactly  correspond  with 
the  lower  cutter,  so  as  between  them  to  cut  the  shoulders  of  the 
pen.  The  upper  tool  also  carries  a  thin  blade  or  chisel,  which 
penetrates  nearly  through  the  quill  and  forms  the  slit. 

The  quill  having  been  pared  down  to  its  central  line,  is  inserted 
through  the  hollow  joint,  on  the  line  /,  and  the  cutters  being  very 
near  the  joint,  the  lever  on  being  closed  gives  abundant  power 
for  the  penetration  of  the  punches.  The  pen  requires  to  be  after- 
wards nibbed,  and  for  which  purpose  another  cutter  is  attached  to 
the  instrument,  which  has  likewise  an  ordinary  pen-blade,  so  as  to 
be  entirely  complete  in  itself. 

Passing  from  the  punches  with  guides  obtained  by  means  of 
joints,  and  actuated  by  the  pressure  of  the  fingers,  we  will  return 
to  Fig.  344,  on  page  373,  which  with  its  simple  guide  becomes  a 
very  effective  tool  sometimes  known  as  the  hammer  press,  in  con- 
tradistinction to  the  screw,  or  fly-press  to  be  hereafter  spoken  of. 

The  guide  in  the  contrivance,  Fig.  344,  is  a  strong  piece  of  iron 
attached  to  the  bottom  tool,  and  sufficiently  above  it  to  admit  the 
work  between  the  two.  Each  part  is  pierced  with  a  hole  of  ex- 
actly the  same  size,  and  accurately  formed  as  if  they  were  inter- 
rupted portions  of  the  same  hole.  The  punch  is  made  exactly  to 
fit  either  haie,  so  that  from  the  upper  it  receives  a  correct  guid- 
ance, and  it  therefore  cuts  through  the  material,  and  penetrates  the 
lower  piece,  with  a  degree  of  precision  arid  truth  scarcely  attain- 
able when  the  tools  are  unattached,  and  are  used  simply  upon  the 
anvil,  as  before  described. 

As  however  the  punch  mostly  sticks  tight  in  the  work,  it  is 
needful  to  turn  the  instrument  over,  and  drive  out  the  punch  with 
a  drift  a  little  smaller  than  the  punch,  and  on  which  account  punch- 
ing tools  of  this  kind  are  often  made  of  two  parallel  plates  of  steel 
firmly  united  by  screws  or  steady  pins,  yet  separated  enough  for 
the  reception  of  the  work,  and  frequently  contrivances  are  added 
to  guide  the  works  to  one  fixed  position,  in  order  that  any  number 
of  pieces  may  be  punched  exactly  alike. 

Thus  in  punching  circular  mortises,  as  in  the  half  of  a  pair  of 
inside  and  outside  callipers  a,  Fig.  349,  the  punch  c,  is  first  used  to 
produce  the  central  hole,  and  this  punch  is  then  left  in  the  bed  I, 
to  retain  the  work  during  the  action  of  the  second  punch  m,  by 
which  the  mortise  is  cut.  The  punch  m,  is  very  short,  to  avoid 
the  chance  of  its  being  broken,  and  it  is  also  narrow,  so  as  to  em- 
brace only  a  short  portion  of  the  mortise,  which  is  then  completed, 
with  little  risk  to  the  tool,  at  three  or  four  strokes,  whilst  the 
punch  c  serves  as  a  central  guide. 

Occasionally  also  punches  of  this  simple  kind,  but  on  a  l:iv 
scale,  have  been  placed  under  drop  hammers,  falling  from  a  COQ- 


376  THE   PRACTICAL   METAL-WORKEK'S   ASSISTANT. 

siderable  height  through  guide  rods,  somewhat  as  in  a  pile-driving 
machine.  This  mode  of  obtaining  power  is  not  suited  to  the  action 
of  punches  used  in  cutting  out  metals,  amongst  other  _  reasons,  be- 
cause the  punch  sticks  very  hard  in  the  perforation  ^  it  has  made, 
and  requires  some  contrivance  for  pulling  it  out,  which  is  not  so 
easily  obtained  in  this  apparatus  as  in  fly-presses,  that  are  suited 
alike  to  large  and  small  works. 

The  drop  hammer,  or  as  it  is  more  commonly  called  a  force,  is 
however  very  much  used  in  the  manufacture  of  stamped  wrorks, 
or  such  as  are  figured  between  dies,  of  which  an  example  is  de- 
scribed at  length  in  page  312.  Compared  with  a  fly-press  of  equal 
power,  the  force  is  less  expensive  in  its  first  construction,  but  it  is 
also  less  accurate  in  its  performance. 

Fig.  350  is  a  very  simple  yet  effective  tool,  which  may  be  viewed 
as  a  simplification  of  the  fly-press  i  it  consists  of  one  very  strong 
piece  of  wrought-iron,  about  one  inch  thick  and  four  or  five  inches 

Figs.  349  350. 


wide,  thickened  at  the  ends  and  bent  into  the  form  represented  ; 
the  one  extremity  is  tapped  to  receive  a  coarse  screw,  the  end  of 
which  is  formed  as  a  cylindrical  pin,  or  punch,  that  is  sometimes 
made  in  the  solid  with  a  screw,  but  more  usually  as  a  hardened 
steel  plug  inserted  in  a  hole  in  the  screw.  Immediately  opposite 
to  the  punch  is  another  hole  in  the  press,  the  -extremity  of  which 
is  fitted  with  a  hardened  steel  ring  or  bed  punch.  When  the  screw 
is  turned  round  by  a  lever  about  three  feet  long,  it  will  make  holes 
as  large  as  f  inch  diameter  in  plates  f  inch  thick,  and  is  therefore 
occasionally  useful  to  boiler  makers  for  repairs,  and  also,  for  fitting 
works  in  confined  situations  about  the  holds  of  ships,  and  other 
purposes.  When  this  screw  is  turned  backwards  the  punch  is 
drawn  out  and  relieved  from  the  work,  but  the  screwing  motion  is 
apt  to  wear  out  the  end  and  side  of  the  punch,  and  therefore  to 
alter  its  dimensions. 

A  very  convenient  instrument  of  exactly  the  same  kind  is  used 
in  punching  the  holes  in  leather  straps,  by  which  they  are  laced 
together  with  leather  thongs,  or  united  by  screws  and  nuts,  to  con- 
stitute the  endless  bands  or  belts  used  in  driving  machinery.  In 
this  case  the  frame  of  the  tool  is  made  of  gun-metal,  and  weighs 
only  a  few  ounces,  the  end  of  the  screw  is  formed  as  a  cutting 
punch,  and  it  is  perforated  throughout,  that  the  little  cylinders  of 


PUNCHES. 


377 


leather  may  work  out  through  the  screw,  which  only  requires  a 
cross  handle  to  adapt  it  to  the  thumb  and  fingers. 

In  this  case  the  screwing  motion  is  desirable,  as  the  punch  in 
revolving  acts  partly  as  a  knife,  and  therefore  cuts  with  great 
facility,  as  the  leather  is  supported  by  the  gun-metal  which  consti- 
tutes the  clamp  or  body  of  the  tool. 

PUNCHES  USED  IN  FLY-PRESSES,  AND  MISCELLANEOUS  EXAM- 
PLES OF  THEIR  PRODUCTS. — The  punches  used  in  fly-presses,  do 
not  differ  materially  from  those  already  described,  but  it  appears 
needful  to  commence  this  section  with  some  explanation  of  the 
principal  modifications  of  the  press  itself.  The  fly -press  is  a  most 
useful  machine,  which,  independently  of  the  punch  or  dies  where- 
with it  is  used,  may  be  considered  as  a  means  of  giving  a  hard, 
unerring  perpendicular  blow,  as  if  it  were  a  powerful  well-directed 
hammer.  The  precision  of  the  blow  is  attained  by  the  slide  where- 
by the  punch  is  guided,  the  force  of  the  blow  by  the  heavy  revolv- 
ing fly  attached  to  the  screw  of  the  press.  When  the  machine  is 
used,  the  fly  is  put  in  rapid  motion,  and  then  suddenly  arrested  by 
the  dies  or  cutters  coming  in  contact  witt  the  substance  submitted 
to  their  action.  The  entire  momentum  of  the  fly,  directed  by  the 
agency  of  the  screw,  is  therefore  instantaneously  expended  on  the 
work  to  be  punched  or  stamped,  and  the  reaction  is  frequently 
such  as  to  make  the  screw  recoil  to  nearly  its  first  position. 

The  bare  enumeration  of  the  multitude  of  articles  that  are  par- 
tially or  wholly  produced  in  fly-presses,  would  extend  \f>  consid- 
erable length,  as  this  powerful  and  rapid  auxiliary  is  not  only 
employed  in  punching  holes,  and  cutting  out  numerous  articles 
from  sheets  of  metal  and  other  materials,  but  also  in  moulding, 
stamping,  bending  or  raising  thin  metals  into  a  variety  of  shapes, 
and  likewise  in  impressing  others  with  devices,  as  in  medals  and 
coins. 

Fig.  351  represents  a  fly- 
press  of  the  ordinary  construc- 
tion that  is  used  for  cutting 
out  works,  and  is  thence  called 
a  cutting  press,  in  contra-dis- 
tinction  to  the  stamping  or 
coining  presses.  It  will  be 
seen  that  the  body  of  the 
press,  which  is  very  strong,  is 
fixed  upon  a  bed  or  base  that 
is  at  right  angles  to  the  screw ; 
the  latter  is  very  coarse  in  its 
pitch,  and  has  a  double  or 
triple  square  thread,  the  rise  of 
which  is  from  about  one  to  six 
inches  in  every  revolution. 
The  nut  of  the  screw  is  mostly 
of  gun-metal,  and  fixed  in  the 


Fig.  351. 


378  THE   PKACTICAL    METAL-WORKER'S   ASSISTANT. 

upper  part  or  head  of  the  press.  The  top  of  the  screw  is  square 
or  hexagonal,  .and  carries  a  lever  of  wrought  iron,  terminating  in 
two  solid  cast-iron  balls,  that  constitute  the  fly,  and  from  the  lever 
the  additional  piece  h,  descends  to  the  level  of  the  dies  to  serve  as 
the  handle,  so  that  the  left  hand  maybe  used  in  applying  the  material 
to  be  punched,  whilst  the  right  hand  of  the  operator  is  employed 
in  working  the  press. 

The  screw  is  generally  attached  to  a  square  bar  called  the  fol- 
lower, which  fits  accurately  dn  a  corresponding  aperture  and  is 
strictly  in  a  line  with  the  screw ;  and  to  the  follower  is  attached 
the  punch  shown  detached  at  a.  The  punch  is  sometimes  fitted 
into  a  nearly  cylindrical  hole,  and  retained  by  a  transverse  pin  or 
a  side  screw,  but  more  generally  the  die  is  screwed  into  the  fol- 
lower, like  the  chucks  of  some  turning  lathes ;  the  bed  or  bottom 
die  c,  which  is  made  strictly  parallel,  rests  on  the  base  of  the  press, 
and  is  retained  in  position  by  the  four  screws,  that  pass  through 
the  four  blocks  called  dogs;  these  screws,  which  point  a  little 
downwards,  allow  the  die  to  be  accurately  adjusted,  so  that  the 
punch  may  descend  inlp  it  without  catching  at  any  part,  and 
thereby  inflicting  an  injury  to  the  tools. 

The  piece  5,  which  rests  nearly  in  contact  with  the  die,  is  called 
the  puller  off,  it  is  perforated  to  allow  free  passage  to  the  punch ; 
when  the  latter  rises,  it  carries  up  with  it  for  a  short  distance  the 
perforated  sheet  of  metal  that  has  been  punched  through,  but 
which  is  held  back  by  the  puller  off,  whilst  the  punch  continuing 
its  ascent  rises  above  the  puller  off,  and  leaves  behind  the  sheet  of 
metal  so  released ;  the  sheet  is  again  placed  in  position  whilst 
another  piece  is  punched  out,  and  so  on  continually. 

Before  proceeding  to  speak  of  some  of  the  works  produced  in 
stamping  presses,  it  is  proposed  to  describe  some  of  the  points  of 
difference  met  with  in  fly -presses. 

The  body  of  a  cutting  press  is  in  general  made  with  one  arm, 
as  represented  in  Fig.  351,  because  the  sheet  of  metal  can  be  more 
freely  applied  to  the  die  ;  but  stamping  and  coining  presses,  which 
are  used  for  pieces  that  have  been  previously  cut  out,  require 
greater  strength  and  have  two  arms,  or  are  made  somewhat  as  a 
strong  lofty  bridge  with  the  screw  in  the  centre. 

The  fly  of  the  press  is  frequently  made  as  a  heavy  wheel,  which 
may  be  more  massive  and  is  less  dangerous  to  bystanders  than  the 
lever  and  balls,  and  in  large  presses  there  are  two,  three,  or  four 
handles  fixed  to  the  rim,  As  many  men  then  run  round  with  the 
fly,  and  let  go  when  the  blow  is  struck. 

Fly-presses  are  variously  worked  by  steam-power ;  thus  in  the 
mint  the  twelve  presses  for  cutting  out  the  blanks  or  disks  for 
coin,  are  arranged  in  a  circle  around  a  heavy  fly-wheel,  which  re- 
volves horizontally  by  means  of  the  steam-engine.  The  wheel  has 
one  projecting  tooth  or  cam,  which  catches  successively  the  twelve 
radial  levers  fixed  in  the  screws  of  the  presses,  to  cut  the  blanks, 
and  twelve  springs  immediately  return  the  several  levers  to  their 
first  positions,  ready  for  the  next  passage  of  the  cam  on  the  wheel 


PUNCHES. 


379 


The  fly  and  screw  are  also  worked  by  power,  in  some  cases  by 
an  eccentric  or  crank  movement  fixed  at  a  distance ;  a  long  con- 
necting-rod then  unites  the  crank  to  an  arm  of  the  wheel,  or  to  a 
straight  lever,  and  gives  it  a  reciprocating  movement. 

At  other  times,  in  place  of  the  crank  motion  are  ingeniously 
substituted  a  piston  and  cylinder  worked  after  the  manner  of  an 
oscillating  steam-engine,  if  we  imagine  the  boiler  to  be  superseded 
<by  a  large  chamber,  exhausted  by  the  steam-engine  nearly  to  a 
vacuum,  thus  constituting  an  air  engine,  the  one  side  of  the  piston 
being  opened  for  a  period  to  the  exhausted  chamber,  whilst  the 
other  receives  the  full  pressure  of  the  atmosphere. 

In  the  manufacture  of  steel  pens,  it  is  important  to  have  an 
exact  control  over  the  punches  which  cut  the  slits,  and  those  which 
mark  the  inscriptions,  as  by  descending  too  far  they  might  dis- 
figure the  steel,  or  even  cut  it  through.  Accordingly  there  is  in- 
troduced between  the  head  of  the  press  and  the  lever  an  adjusta- 
ble ring,  which  acts  as  a  stop,  and  only  allows  the  punches  to 
descend  to  one  definite  distance,  until  in  fact  the  ring  is  pinched 
between  the  press  and  lever. 

The  screw  of  the  fly-press  is  sometimes  superseded  by  a  contriv- 
ance known  both  as  the  toggle  joint,  and  as  the  knee  joint.  The 
two  parts  a,  b,  and  b,  c,  Fig.  352  are  joined  to  each  other  at  b,  the 


Pigs.  352 


extremity  a,  is  joined  to  the  upper  part  of  the  press,  and  c,  to  the 
top  of  the  follower.  When  the  parts  a,  b,  and  b,  c,  are  inclined  at 
a  small  angle,  the  extremities,  a,  and  c,  are  brought  closer  together, 
and  raise  the  follower,  but  when  the  two  levers  are  straightened,  a 
and  c  separate  with  a  minute  degree  of  motion,  but  almost  irre- 
sistible power,  especially  towards  the  completion  of  the  stroke. 
The  bending  and  straightening  of  the  toggle  joint  is  effected  by 
the  revolution  of  a  small  crank,  united  to  the  point  b,  Fig.  352,  by 
a  connecting  rod  b,f. 

Presses  with  the  toggle  joint  are  perfectly  suited  to  cutting  out 
works  with  punches  and  bolsters,  provided  the  relative  thickness 


380  THE   PRACTICAL   METAL-WORKEK'S  ASSISTANT. 

of  the  work  and  tools  are  such  as  to  bring  to  bear  the  strongest 
point  of  the  mechanical  action,  at  the  moment  the  greatest' resist- 
ance occurs  in  the  work ;  but  as  the  fly-press  with  a  screw  is  in  all 
cases  powerful  alike,  irrespective  of  such  proportions,  provided 
alone  that  there  is  sufficient  movement  to  create  the  required 
momentum,  the  fly-press  is  more  generally  useful 

The  cut  353  refers  to  a  lever  press  worked  by  an  eccentric,  and 
used  in  cutting  brads  and  nails,  which  will  be  again  alluded  to 
when  this  manufacture  is  briefly  noticed. 

It  is  now  intended  to  describe  a  few  examples  of  works  executed 
in  fly-presses,  giving  the  preference  to  those  appertaining  to 
mechanism. 

The  round  disks  of  metal  for  coin  are  always  cut  out  with  the 
fly-press,  and  are  then  called  blanks,  the  punch  being  a  solid 
cylinder,  the  bed  or  bolster  a  hollow  cylinder  that  exactly  fits  it. 
In  the  gold  currency,  more  especially,  great  care  is  taken  to  make 
these  punches  as  nearly  as  it  is  possible  mathematically  alike  in 
diameter,  and  the  sheets  of  gold  also  mathematically  alike  in  thick- 
ness, by  aid  of  the  drawing  rollers  or  rather  drawing  cylinders 
referred  to  in  page  327 ;  bat  notwithstanding  every  precaution, 
the  pieces  or  blanks  when  thus  prepared  do  not  always  weigh 
strictly  alike.  This  minute  difference  is  most  ingeniously  remedied 
by  using  the  one  error  as  a  compensation  for  the  other.  Trial  is 
made  at  each  end  of  every  strip  of  gold ;  and  by  cutting  the  thicker 
gold  with  the  smaller  punches,  the  adjustment  is  effected  with  the 
needful  degree  of  accuracy,  so  that  every  piece  is  made  critically 
true  in  weight,  without  the  tedious  necessity  for  weighing  and 
scraping,  otherwise  needful. 

Buttons  are  made  in  enormous  quantities  by  means  of  the  fly- 
press.  That  metal  buttons  should  be  thus  cut  out  with  tools  and 
stamped  with  dies,  will  be  immediately  obvious  to  all,  but  the  fly- 
press  has  been  also  more  or  less  employed  in  making  buttons  of 
horn,  shell,  wood,  papier-mache,  and  some  other  materials.  Amongst 
others,  may  be  noticed  the  silk  buttons,  called  Florentine  buttons, 
each  of  which  consists  of  several  pieces  that  are  cut  out  in  presses, 
then  enveloped  by  the  silk  covering,  and  clasped  together  at  the 
back  (in  the  press),  by  a  perforated  iron  disk,  the  margin  of  which 
is  formed  into  6  or  8  points  that  clutch  and  hold  the  silk,  whilst 
the  cloth  by  which  the  button  is  sewed  on,  is  at  the  same  time  pro- 
truded through  the  centre  hole  in  the  back  plate  of  the  silk  button; 
details  that  may  be  easily  inspected  by  pulling  one  of  them  to 
pieces.  Indeed  great  ingenuity  has  been  displayed,  and  many 
patents  have  been  granted,  for  making  this  necessary  article  of 
dress,  a  button. 

Bound  washers  that  are  placed  under  bolts  and  nuts  in  machin- 
ery, are  punched  out  just  like  the  blanks  for  coin ;  although  in 
punching  the  larger  washers,  that  measure  5  and  6  inches  in  diam- 
eter and  £  inch  thick,  with  the.  ordinary  fly-presses,  the  iron 
requires  to  be  made  red  hot. 


PUNCHES. 


381 


The  round  or  square  holes  in  the  washers  are  made  at  a  second 
process  with  other  tools,  and  to  insure  the  centrality  of  the  holes, 
some  kind  of  stop  is  temporarily  affixed  to  the  lower  tool.  The 
more  complete  stop  is  a  thin  plate  of  iron  hollowed  out  at  an  angle 
of  from  90  to  120  degrees  and  screwed  on  the  top  of  the  bed,  as  this 
may  be  set  forward  to  suit  various  diameters.  But  the  more  usual 
plan  is  to  drill  two  holes  in  the  bed,  to  drive  in  two  wires,  and  to 
bend  their  ends  flat  down  towards  the  central  hole,  as  also  shown 
in  Fig.'  354 ;  the  end  of  the  wires  are  filed  away  until,  after  a  few 
trials,  it  is  found  the  blank,  when  held  in  contact  with  the  stops 
by  the  left  hand,  is  truly  pierced ;  the  whole  quantity  may  be  then 
proceeded  with  as  rapidly  as  the  hands  can  be  used,  with  confi- 
dence in  the  centrality  of  all  the  holes  thus  produced. 

Chains  with  flat  links  that  are  used  in  machinery  are  made  in 
the  fly -press.  The  links  are  cut  out  of  the  form  shown  at  a,  Fig. 
355,  the  holes  are  afterwards  punched  just  as  in  washers  and  one  at 
a  time,  every  blank  being  so  held  that  its  circular  extremity  touches 
the  stops  on  the  bed  or  die,  and  thereby  the  two  holes  become  equi- 
distant in  all  the  links,  which  are  afterwards  strung  together  by 
inserting  wire  rivets  through  the  holes. 

The  pins  or  rivets  for  the  links  are  cut  off  from  the  length  of 
wire  in  the  fly-press,  by  a  pair  of  cutters  like  wide  chisels  with 
square  edges,  assisted  by  a  stop  to  keep  the  pins  of  one  length ; 
or  by  one  straight  cutter  and  an  angular  cutter  hollowed  to  about 
60  degrees ;  or  by  two  cutters  each  hollowed  to  90  degrees.  In 
the  three  cases,  the  wire  is  respectively  cut  from  two,  three,  or 
four  equidistant  parts  of  its  circumference :  semicircular  cutters 
are  also  used.  The  straight  cutters  first  named,  are  moreover  very 
usefully  employed  in  the  fly-press  for  many  of  the  smaller  works, 
that  would  otherwise  be  done  with  shears. 

Sometimes  the  succession  of  the  links  for  the  chain,  is  one  and 
two  links  alternately,  as  at  b,  Fig.  355  ;  at  other  times  3  and  2,  or 
4  and  3  links,  as  at  c,  and  so  forth  up  to  about  9  and  8  links  alter- 

Figs.  354  a  b  c 


:?r.7 


357. 


nately,  which  are  sometimes  used,  and  the  wires  when  inserted  are 
slightly  riveted  at  the  ends. 

The  pin  is  generally  the  weakest  part  of  the  chain  and  gives 
way  first,  but  in  the  chains  with  8  or  9  links,  the  pin  must  be  cut 
through  at  16  places  simultaneously,  before  the  chain  will  yield. 


382  THE    PRACTICAL    METAL-WORKER'S   ASSISTANT. 

Chains  are  sometimes  intended  to  catch  on  pins  or  projections, 
around  a  wheel  of  the  kind  shown  in  Fig.  357,  to  fulfil  the  office 
of  leather  bands,  without  the  possibility  of  the  slipping,  which  is 
apt  to  occur  with  bands  when  subjected  to  unusual  strains. 

Such  chains  are  made  after  the  manner  shown  in  Fig.  356  :  to 
constitute  the  square  openings  that  fit  over  the  pins  of  the  wheel, 
the  central  links  are  made  shorter,  by  which  means  the  apertures 
are  brought  closer  together  than  if  the  longer  links  were  used 
throughout.  Fig.  358  shows  a  different  kind  of  chain,  that  has 
been  used  for  catching  in  the  teeth  of  an  ordinary  spur-wheel  with 
epicycloidal  teeth :  this  chain  was  invented  by  John  Oldham,  Engi- 
neer to  the  Bank  of  Ireland. 

Chains  for  watches,  time-pieces,  and  small  machinery,  are  too 
minute  to  be  made  as  above  described,  therefore  the  slip  of  steel 
is  first  punched  through  with  the  rivet  holes  required  for  a  num- 
ber of  links,  by  means  of  a  punch  in  which  two  steel  wires  are 
inserted ;  the  distance  between  the  intended  links  is  obtained 
(somewhat  as  in  file  cutting)  by  resting  the  burrs  of  the  two  pre- 
vious holes  against  the  sharp  edge  of  the  bed  or  bolster.  ,The 
links  are  afterwards  cut  out  by  a  punch  and  bolster  of  the  kind 
already  noticed,  but  very  minute,  and  the  punch  has  two  pins  in- 
serted at  the  distance  of  the  rivet  holes,  the  slip  of  steel  being 
every  time  fitted  by  two  of  the  holes  to  these  pins ;  all  the  links 
are  thereby  cut  centrally  around  the  rivet  holes. 

The  tools  are  carried  in  a  thick  block  having  a  perpendicular 
square  hole,  fitted  with  a  stout  square  bar ;  the  latter  is  driven 
with  a  hammer,  which  is  supported  on  pivots,  raised  by  a  spring, 
and  worked  by  a  pedal ;  but  when  the  links  measure  from  J  to  ^ 
an  inch  in  length,  such  tools  are  worked  by  a  screw. 

The  punches  are  fitted  to  the  side  of  the  square  bar,  in  a  pro- 
jecting loop  or  mortise,  and  secured  by  a  wedge.  They  are  drilled 
with  holes  for  the  pins,  and  across  each  punch  there  is  a  deep 
notch  to  expose  the  reverse  ends  of  the  pins,  in  order  that  when 
broken  they  may  be  driven  out  and  replaced.  The  pins  are  taper 
pointed,  that  they  may  raise  burrs,  instead  of  cutting  the  metal 
clean  out,  and  being  taper,  no  puller-off  is  required,  and  the  bed 
tools  are  fitted  in  chamfer  grooves  in  the  base  of  this  old  yet  very 
efficient  instrument. 

A  large  chain  for  a  pocket  chronometer  now  before  the  author, 
measures  nearly  14  inches  in  length,  and  contains  in  every  inch  of 
its  length  22  rivets  and  also  33  links,  (in  three  rows) ;  the  total 
number  of  pieces  in  the  chain  is  therefore  770,  and  its  weight  is 
9  J  grains.  A  chain  for  a  small  pocket-watch  measures  6  inches  in 
length,  and  has  42  rivets  and  63  links  in  every  inch,  in  all  630 
pieces,  and  yet  the  entire  chain  only  weighs  one  grain  and  three- 
quarters. 

The  square  links  of  chains  for  jewelry  are  often  cut  out  with 
punches,  the  exterior  and  interior  being  each  rectangular ;  after 
which  each  alternate  link  is  slit  with  a  fine  saw  for  the  introduc- 


PUNCHES.  383 

tion  of  the  two  contiguous  links,  and  then  soldered  together  so 
that  the  gaps  become  filled  up.  Other  chains  are  drawn  as  square 
tubes,  and  cut  off  in  short  lengths  with  a  saw ;  these,  after  having 
been  strung  together,  are  often  drawn  through  a  draw-plate  with 
round  holes,  to  constitute  chains  which  preset  an  almost  continu- 
ous cylindrical  surface  like  round  wire  ;  a  Very  neat  manufacture, 
invented  in  France. 

The  teeth  of  saws  are  for  the  most  part  cut  in  the  fly-press. 
Teeth,  whether  large  or  small,  require  but  one  punch,  the  sides  of 
which  meet  at  60  degrees.  Two  studs  are  used  to  direct  the  edge 
of  the  blade  for  the  saw  to  the  punch,  at  the  required  angle  de- 
pending on  the  pitch  or  inclination  of  the  teeth,  and  an  adjustable 
stop  determines  the  space  or  interval  from  tooth  to  tooth,  by  catch- 
ing against  the  side  of  the  last  tooth  previously  made.  Gullet 
teeth,  and  the  various  other  kinds  shown,  require  punches  of  their 
several  compounded  figures,  and  of  different  dimensions  for  each 
size  of  tooth. 

The  teeth  of  circular  saws  are  similarly  punched  out  by  mount- 
ing the  perforated  circular  disk  on  a  pin  or  axis,  but  in  cutting  the 
last  six  or  eight  teeth,  it  is  needful  to  be  watchful,  so  as  to  divide 
the  remaining  space  into  moderately  equal  parts. 

In  cutting  the  teeth  of  circular  saws  not  exceeding  12  inches 
diameter,  Holtzapffel  and  Co.  have  been  in  the  habit  of  mounting 
the  steel  plates  on  a  spindle  in  a  lathe  with  a  dividing  plate,  and 
using  a  punch  and  bed  fitted  to  a  square  socket  fixed  horizontally 
in  the  ordinary  rest  or  support  for  the  turning  tool,  the  punch  being 
driven  through  the  plate  by  one  revolution  of  a  snail  or  cam,  by 
means  of  a  winch  handle,  and  thrown  back  by  a  spring.  In  this 
arrangement  the  dividing  plate  insures  the  exact  dimensions  and 
equality  of  the  teeth,  which  are  rapidly  and  accurately  cut. 
-The  copper  caps  for  percussion  guns  are  punched  out  in  the  form 
of  a  cross  with  short  equal  arms,  or  sometimes  in  a  similar  shape 
with  only  three  arms,  and  the  blanks,  after  having  been  annealed, 
are  thrown  out  into  form  by  means  of  dies,  which  fold  up  the  arms 
and  unite  them  to  constitute  the  tubular  part,  whilst  the  central 
part  of  the  metal  forms  the  top  of  the  cap  that  receives  the  com- 
position and  sustains  the  blow  of  the  hammer. 

Steel  pens  are  another  most  prolific  example  of  the  result  of  the 
fly-press ;  they  pass  through  the  hands  many  times,  and  require  to 
be  submitted  to  the  action  of  numerous  dies,  to  five  of  which  alone 
we  shall  advert.  The  blanks  are  cut  by  dies  of  the  usual  kind,  so 
as  in  general  to  produce  a  flat  piece  of  the  exterior  form  of 
Fig.  359,  page  384 ;  the  square  mortise  at  the  bottom  of  the  slit 
is  then  punched  through.  The  next  process  is  usually  to  strike  on 
the  blanks  the  maker's  name. 

The  slit  is  now  cut  by  a  thin  chisel-like  cutter,  which  makes  an 
angular  gap  nearly  through  the  steel,  from  that  side  of  the  metal 
intended  to  form  the  inner  or  concave  part  of  the  pen,  and  the  act 
of  curling  up  the  pen  into  the  channeled  form,  brings  the  angular 


384 


THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 


side  of  the  groove  into  contact,  rendering  the  slit  almost  invisible. 
The  slit,  which  is  as  yet  only  part  way  through  the  pen,  is  in 
general  completed  in  'the  process  of  hardening,  as  the  sudden 
transition  into  the  cooling  liquid  generally  causes  the  little  portion 
yet  solid  to  crack  through,  or  else  the  slit  remains  unfinished 
until  the  moment  the  pen  is  pressed  on  the  nail  to  open  and  ex- 
amine its  nibs. 

Lariviere's  perforated  plates  for  strainers,  lanterns,  meat  safes, 
colanders,  and  numerous  other  articles,  exhibit  great  delicacy  and 
accuracy  in  the  mode  in  which  they  are  punched  out.  The  tools 
are  illustrated  by  the  enlarged  sections,  Fig.  360.  The  punch  con- 
sists of  a  plate  of  steel  called  the  punch  plate,  which  is  in  some 


Figs.  359 


361. 


cases  pierced  with  only  one  single  line  of  equidistant  holes,  that 
are  countersunk  on  their  upper  extremities.  Every  hole  is  filled 
with  a  small  cylindrical  punch  made  of  steel  wire,  the  end  of 
which  is  bumped  up,  or  upset  to  form  a  head,  that  fills  the  chamfer 
in  the  punch  plate,  so  that  the  punch  cannot  be  drawn  out  by  the 
work  in  the  ascent  of  the  press.  The  bed  punch  or  matrix  has  a 
number  of  equidistant  holes  corresponding  most  exactly  with  the 
punches.  In  this  case  the  holes  in  the  work  are  punched  out  one 
line  at  a  time,  and  between  each  descent  of  the  punches  the  sheet 
of  metal  is  shifted  laterally  by  a  screw  slide  until  it  is  in  proper 
position  to  receive  the  adjoining  line  of  holes. 

At  other  times,  the  tool,  instead  of  having  only  one  line  of 
punches,  is  wide,  and  entirely  covered  with  several  lines,  so  as  to 
punch  some  hundreds  or  even  thousands  of  holes  at  one  time. 
For  circular  plates  the  punches  are  sometimes  arranged  in  one 
radial  line,  but  more  usually  the  whole  of  the  punches  required  for 
the  fourth,  sixth  or  eighth  part  of  the  circular  disks  are  placed  in 
the  form  of  a  sector,  and  the  central  hole,  having  been  first 
punched,  is  made  to  serve  as  the  guide  for  the  four,  six  or  eight 
positions  at  which  these  beautiful  tools  are  applied. 

Many  of  the  thin  plates  thus  punched  require  to  be  strained  like 
the  head  of  a  drum  to  keep  the  metal  flat,  in  which  case  the  metal 
is  grasped  between  little  clamps  or  vices  around  its  four  edges,  and 
then  stretched  by  appropriate  screws  and  slides  with  which  the 
apparatus  is  furnished,  and  the  same  mechanism  prevents  the  metal 
from  rising,  and  therefore  fulfils  the  office  of  the  puller-off  com- 
monly used  with  punches. 


PUNCHES.  385 

The  construction  of  the  tools  above  described  calls  for  the  great- 
est degree  of  precision.  The  drill  employed  to  pierce  the  punch 
and  matrix  is  of  exceedingly  small  size  in  the  finest  perforated 
works,  as  it  is  said  as  many  as  six  or  seven  hundred  holes  have 
been  inserted  in  the  length  of  six  inches,  which,  considering  the 
intervening  spaces  to  be  half  as  wide  as  thS  diameter  of  the  holes, 
would  make  the  latter  of  the  minute  size  of  only  six-thousandths 
of  an  inch  diameter.  Such  finely  perforated  metal  appears  to  offer 
nearly  the  transparency  of  muslin,  and  is  a  manifest  proof  of  the 
great  skill  displayed  in  the  construction  of  the  instruments,  and  in 
conducting  the  entire  process. 

M.  Marc  Lariviere's  patent  was  granted  28th  Nov.,  1825,  and  is 
described  in  the  Repertory  of  Patent  Inventions,  vol.  iii.,  3d  series, 
page  182. 

All  the  foregoing  examples  of  punched  works  suppose  the  punch 
to  have  been  faced  to  the  follower  of  the  press,  and  the  matrix  to 
the  base  of  the  same,  in  which  case  the  bed  punch  requires  to  be 
very  exactly  adjusted  by  the  set  screws  or  dogs  of  the  press.  But 
it  remains,  in  concluding  this  section,  to  advert  to  a  different 
arrangement,  in  which  the  cutting  tools  are  quite  detached,  and  are 
far  less  liable  to  accident  or  fracture,  even  when  the  punches  are 
of  very  large  area  and  complicated  figure,  than  when  constructed 
in  the  ordinary  manner  with  a  shank,  by  which  they  are  united  to 
the  follower  of  the  press. 

Punches,  to  be  used  in  this  manner,  for  works  with  various  de- 
tached apertures  requiring  any  especial  arrangement,  and  for 
various  straggling  and  complicated  objects,  are  constructed  as'shown 
in  Figs.  362  to  36-i.  There  are'  two  steel  plates  somewhat  larger 
than  the  work,  and  from  T3g  to  |  thick,  the  plates  are  hinged 
together  like  the  leaves  of  a  book,  but  are  placed  sufficiently  distant 
to  admit  between  them  the  work  to  be  stamped  out  and  which  is 
pinched  between  them  by  a  thumb  screw  a.  The  two  plates  whilst 
folded  together  are  perforated  with  all  the  apertures  required  in 
the  work,  which  perforation  may  be  either  detached,  continuous  or 
arranged  in  any  ornamental  design  that  may  be  required.  To  all 
the  apertures  are  fitted  punches,  which  in  length  or  vertical  height 
are  about  one-eighth  of  an  inch  longer  than  the  thickness  of  the 
upper  plate,  so  as  to  stand  up  one-eighth  when  resting  on  the  ma- 
terial to  be  punched,  as  seen  in  the  partial  section  364,  in  which  the 
work  is  shaded  obliquely  and  the  punch,  vertically. 

As  it  would  be  difficult  to  fit  the  punches  in  one  single  piece  to 
the  ornamental  or  straggling  parts  of  some  devices,  and  as  moreover 
such  large  and  complicated  punches  would  be  almost  sure  to  become 
distorted  in  the  hardening,  or  broken  when  in  use,  the  difficulty  is 
boldly  met  by  making  the  punch  of  as  many  small  pieces  as  cir- 
cumstances may  render  desirable,  but  which  pieces  must,  collectively 
fill  up  all  the  interstices  of  the  plate. 

In  using  these  punching  tools,  it  is  onlv  necessary  first  to  fix 
between  the  plates  the  metal  to  be  pierced,  then  to  insert  all  the 
25 


386  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

punches  into  their  respective  apertures,  and  lastly  to  give  the  whole 
one  blow  between  the  flat  disks  of  a  powerful  fly-press ;  this  drives 
all  the  punches  through  the  work,  and  leaves  them  flush  with  the 
upper  surface.  The  whole  is  then  removed  from  the  press,  and 
placed  over  an  aperture  in  the  work  bench,  and  with  a  small  drift 
and  hammer  the  punches  are  driven  out  of  the  plates  into  a  drawer 
beneath,  and  on  the  plates  being  separated,  the  work  will  be  found 
to  be  exactly  perforated  to  the  same  design  as  that  of  the  tool  itself ; 
or  with  any  part  of  the  design  instead  of  the  whole,  if  part  only  of 
the  punches  were  inserted  in  their  respective  places.  The  punches 
are  selected  from  amidst  the  corresponding  pieces  of  brass,  which 
latter  are  laid  on  one  side  and  the  routine  is  recommenced. 

It  is  by  this  ingenious  application  of  punches  that  the  beautiful 
buhl  works  of  the  late  Robert  B.  Henesey,  of  Holborn,  London, 
were  stamped.  If  a  honeysuckle  should  be  the  device,  the  piece 
of  brass  is  first  placed  between  the  plate  and  punched  out,  and  pro- 
vided the  punches  are  of  the  same  length,  the  honeysuckle  is  re- 
moved in  one  piece  although  the  punch  may  be  in  several ;  the  wood 
is  afterwards  inserted,  and  is  punched  to  exactly  the  same  form,  so 
that  the  brass  honeysuckle  will  be  found  to  fit  in  the  most  perfect 
manner,  as  it  is  an  exact  counterpart  of  the  removed  wood. 

The  process  is  very  economical  and  exact,  but  is  only  suited  to 
large  designs,  because  of  the  injury  it  would  otherwise  inflict  on 
the  wood,  and  on  account  of  the  expense  of  the  tools,  the  mode  is 
only  proper  for  those  patterns  of  which  very  large  numbers  are 
wanted ;  whereas  the  buhl  saw  is  not  liable  to  these  limitations,  but 
is  of  universal,  although  less  rapid  application. 


Figs.  362 


363 


365 


366. 


Out  brads  and  nails,  or  those  which,  instead  of  being  forged,  are 
cut  out  of  sheet  iron  by  machinery,  constitute  the  last  example  it 
is  proposed  to  advance  in  this  section. 

Brads  of  the  most  simple  kind,  as  in  Fig.  365,  have  no  heads, 
but  are  simply  wedge  form,  and  are  cut  out  of  strips  of  sheet  iron, 
equal  in  width  to  the  length  of  the  brads :  these  strips  are  slit  with 
circular  shears,  transversely  from  the  ends  of  the  sheets  of  iron,  so 
that  the  fibre  of  the  iron  may  run  lengthways  through  the  nails. 

When  such  brads  are  cut  in  the  fly-press,  the  bed  has  a  rectangu- 


PUNCHES.  387 

lar  mortise  shown  by  the  strong  black  line  in  Fig.  365,  the  punch 
is  made  rather  long  and  rectangular  so  as  exactly  to  fill  the  bed, 
but  the  last  portion  of  the  punch,  say  for  half  an  inch  of  its  length, 
is  nicked  in,  or  filed  back  exactly  to  the  size  and  angle  of  the  brad, 
as  shown  in  the  inverted  plan,  in  which  the  shaded  portion  shows 
the  reduced  part  or  tail  of  the  punch.  The  punch  is  never  raised 
entirely  out  of  the  bed,  in  order  that  the  strip  of  metal  may  be  put 
so  far  over  the  hole  in  the  bed  as  the  tail  of  the  punch  will  allow 
it,  and  also  in  contact  with  a  stop  or  pin  fixed  to  the  bed,  and  in 
the  descent  of  the  punch  its  outer  or  rectangular  edge  moves  the 
brad. 

The  strip  of  metal  is  turned  over  between  every  descent  of  the 
press,  so  as  to  cut  the  head  of  the  one  brad  from  the  point  of  that 
previously  made,  and  the  double  guides  afforded  by  the  tail  and 
stop  enable  this  to  be  very  quickly  and  truly  done.  The  upper 
surface  of  the  bed  is  not  quite  horizontal  but  a  little  inclined,  so 
that  the  cutting  may  commence  at  the  point  of  the  brad,  and  thereby 
curl  it  less  than  if  the  tools  met  in  absolute  parallelism. 

In  cutting  brads  that  have  heads,  the  general  arrangements  are 
somewhat  different,  as  explained  in  the  diagram  Fig.  366,  in  which 
as  before,  the  rectangular  aperture  in  the  bottom  tool  is  bounded 
by  the  strong  black  line,  the  tail  of  the-  punch  is  shaded,  the  stop  s, 
is  situated  as  far  beyond  the  aperture  in  the  bed  as  the  vertical 
height  of  the  head,  and  it  is  so  made  that  the  small  part  which  ex- 
tends to  the  right,  overhangs  the  slip  of  iron  that  is  being  cut,  after 
the  manner  of  a  puller-off ;  but  the  overhanging  part  only  comes 
into  action  when  the  slip  is  tilted  up,  either  by  accident,  or  from 
being  so  short  as  to  give  an  insufficient  purchase  for  the  hand.  It 
is  also  to  be  observed  that  the  width  of  the  point  of  the  brad  is  just 
equal  to  the  projection  of  its  head. 

On  the  end  of  the  strip  of  iron  being  first  applied,  a  wedge-form 
piece  is  cut  off,  exactly  equal  to  the  difference  between  the  tail  of 
the  punch  and  the  bed,  and  a  little  projection  is  left  near  s,  and 
which  projection,  after  the  iron  is  turned  over,  rests  against  the  tail 
of  the  punch,  as  shown  in  the  figure,  so  that  the  succeeding  cut  re- 
moves the  one  brad  and  forms  the  head  of  the  following ;  the  tail 
of  the  punch  being  inclined  to  the  precise  angle  drawn  from  the 
point  to  the  head  of  the  brad,  as  denoted  in  the  diagram. 

When,  as  it  is  more  usual,  brads  are  cut  out  by  steam-power,  the 
cutters  are  not  worked  in  a  fly-press,  but  the  moving  cutter  is  com- 
monly fixed  at  the  end  of  a  long  arm  which  is  moved  rapidly  up 
and  down  by  a  crank ;  the  strip  of  metal  is  held  in  a  spring  clarnp, 
terminating  in  a  long  iron  rod  which  rests  in  a  Y  or  fork,  so  that 
the  boy  who  attends  the  machine,  can  turn  the  metal  over  very 
rapidly  between  every  alternation  of  the  machine ;  these  particulars 
are  shown  in  Fig.  353. 

The  machine,  Fig.  353,  may  be  used  for  brads  either  with  or 
without  heads ;  it  is,  however,  always  necessary  to  turn  the  iron 
over  between  every  cut ;  but  in  the  toggle  press,  Fig.  352,  and 


388  THE   PKACTICAL   METAL-WORKER'S   ASSISTANT. 

which  acts  much  more  quickly,  it  is  not  requisite  to  reverse  the 
metal,  as  the  entire  press  is  moved  on  its  pivots  e  e,  by  the  rod  g, 
so  as  to  incline  the  press  alternately  to  the  right  and  left,  to  the 
angle  of  such  nails  as  are  simply  wedge-form,  or  have  no  heads,  as 
in  Fig.  365,  page  386. 

In  some  machines  resembling  Fig.  353,  the  nail  as  soon  as  cut 
off  is  grasped  in  a  pair  of  forceps  or  dies,  whilst  a  hammer,  also 
moved  by  the  machine,  strikes  a  blow  that  upsets  the  metal,  and 
constitutes  the  flat  head  in  the  kinds  known  as  cut  nails,  and 
tacks. 

PUNCHING  MACHINERY  USED  BY  ENGINEERS.— After  the  re- 
marks offered  on  pages  364  to  367,  on  shearing  tools,  little  remains 
to  be  said  in  this  place  on  the  punching  machinery  used  by  engi- 
neers, as  it  was  there  stated  that  the  cutters  for  shearing  and  the 
punches,  were  most  usually  combined  in  the  same  machine ;  the 
punch  being  placed  either  at  the  outer  extremity  of  the  jointed 
lever,  or  at  the  bottom  of  the  slide  in  those  machines  having  rec- 
tilinear action.  The  punch  is  fixed  to  the  slide  or  moving  piece, 
the  die  is  secured  to  the  framing  by  means  of  four  holding  and  ad- 
justing screws  just  as  in  fly-presses,  and  the  puller  off'  or  stop  is 
likewise  added,  all  which  details  are  represented  in  the  woodcuts 
on  pages  365  and  366. 

The  principal  application  of  the  engineer's  punching  engine,  is 
for  making  the  rivet-holes  around  the  edges  of  the  plates  of  which 
steam-boilers,  tanks,  and  iron  ships  are  composed.  Another  im- 
portant use,  and  in  which  the  punches  trench  upon  the  office  of  the 
shears,  is  in  cutting  out  curvilinear  parts  and  apertures  or  panels 
in  boiler  work,  to  which  straight  bladed  shears  cannot  be  applied. 
In  this  case  the  round  punch  is  used  in  making  a  series  of  holes 
running  into  one  another,  along  the  particular  line  to  be  sheared 
through,  or  in  other  words  the  punch  is  used  as  a  gouge,  by  which 
the  hole  that  has  been  first  formed,  is  extended  by  cutting  away 
crescent-form  pieces,  thus  leading  the  incision  in  any  required 
direction. 

This  employment  of  the  punch  to  shearing  curved  lines,  is.  also 
much  used  in  cutting  out  the  side  plates  of  the  framings  of  loco- 
motive engines,  which  consist  of  two  pieces  of  stout  boiler  plate 
(the  technical  name  for  iron  in  sheets  from  £  to  f  inch  thick),  riveted 
alongside  a  central  piece  of  wood,  that  is  sometimes  also  covered 
above  and  below  with  iron,  all  the  parts  being  united  by  rivets. 
The  punching  engine  serves  admirably  for  cutting  out  all  the  curved 
lines  in  these  side  plates,  also  the  spaces  where  the  bearings  for  the 
wheels  are  situated,  and  various  apertures. 

Fig.  367  is  a  slotting  and  paring  machine  manufactured  at  the 
Lowell  Machine  Shop,  Mass.  The  base  plate  and  upright  frame 
are  of  cast-iron.  The  tool  bar  moves  by  an  adjustable  crank  of 
ten-inch  stroke.  It  will  range  over  a  wheel  of  four  feet  diameter. 
Work  may  be  executed  by  a  circular  or  straight  line  movement. 
The  tool  is  made  self-acting,  and  inclines,  when  necessary,  from  a 


PUNCHES. 


389 


horizontal  position  to  cut  key  grooves  in  tapering  holes.  The  table 
apparatus  is  adjustable  up  and  down  in  front  of  the  frame  by  means 
of  a  rack,  pinion  worm,  and  worm-wheel. 

Fig.  367. 


In  England  the  name  of  the  inventor  is  suppressed  of  a  very  great 
improvement  in  the  punching  engine,  as  applied  to  making  boilers 
and  tanks,  in  which  the  rivet-holes  are  usually  required  to  be  made 
in  straight  lines,  and  at  exactly  equal  distances,  so  that  holes  in  two 
pieces  punched  separately  may  exactly  correspond. 

The  plate  was  fixed  down  upon  a  long  rectilinear  slide  or  car- 
riage, and  during  every  ascent  of  the  punch,  was  advanced  by  the 
machine  itself  the  interval  from  hole  to  hole,  the  moment  after  the 
punch  was  disengaged  from  the  work.  Subsequently  2,  3,  or  4 
punches  were  fixed  at  equal  distances  in  the  vertical  slide,  but  the 
punches  were  made  of  unequal  lengths,  so  that  they  came  succes- 
sively into  action,  thereby  dividing  the  strain,  and  the  horizontal 
slide  was  consequently  shifted  every  time,  a  distance  equal  to  2,  3, 
or  4  intervals.  This  machine,  which  displayed  much  ingenuity 
of  invention,  served  as  the  foundation  of  the  more  simple  punch- 
ing engines  that  are  now  met  with.  We  believe  the  invention  to 
be  by  M.  Cave*  of  Paris. 

The  following  experiments  were  performed  with  a  cast-iron 
lever,  11  feet  long,  multiplying  the  strain  ten  times,  with  a  screw 


690  THE  PEACTICAL   METAL-WORKER'S   ASSISTANT. 

adjustment  at  the  head,  and  a  counterpoise.  The  sheets  of  iron 
and  copper  which  were  experimented  upon,  were  placed  between 
two  perforated  steel  plates,  and  the  punch,  the  nipple  of  which  was 
perfectly  flat  on  the  face,  being  inserted  into  a  hole  in  the  upper 
plate,  was  driven  through  by  the  pressure  of  the  lever. 

The  average  results  of  the  several  experiments  (which  are  given 
in  a  detailed  tabular  form),  show  that  the  power  required  to  force 
a  punch  half  an  inch  diameter  through  copper  and  iron  plates,  is 
as  follows : 

Iron  plate      0.08  thick,  required  a  pressure  of  6,025  pounds. 
0.17  "  "  11,950 

0.24  "  "  17,100       " 

Copper  plate  0.08  "  "  3,983 

0.17  "  "  7,883       " 

Hence  it  is  evident  that  the  force  necessary  to  punch  holes  of 
different  diameters  through  metal  of  various  thicknesses,  is  directly 
as  the  diameter  of  the  holes  and  the  thickness  of  the  metal.  A 
simple  rule  for  determining  the  force  required  for  punching  may 
be  thus  deduced.  Taking  one  inch  diameter  and  one  inch  in  thick- 
ness as  the  units  of  calculation,  it  is  shown  that  150'00  is  the  con- 
stant number  for  wrought-iron  plates,  and  96*000  for  copper  plates. 
Multiply  the  constant  number  by  the  diameter  in  inches,  and  by 
the  thickness  in  inches ;  the  product  is  the  pressure  in  pounds,  that 
will  be  required  to  punch  a  hole  of  a  given  diameter  through  a 
plate  of  a  given  thickness. 

It  was  observed  that  the  duration  of  pressure  lessened  consider- 
ably the  ultimate  force  necessary  to  punch  through  metal,  and  that 
the  use  of  oil  on  the  punch  reduced  the  pressure  about  8  per  cent. 
A  drawing  of  the  experimental  lever  and  apparatus  accompanied 
the  communication. 

The  second  experiments  were  by  means  of  a  hydrostatic  press 
having  four  cylinders  in  combination,  punching  through  various 
pieces  of  iron ;  the  thickest  of  them  measured  3£  inches  thick,  and 
from  which  was  punched  out  a  disk  of  8  inches  diameter,  with  a 
pressure  of  2000  tons. 

The  removed  piece  was  rather  thinner  than  the  remainder  and  a 
little  taper,  which  arose  from  the  circumstance  of  the  bolster  hav- 
ing been  purposely  made  with  a  flat  bottom,  and  a  little  larger  in 
diameter  than  the  punch,  so  that  the  disk  when  removed  was  a 
little  spread  or  flattened  out. 

It  is  curious  that  experiments  so  distant  from  one  another  in 
their  scale  of  proportion,  should  yet  agree  so  nearly : 

The  computed  force  is  .  .  150,000  x    8x      3| =4,200, 000  Ibs. 
The  actual  force  was  ...       2000  x  20  x  112  =4,480,000  Ibs. 

Figure  368  is  an  upright  drill,  manufactured  at  the  Lowell  ma- 
chine shop,  Lowell,  Mass.,  and  invented  by  W.  B.  Bennet,  who  has 
invented  many  other  useful  metal-worker's  tools. 


PUNCHES. 


391 


The  base  and  frame  are  of  cast-iron ;  the  table  that  holds  the 
work  is  elevated  or  depressed  by  a  screw ;  the  drill  feeds  down  by 
hand;  the  drilling-shaft  has  four  changes  of  speed,  and  geared 

Fig.  368. 


with  iron  cone  pulleys.  This  instrument  will  drill  a  hole  ten 
inches  from  the  nearest  edge  of  the  object  operated  upon,  and  six 
inches  deep. 

Fig.  369  is  the  Universal  Drilling  Machine,  manufactured  at  the 
Lowell  Machine  Shop,  Lowell,  Mass.,  of  which  establishment  Wm. 
A.  Burke  is  superintendent. 

This  machine  is  designed  for  drilling  pieces  of  castings,  which, 
from  their  size,  cannot  be  operated  upon  by  drilling  machines  of 
the  ordinary  kinds.  It  consists  of  a  very  strong  upright  frame  or 
column,  which  carries  upon  its  front  side  a  heavy  beam  or  arm, 
that  can  be  moved  out  from  the  column  to  the  distance  of  8  feet. 
This  beam  has  also  a  movement  up  or  down  of  6  feet,  upon  the 
front  of  the  column.  It  also  carries  upon  its  extreme  outer  end 
the  drill  headstock.  The  spindle  in  this  headstock  is  driven  by 
means  of  bevel  gears  and  shafts  from  the  first  driving  shaft.  A 


392 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 


hole  can  be  drilled  in  a  piece  8  feet  distant  from  the  nearest  side 
or  edge,  and  a  piece  can  be  brought  under  the  drill  6  feet  in  height. 

Fig.  369. 


The  headstock  and  spindle  are  made  adjustable,  so  that  the  whole 
can  be  drilled  at  any  angle  required,  and  ten  inches  deep.  The 
driving  shaft  with  cast-iron  pulleys  is  attached  to  the  frame.  The 
machine  is  back  geared,  giving  8  different  speeds  to  the  drill. 


CHAPTEE  XXII. 

DRILLS. 

DRILLS  FOR  METAL,  USED  BY  HAND. — The  frequent  necessity, 
in  metal  works,  for  the  operation  of  drilling  holes,  which  are  re- 
quired of  all  sizes  and  various  degrees  of  accuracy,  has  led  to  so 
very  great  a  variety  of  modes  of  performing  the  process,  that  it  is 
difficult  to  arrange  with  much  order  the  more  important  of  these 
methods  and  apparatus. 

The  ordinary  piercing  drills  for  metal  do  not  present  quite  so 
much  variety  as  the  wood  drills.  The  drills  for  metal  are  mostly 
pointed ;  they  consequently  make  conical  holes,  which  cause  the 
point  of  the  drill  to  pursue  the  original  line,  and  eventually  to 
produce  the  cylindrical  hole.  The  comparative  feebleness  of  the 
drill-bow  limits  the  size  of  the  drills  employed  with  it  to  about 
one-quarter  of  an  inch  in  diameter ;  but  as  some  of  the  tools  used 
with  the  bow  agree  in  kind  with  those  of  much  larger  dimensions, 
it  will  be  convenient  to  consider  as  one  group  the  forms  of  the 
edges  of  those  drills  which  cut  when  moved  in  either  direction. 


DRILLS. 


893 


Figs.  370,  371,  and  372,  represent,  of  their  largest  sizes,  the 
usual  forms  of  drills  proper  for  the  reciprocating  motion  of  the 
drill  bow,  because,  their  cutting  edges  being  situated  on  the  line 
of  the  axis,  and  chamfered  on  each  side,  they  cut,  or  rather  scrape, 
with  equal  facility  in  both  directions  of  motion. 

Fig.  370  is  the  ordinary  double-cutting  drill,  the  two  facets 
forming  each  edge  meet  at  an  angle  of  about  50  to  70  degrees,  and 
the,  two  edges  forming  the  point  meet  at  about  80  to  100 ;  but  the 
watch-makers,  who  constantly  employ  this  kind  of  drill,  sometimes 
make  the  end  as  obtuse  as  an  angle  of  about  120  degrees ;  the 
point  does  not  then  protrude  through  their  thin  works  long  before 
the  completion  of  the  hole.  Fig.  371,  with  two  circular  chamfers, 
bores  cast-iron  more  rapidly  than  any  other  reciprocating  drill,  but 
it  requires  an  entry  to  be  first  made  with  a  pointed  drill.  By 
some  this  kind  is  also  preferred  for  wrought-iron  and  steel.  The 
flat-ended  drill,  Fig.  372,  is  used  for  flattening  the  bottoms  of  holes. 
Fig.  373  is  a  duplex  expanding  drill,  used  by  the  cutlers  for  in- 
laying the  little  plates  of  metal  in  knife  handles;  the  ends  are 
drawn  full  size. 


Figs.  370 


374 


375. 


Fig.  374  is  also  a  double-cutting  drill ;  the  cylindrical  wire  is 
filed  to  the  diametrical  line,  and  the  end  is  formed  with  two  facets. 
This  tool  has  the  advantage  of  retaining  the  same  diameter  when 
it  is  sharpened.  It  is  sometimes  called  the  Swiss  drill,  and  was 
employed  by  M.  Le  Riviere,  for  making  the  numerous  small  holes 
in  the  delicate  punching  machinery  for  manufacturing  perforated 
sheets  of  metal  and  pasteboard.  These  drills  are  sometimes  made 
either  semi-circular  or  flat  at  the  extremity. 

The  square  countersink,  Fig.  375,  is  also  used  with  the  drill- 
bow  ;  it  is  made  cylindrical,  and  pierced  for  the  reception  of  a 
small  central  pin — after  which  it  is  sharpened  to  a  chisel-edge,  as 
shown.  This  countersink  is  in  some  measure  a  diminutive  of  the 
pin  drills,  Figs.  382  to  385  ;  and  occasionally  circular  collars  are 
fitted  on  the  pin  for  its  temporary  enlargement,  or  around  the 
larger  part  to  serve  as  a  stop  and  limit  the  depth  to  which  the 
countersink  is  allowed  to  penetrate,  for  inlaying  the  heads  of 
screws.  The  pin  is  removed  when  the  instrument  is  sharpened. 

By  way  of  comparison  with  the  double-cutting  drills,  the  ordi- 


394 


THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 


nary  forms  of  those  which  only  cut  in  one  direction  are  shown  in 
Figs.  376,  377,  and  378.  Fig.  376  is  the  common  single  cutting 
drfll  for  the  drill-bow,  brace,  and  lathe.  The  point,  as  usual,  is 
nearly  a  rectangle,  but  is  formed  by  only  two  facets,  which  meet 
the  sides  at  about  80°  to  85°  ;  and  therefore  lie  very  nearly  in  con- 
tact with  the  extremity  of  the  hole  operated  upon,  thus  strictly 
agreeing  with  the  form  of  the  turning  tools  for  brass.  Fig.  377  is 
a°similar  drill,  particularly  suitable  for  horn,  tortoise-shell,  and 
substances  liable  to  agglutinate  and  clog  the  drill.  The  chamfers 
are  rather  more  acute,  and  are  continued  around  the  edge  behind 
its  largest  diameter,  so  that,  if  needful,  the  drill  may  also  cut  its 
way  out  of  the  hole. 

Fig.  378,  although  never  used  with  the  drill-bow,  nor  of  so  small 
a  size  as  in  the  wood-cut,  is  added  to  show  how  completely  the  drill 
proper  for  iron,  follows  the  character  of  the  turning  tools  for  that 
metal ;  the  flute  or  hollow  filed  behind  the  edge,  gives  the  hook- 
formed  acute  edge  required  in  this  tool,  which  is  in  other  respects 
like  Fig.  376 ;  the  form  proper  for  the  cutting  edge  is  shown  more 
distinctly  in  the  diagram  a,  Fig.  382. 


Figs.  376 


381. 


should  always  be  taken  to  have  a  proportional  degree  of 
strength  in  the  shafts  of  the  drills,  otherwise  they  tremble  and 
chatter  when  at  work  or  they  occasionally  twist  oft'  in  the  neck ; 
the  point  should  be  also  ground  exactly  central,  so  that  both 
edges  may  cut.  As  a  guide  for  the  proportional  thickness  of  the 
point,  it  may  measure  at  b,  Fig.  379,  the  base  of  the  cone,  about 
one-fifth  the  diameter  of  the  holer  and  at  p,  the  point,  about  one- 
eighth,  for  easier  penetration ;  but  the  fluted  drills  are  made  nearly 
of  the  same  thickness  at  the  point  and  base. 

In  all  the  drills  previously  described,  except  Fig.  374,  the  size 
of  the  point  is  lessened  each  time  of  sharpening ;  but  to  avoid  this 
loss  of  size,  a  small  part  is  often  made  parallel,  as  shown  in  Fig. 
379.  In  Fig.  380  this  mode  is  extended  by  making  the  drill  with 
a  cylindrical  lump,  so  as  to  fill  the  hole ;  this  is  called  the  re-centering 
drill  It  is  used  for  commencing  a  small  hole  in  a  flat-bottomed 
cylindrical  cavity ;  or  else,  in  rotation  with  the  common  piercing 
drill,  and  the  half-round  bit.  in  drilling  small  and  very  deep  holes 


DRILLS. 


395 


in  the  lathe.  Fig.  330  may  be  also  considered  to  resemble  the 
stop-drill,  upon  which  a  solid  lump  or  shoulder  is  formed,  or  a 
collar  is  temporarily  attached  by  a  side  screw,  for  limiting  the 
depth  to  which  the  tool  can  penetrate  the  work. 

Fig.  381,  the  cone  countersink,  may  be  viewed  as  a  multiplication 
of  the  common  single  cutting  drill.  Sometimes,  however,  the  tool 
is  filed  with  four  equi-distant  radial  furrows,  directly  upon  the 
axis,  and  with  several  intermediate  parallel  furrows  sweeping  at  an 
angle  around  the  cone.  This  makes  a  more  even  distribution  of 
the  teeth,  than  when  all  are  radial  as  in  the  figure,  and  it  is  always 
used  in  the  spherical  cutters,  or  countersinks,  known  as  cherries, 
which  are  used  in  making  bullet-moulds. 

On  comparison,  it  may  be  said  the  single  chamfered  drill,  Fig. 
376,  cuts  more  quickly  than  the  double  chamfered,  Fig.  370,  but 
that  the  former  is  also  more  disposed  of  the  two  to  swerve  or  run 
from  its  intended  position.  In  using  the  double  cutting  drills,  it 
is  also  necessary  to  drill  the  holes  at  once  to  their  full  sizes,  as 
otherwise  the  thin  edges  of  these  tools  stick  abruptly  into  the 
metal,  and  are  liable  to  produce  jagged  or  groovy  surfaces,  which 
destroy  the  circularity  of  the  holes ;  the  necessity  for  drilling  the 
entire  hole  at  once,  joined  to  the  feebleness  of  the  drill-bow,  limits 
the  size  of  these  drills. 

In  using  the  single  chamfered  drills,  it  is  customary,  and  on  sev- 
eral accounts  desirable,  to  make  large  holes  by  a  series  of  two  or 
more  drills ;  first  the  run  of  the  drill  is  in  a  measure  proportioned 
to  its  diameter,  therefore  the  small  tool  departs  less  from  its  in- 
tended path,  and  a  central  hole  once  obtained,  it  is  followed  with 
little  after-risk  by  the  single  cutting  drill,  which  is  less  penetra- 


Figs.  382 


383 


384 


385. 


tive.  This  mode  likewise  throws  out  of  action  the  less  favorable 
part  of  the  drill  near  the  point,  and  which  in  large  drills  is  neces- 
sarily thick  and  obtuse ;  the  subdivision  of  the  work  enables  a 
comparatively  small  power  to  be  used  for  drilling  large  holes,  and 
also  presents  the  choice  of  velocity  best  suited  to  each  progressive 
diameter  operated  upon.  But  where  sufficient  power  can  bo  ob- 


396  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

tained,  it  is  generally  more  judicious  to  enlarge  the  holes  previ- 
ously made  with  the  pointed  drills,  by  some  of  the  group  of  pin 
drills,  Figs.  382  to  385,  in  which  the  guide  principle  is  very  per- 
fectly employed :  they  present  a  close  analogy  to  the  plug  centre- 
bit,  and  the  expanding  centre-bit,  used  in  carpentry. 

The  ordinary  pin-drill,  Fig.  382,  is  employed  for  making  counter- 
sinks for  the  heads  of  screw-bolts  inlaid  flush  with  the  surface,  and 
also  for  enlarging  holes  commenced  with  pointed  drills,  by  a  cut 
parallel  with  the  surface;  the  pin-drill  is  also  particularly  suited 
to  thin  materials,  as  the  point  of  the  ordinary  drill  would  soon 
pierce  through,  and  leave  the  guidance  less  certain.  When  this 
tool  is  used  for  iron  it  is  fluted  as  usual,  and  a  represents  the  form 
of  the  one  edge  separately. 

Fig.  883  is  a  pin  drill  principally  used  for  cutting  out  large 
holes  in  cast-iron  and  other  plates.  In  this  case  the  narrow  cutter 
removes  a  ring  of  metal,  which  is  of  course  a  less  laborious  pro- 
cess than  cutting  the  whole  into  shavings.  When  this  drill  is 
applied  from  both  sides,  it  may  be  used  for  plates  half  an  inch  and 
upwards  in  thickness ;  as  should  not  the  tool  penetrate  the  whole 
of  the  way  through,  the  piece  may  be  broken  out,  and  the  rough 
edges  cleaned  with  a  file  or  a  broach. 

Fig.  384  is  a  tool  commonly  used  for  drilling  the  tube-plates  for 
receiving  the  tubes  of  locomotive  boilers  ;  the  material  is  about  f 
inch  thick,  and  the  holes  If  diameter.  The  loose  cutter  a,  is  fitted 
in  a  transverse  mortise,  and  secured  by  a  wedge  ;  it  admits  of  being 
several  times  ground,  before  the  notch  which  guides  the  blade 
for  centrality  is  obliterated.  Fig.  385  is  somewhat  similar  to  the 
last  two,  but  is  principally  intended  for  sinking  grooves ;  and  when 
the  tool  is  figured  as  shown  by  the  dotted  line,  it  may  be  used  for 
cutting  bosses  and  mouldings  on  parts  of  work  not  otherwise 
accessible. 

Many  ingenious  contrivances  have  been  made  to  insure  the 
dimensions  and  angles  of  tools  being  exactly  retained.  In  this 
class  may  be  placed  O'Tool's  pin  drill,  Figs.  386  and  387 ;  in  action 
it  resembles  the  fluted  pin  drill,  Fig.  382,  but  the  iron  stock  is 

Figs.  386  387. 


much  heavier,  and  is  attached  to  the  drilling  machine  by  the  square 
tang ;  the  stock  has  two  grooves  at  an  angle  of  about  10  degrees 
with  the  axis,  and  rather  deeper  behind  than  in  front.  Two  steel 
cutters,  or  nearly  parallel  blades  represented  black,  are  laid  in  the 
grooves;  they  are  fixed  by  the  ring  and  two  set  screws,  and 


DEILLS.  397 

are  advanced  as  they  become  worn  away,  by  two  adjusting  screws, 
a  «,  (one  only  seen),  placed  at  the  angle  of  10°  through  the  second 
ring ;  which,  for  the  convenience  of  construction,  is  screwed  upon 
the  drill  shaft  just  beyond  the  square  tang  whereby  it  is  attached 
to  the  drilling  machine.  The  cutters  are  ground  at  the  extreme 
ends,  but  they  also  require  an  occasional  touch  on  the  oilstone,  to 
restore  the  keenness  of  the  outer  angles,  which  become  somewhat 
rounded  by  the  friction.  The  diminution  from  the  trifling  ex- 
terior sharpening,  is  allowed  for  by  the  slightly  taper  form  of  the 
blades. 

The  process  of  drilling  generally  gives  rise  to  more  friction 
than  that  of  turning,  and  the  same  methods  of  lubrication  are 
used,  but  rather  more  commonly  and  plentifully  ;  thus  oil  is  used 
for  the  generality  of  metals,  or  from  economy,  soap  and  water; 
milk  is  the  most  proper  for  copper,  gold,  and  silver ;  and  cast-iron 
and  brass  are  usually  drilled  without  lubrication.  For  all  the 
above-named  metals  and  for  alloys  of  similar  degrees  of  hardness 
the  common  pointed  steel  drills  are  generally  used ;  but  for  lead 
and  very  soft  alloys,  the  carpenters'  spoon  bits,  and  nose  bits,  are 
usually  employed,  with  water. 

Having  considered  the  most  general  forms  of  the  cutting  parts 
of  drills,  we  will  proceed  to  explain  the  modes  in  which  they  are 
put  in  action  by  hand-power,  beginning  with  those  for  the  smallest 
diameters,  and  proceeding  gradually  to  the  largest. 

METHODS  OF  WORKING  DRILLS  BY  HAND- POWER. — The  smallest 
holes  are  those  required  in  watch- work,  and  the  general  form  of 
the  drill  is  shown  on  a  large  scale  in  Fig.  388 ;  it  is  made  of  a 
piece  of  steel  wire,  which  is  tapered  off'  at  the  one  end,  flattened  with 
the  hammer,  and  then  filled  up  in  the  form  shown  at  large  in  Fig. 
370 ;  lastly,  it  is  hardened  in  the  candle.  The  reverse  end  of  the 
instrument  is  made  into  a  conical  point,  and  is  also  hardened ;  near 
this  end  is  attached  a  little  brass  sheave  for  the  line  of  the  drill- 
bow,  which  in  watchmaking  is  sometimes  a  fine  horse-hair,  stretched 
by  a  piece  of  whalebone  of  about  the  size  of  a  goose's  quill 
stripped  of  its  feather 

•'    -       Fig.  388. 


The  watchmaker  holds  most  of  his  works  in  the  fingers,  both 
for  fear  of  crushing  them  with  the  table  vice,  and  also  that  he  may 
the  more  sensibly  feel  his  operations ;  drilling  is  likewise  performed 
by  him  in  the  same  manner.  Having  passed  the  bow-string  around 
the  pulley  in  a  single  loop  (or  with  a  round  turn},  the  centre  of  the 
drill  is  inserted  in  one  of  the  small  centre  holes  in  the  sides  of  the 
table  vice,  the  point  of  the  drill  is  placed  in  the  mark  or  cavity 
made  in  the  work  by  the  centre  punch ;  the  object  is  then  pressed 


398  THE   PRACTICAL   METAL-WOEKEB'S  ASSISTANT. 

forward  with  the  right  hand,  whilst  the  bow  is  moved  with  the 
left ;  the  Swiss  workmen  apply  the  hands  in  the  reverse  order,  as 
they  do  in  using  the  turn-bench. 

Clockmakers,  and  artisans  in  works  of  similar  scale,  fix  the  ob- 
ject in  the  tail-vice,  and  use  drills,  such  as  Fig.  388,  but  often 
larger  and  longer ;  they  are  pressed  forward  by  the  chest,  which  is 
defended  from  injury  by  the  breast-plate,  namely,  a  piece  of  wood 
or  metal  about  the  size  of  the  hand,  in  the  middle  of  which  is  a 
plate  of  steel,  with  centre'  holes  for  the  drill.  The  breast-plate  is 
sometimes  strapped  round  the  waist,  but  is  more  usually  supported 
with  the  left  hand,  the  fingers  of  which  are  ready  to  catch  the 
drill  should  it  accidentally  slip  out  of  the  centre. 

As  the  drill  gets  larger,  the  bow  is  proportionally  increased  in 
stiffness,  and  eventually  becomes  the  half  of  a  solid  cone,  about  1 
inch  in  diameter  at  the  larger  end,  and  30  inches  long ;  the  catgut 
string  is  sometimes  nearly  an  eighth  of  an  inch  in  diameter,  or  is 
replaced  by  a  leather  thong.  The  string  is  attached  to  the  smaller 
end  of  the  bow  by  a  loop  and  notch,  much  the  same  as  in  the 
archery  bow,  and  is  passed  through  a  hole  at  the  larger  end,  and 
made  fast  with  a  knot ;  the  surplus  length  is  wound  round  the 
cane,  and  the  cord  finally  passes  through  a  notch  at  the  end,  which 
prevents  it  from  uncoiling. 

Steel  bows  are  also  occasionally  used ;  these  are  made  something 
like  a  fencing  foil,  but  with  a  hook  at  the  end  for  the  knot  or  loop 
of  the  cord,  and  with  a  ferrule  or  a  ratchet,  around  which  the  spare 
cord  is  wound.  Some  variations  also  are  made  in  the  sheaves  of 
the  large  drills ;  sometimes  they  are  cylindrical,  with  a  fillet  at 
each  end ;  this  is  desirable,  as  the  cord  necessarily  lies  on  the 
sheave  at  an  angle,  in  fact  in  the  path  of  a  screw ;  it  pursues  that 
path,  and  with  the  reciprocation  of  the  drill-bow,  the  cord  trav- 
erses, or  screws  backwards  and  forwards  upon  the  sheave,  but  is 
prevented  from  sliding  off  by  the  fillet.  Occasionally,  indeed, 
the  cylindrical  sheave  is  cut  with  a  screw  coarse  enough  to  receive 
••the  cord,  which  may  then  make  three  or  four  coils  for  increased 
purchase,  and  have  its  natural  screw-like  run  without  any  fretting 
whatever ;  but  this  is  only  desirable  when  the  holes  are  large,  and 
the  drill  is  almost  constantly  used,  as  it  is  tedious  to  wind  on  the 
cord  for  each  individual  hole.  The  structure  of  the  bows,  breast- 
plates, and  pulleys,  although  often  varied,  is  sufficiently  familiar  to 
be  understood  without  figures. 

When  the  shaft  of  the  drill  is  moderately  long,  the  workman 
can  readily  observe  if  the  drill  is  square  with  the  work  as  regards 
the  horizontal  plane ;  and  to  remove  the  necessity  for  the  observa- 
tion of  an  assistant  as  to  the  vertical  plane,  a  trifling  weight  is 
sometimes  suspended  from  the  drill  shaft  by  a  metal  ring  or  hook ; 
the  joggling  motion  shifts  the  weight  to  the  lower  extremity ;  the 
tool  is  only  horizontal  when  the  weight  remains  central. 

In  many  cases,  the  necessity  for  repeating  the  shaft  and  pulley 
of  the  drill  is  avoided  by  the  employment  of  holders  of  various 


DRILLS. 


399 


kinds,  or  drill-stocks,  which  serve  to  carry  any  required  number  of 
drill  points.  The  most  simple  of  the  drill-stocks  is  shown  in  Fig. 
389 ;  it  has  the  centre  and  pulley  of  the  ordinary  drill,  but  the  op- 


Figs.  389 


posite  end  is  pierced  with  a  nearly  cylindrical  hole,  just  at  the 
inner  extremity  of  which  a  diametrical  notch  is  filed.  The  drill  is 
shown  separately  at  a ;  its  shank  is  made  cylindrical,  or  exactly  to 
fit  the  hole,  and  a  short  portion  is  nicked  down  also  to  the  diamet- 
rical line  so  as  to  slide  into  the  gap  in  the  drill-stock,  by  which 
the  drill  is  prevented  from  revolving :  the  end  serves  also  as  an 
abutment,  whereby  it  may  be  thrust  out  with  a  lever.  Sometimes 
a  diametrical  transverse  mortise,  narrower  than  the  hole,  is  made 
through  the  drill-stock,  and  the  drill  is  nicked  in  on  both  sides; 
and  the  designer,  Mr.  R.  Balfe,  of  Kilkenny,  proposes  that  the 
cylindrical  hole  of  389  should  be  continued  to  the  bottom  of  the 
notch,  that  the  end  of  the  drill  should  be  filed  off  obliquely,  and 
that  it  should  be  prevented  from  rotating  by  a  pin  inserted  through 
the  cylindrical  hole  parallel  with  the  notch ;  the  taper  end  of  the 
drill  would  then  wedge  fast  beneath  the  pin. 

Drills  are  also  frequently  used  in  the  drilling-lathe;  this  is  a 
miniature  lathe-head,  the  frame  of  which  is  fixed  in  the  table  vice ; 
the  mandrel  is  pierced  for  the  drills,  and  has  a  pulley  for  the  bow, 
therein  resembling  Fig.  390,  except  that  it  is  used  as  a  fixture. 

The  figure  390,  just  referred  to,  represents  one  variety  of  another 
common  form  of  the  drill-stock,  in  which  the  revolving  spindle  is 
fitted  in  a  handle,  so  that  it  may  be  held  in  any  position  without 
the  necessity  for  the  breast-plate ;  the  handle  is  hollowed  out  to 
serve  for  containing  the  drills,  and  is  fluted  to  assist  the  grasp. 


Figs. 
391 1 


392 — < 


393.  — 


400  THE   PRACTICAL   METAL-WOEKER's  ASSISTANT. 

Fig.  391  represents  the  socket  of  an  "universal  drill-stock,'1'1  in- 
vented by  James  O'Kyan :  it  is  pierced  with  a  hole  as  large  as  the 
largest  of  the  wires  of  which  the  drills  are  formed,  and  the  hole 
terminates  in  an  acute  hollow  cone.  The  end  of  the  drill-stock  is 
tapped  with  two  holes,  placed  on  a  diameter;  the  one  screw,  a,  is  of 
a  very  fine  thread,  and  has  at  the  end  two  shallow  diametrical 
notches;  the  other,  b,  is  of  a  coarser  thread,  and  quite  flat  at  the 
extremity.  The  wire-drill  is  placed  against  the  bottom  of  the  hole, 
and  allowed  to  lean  against  the  adjusting-screw  a,  and  if  the  drill 
be  not  central,  this  screw  is  moved  one  or  several  quarter-turns, 
until  it  is  adjusted  for  centrality ;  after  which  the  tool  is  strongly 
fixed  by  the  plain  set-screw  5. 

Fig.  392  is  a  drill-stock  contrived  by  Mr.  Murphy.  It  consists 
of  a  tube,  the  one  end  of  which  has  a  fixed  centre  and  pulley, 
much  the  same  as  usual.  The  opposite  end  of  the  tube  has  a  piece 
of  steel  fixed  into  it  which  is  first  drilled  with  a  central  hole,  and 
then  turned  as  a  conical  screw,  to  which  is  fitted  a  corresponding 
screw  nut,  n ;  the  socket  is  then  sawn  down  with  two  diametrical 
notches,  to  make  four  internal  angles  ;  and  lastly,  the  socket  is 
hardened.  When  the  four  sections  are  compressed  by  the  nut, 
their  edges  stick  into  the  drill  and  retain  it  fast,  and,  provided  the 
instrument  is  itself  concentric,  and  the  four  parts  are  of  equal 
strength,  the  centrality  of  the  drill  is  at  once  insured.  The  out- 
side of  the  nut,  and  the  square  hole  in  the  key  k,  are  each 
taper,  for  more  ready  application ;  and  the  drills  are  of  the  most 
simple  kind,  namely,  lengths  of  wire  pointed  at  each  end,  as  in 
Fig.  393. 

The  sketch,  Fig.  392,  is  also  intended  to  explain  another  useful 
application  of  this  drill-stock  as  an  upright  or.  pump-drill,  well 
known  among  the  ancient  Irish  as  the  breast-drill.  Occasionally 
the  pump-drill  and  the  common  drill-stock  are  mounted  in  frames, 
by  which  their  paths  are  more  exactly  defined ;  but  these  con- 
trivances are  far  from  being  generally  required,  and  enough  will 
be  said  in  reference  to  the  use  of  revolving  braces,  to  lead  to  such 
applications,  if  considered  requisite,  for  reciprocating  drills. 

Holes  that  are  too  large  to  be  drilled  solely  by  the  breast-drill 
and  drill-bow,  are  frequently  commenced  with  those  useful  instru- 
ments, and  are  then  enlarged  by  means  of  the  hand-brace,  which 
is  very  similar  to  that  used  in  carpentry,  except  that  it  is  more 
commonly  made  of  iron  instead  of  wood,  is  somewhat  larger,  and 
generally  made  without  the  spring-catch. 

Holes  may  be  extended  to  about  half  an  inch  diameter  with 
the  hand-brace  ;  but  it  is  much  more  expeditious  to  employ  still 
larger  and  stronger  braces,  and  to  press  them  into  the  work  in 
various  ways  by  weights,  levers,  and  screws,  instead  of  by  the 
muscular  effort  alone. 

Fig.  394  represents  the  old  smith's  press-drill,  which  although 
cumbrous  and  much  less  used  than  formerly,  is  nevertheless  simple 
and  effective.    It  consists  of  two  pairs  of  wooden  standards,  be 
I 


DRILLS. 


401 


tween  which  works  the  beam  a  b,  the  pin  near  a  is  placed  at  any 
height,  but  the  weight  w  is  not  usually  changed,  as  the  greater  or 

395. 


Figs.  394 


less  pressure  for  large  and  small  drills  is  obtained  by  placing  the 
brace  more  or  less  near  to  the  fulcrum  a ;  and  this  part  of  the  beam 
is  shod  with  an  iron  plate  full  of  small  centre  holes  for  the  brace. 
The  weight  is  raised  by  the  second  lever  c  d,  the  two  being  united 
by  a  chain,  and  a  light  chain  or  rope  is  also  suspended  from  d, 
to  be  within  reach  of  the  one  or  two  men  engaged  in  moving 
the  brace.  It  is  necessary  to  relieve  the  weight  when  the  drill 
is  nearly  through  the  hole,  otherwise  it  might  suddenly  break 
through,  and  the  drill  becoming  fixed,  might  be  twisted  off  in 
the  neck. 

The  inconveniences  in  this  machine  are,  that  the  upper  point  of 
the  brace  moves  in  an  arc  instead  of  a  right  line ;  the  limited  path 
when  strong  pressures  are  used,  which  makes  it  necessary  to  shift 
the  fulcrum  a ;  and  also  the  necessity  for*  re-adjusting  the  work 
under  the  drill  for  each  different  hole,  which  in  awkwardly -shaped 
pieces  is  often  troublesome. 

A  portable  contrivance,  of  similar  date,  is  an  iron  bow  frame  or 
clamp,  shown  in  Fig.  395.  The  pressure  is  applied  by  a  screw, 
but  in  almost  all  cases,  whilst  the  one  individual  drills  the  hole, 
the  assistance  of  another  is  required  ,to  hold  the  frame  ;  395  only 
applies  to  comparatively  thin  parallel  works,  and  does  not  present 
the  necessary  choice  of  position.  Another  tool  of  this  kind,  used 
for  boring  the  side  holes  in  cast-iron  pipes  for  water  and  gas,  ia 
doubtless  familiarly  known ;  the  cramp  or  frame  divides  into  two 
branches  about  two  feet  apart,  and  these  terminate  like  hooks, 
which  loosely  embrace  the  pipe,  so  that  the  tool  retains  its  position 
without  constraint,  and  it  may  be  used  with  great  facility  by  one 
individual. 

Fig.  396  will  serve  to  show  the  general  character  of  various  con^ 
structions  of  more  modern  apparatus,  to  be  used  for  supplying  the 
pressure  in  drilling  holes  with  hand  braces.  It  consists  of  a  cylin- 
drical bar  a,  upon  which  the  horizontal  rectangular  rod  b  is  fitted 
with  a  socket,  so  that  it  may  be  fixed  at  any  height,  or  in  any 
angular  position,  by  the  set-screw  c.  Upon  b  slides  a  socket,  which 
26 


402 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


Fig.  396. 


is  fixed  at  all  distances  from  a  by  its 
set-screw  d ;  and  lastly,  this  socket  has 
a  long  vertical  screw  e,  by  which  the 
brace  is  thrust  into  the  work. 

The  object  to  be  drilled  having  been 
placed  level,  either  upon  the  ground, 
on  trestles,  on  the  work  bench,  or  in 
the  vice,  according  to  circumstances, 
the  screws  c  and  d  are  loosened,  and 
the  brace  is  put  in  position  for  work. 
The  perpendicularity  of  the  brace  is 
then  examined  with  a  plumb-line,  ap- 
plied in  two  positions  (the  eye  being 
first  directed  as  it  were  along  the 
north  and  south  line,  and  then  along 
the  east  and  west),  after  which  the 
whole  is  made  fast  by  the  screws  c 
and  d.  The  one  hole  having  beea 
drilled,  the  socket  and  screws  present 
great  facility  in  re-adjusting  the  in- 
strument for  subsequent  holes  without 
the  necessity  for  shifting  the  work,  which  would  generally  be 
attended  with  more  trouble  than  altering  the  drill-frame  by  its 
screws. 

Sometimes  the  rod  a  is  rectangular,  and  extends  from  the  floor 
to  the  ceiling ;  it  then  traverses  in  fixed  sockets,  the  lower  of  which 
has  a  set  screw  for  retaining  any  required  position.  In  the  tool 
represented,  the  rod  a.  terminates  in  a  cast-iron  base,  by  which  it 
may  be  grasped  in  the  tail- vice,  or  when  required  it  may  be  fixed 
upon  the  bench ;  in  this  case  the  nut  a  is  unscrewed,  the  cast-iron 
plate,  when  reversed  and  placed  on  the  bench,  serves  as  a  pedestal, 
the  stem  is  passed  through  a  hole  in  the  bench,  and  the  nut  and 
washer,  when  screwed  on  the  stem  beneath,  secure  all  very  strongly 
together.  _  Even  in  establishments  where  the  most  complete  drill- 
ing machines  driven  by  power  are  at  hand,  modifications  of  the 
press  drill  are  among  the  indispensable  tools :  many  are  contrived 
with  screws  and  clamps,  by  which  they  are  attached  directly  to 
such  works  as  are  sufficiently  large  and  massive  to  serve  as  a 
foundation. 

Various  useful  drilling  tools  for  engineering  works  are  fitted 
with  left  hand  screws,  the  unwinding  of  which  elongate  the  tools  ; 
so  that  for  these  instruments  which  supply  their  own  pressure,  it  is 
only  necessary  to  find  a  solid  support  for  the  centre  They  apply 
very  readily  in  drilling  holes  within  boxes  and  panels,  and  the 
abutment  is  often  similarly  provided  by  projecting  parts  of  the 
castings  ;  or  otherwise  the  fixed  support  is  derived  from  the  wall 
or  ceiling,  by  aid  of  props  arranged  in  the  most  convenient  manner 
that  presents  itself. 
•Fig.  .397  is  the  common  brace,  which  only  differs  from  that  in 


DRILLS. 


403 


Fig.  396  in  the  left  hand  screw ;  a  right  hand  screw  would  be  un- 
wound in  the  act  of  drilling  a  hole  when  the  brace  is  moved  round 
in  the  usual  direction,  which  agrees  with  the  path  of  a  left  hand 
screw.  The  cutting  motion  produces  no  change  in  the  length  of 
the  instrument,  and  the  screw  being  held  at  rest  for  a  moment 
during  the  revolution,  sets  in  the  cut ;  but  towards  the  last,  the 
feed  is  discontinued,  as  the  elasticity  of  the  brace  and  work  suffice 
for  the  reduced  pressure  required  when  the  drill  is  nearly  through, 
and  sometimes  the  screw  is  unwound  still  more  to  reduce  it. 

The  lever-drill,  Fig.  398,  differs  from  the  latter  figure  in  many 
respects  ;  it  is  much  stronger,  and  applicable  to  larger  holes ;  the 
drill  socket  is  sufficiently  long  to  be  cut  into  the  left  hand  screw, 
and  the  piece  serving  as  the  screwed  nut,  is  a  loop  terminating  in 
the  centre  point.  The  increased  length  of  the  lever  gives  much 
greater  purchase  than  in  the  crank-formed  brace,  and  in  addition 
the  lever-brace  may  be  applied  close  against  a  surface  where  the 
crank-brace  cannot  be  turned  round ;  in  this  case  the  lever  is  only 
moved  a  half  circle  at  a  time,  and  is  then  slid  through  for  a  new 
purchase,  or  sometimes  a  spanner  or  wrench  is  applied  directly 
upon  the  square  drill  socket. 


Figs.  397 


The  same  end  is  more  conveniently  fulfilled  by  the  ratchet-drill, 
Fig.  399,  apparently  derived  from  the  last :  it  is  made  by  cutting 
ratchet  teeth  in  the  drill  shaft,  or  putting  on  the  rachet  as  a  sepa- 
rate piece,  and  fixing  a  pall  or  detent  to  the  handle ;  the  latter  may 
then  be  moved  backward  to  gather  up  the  teeth,  and  forward  to 
thrust  round  the  tool,  with  less  delay  than  the  lever  in  Fig.  398, 
and  with  the  same  power,  the  two  being  of  equal  length.  This 
tool  is  also  peculiarly  applicable  to  reaching  into  angles  and  places 
in  which  neither  the  crank-form  brace,  nor  the  lever-drill  will 
apply.  Fig.  400,  the  ratchet-  lever,  in  part  resembles  the  ratchet- 
drill,  but  the  pressure-screw* of  the  latter  instrument  must  be 


404  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

sought  in  some  of  the  other  contrivances  referred  to,  as  the  rat- 
chet-lever has  simply  a  square  aperture  to  fit  on  the  tang  of  the 
drill  d,  which  latter  must  be  pressed  forward  by  some  independent 
means. 

Fig.  401,  which  is  a  simple  but  necessary  addition  to  the  braces 
and  drill  tools,  is  a  socket  having  at  one  end  a  square  hole  to  re- 
ceive the  drills,  and  at  the  opposite,  a  square  tang  to  fit  the  brace ; 
by  this  contrivance  the  length  of  the  drill  can  be  temporarily  ex- 
tended for  reaching  deeply  seated  holes.  The  sockets  are  made 
of  various  lengths,  and  sometimes  two  or  three  are  used  together, 
to  extend  the  length  of  the  brace  to  suit  the  position  of  the  prop  ; 
but  it  must  be  remembered  that,  with  the  additional  length,  the 
torsion  becomes  much  increased,  and  the  resistance  to  end-long 
pressure  much  diminished,  therefore  the  sockets  should  have  a  bulk 
proportionate  to  their  length. 

The  French  brace  is  also  constructed  in  iron,  with  a  pair  of 
equal  bevel  pinions,  and  a  left  hand  centre  screw,  like  the  tools 
Figs.  397,  398,  and  399  ;  it  is  then  called  the  corner-drill  Some- 
times also,  as  in  Figs.  402  and  403,  the  bevel  wheels  are  made  with 
a  hollow  square  or  axis,  as  in  the  ratchet-lever,  Fig.  400 ;  the 
driver  then  hangs  loosely  on  the  square  shank  of  the  drill  tool,  or 
cutter  bar,  and  when  the  pinion  on  the  handle  is  only  one-third  or 
fourth  of  the  size  of  the  bevel  wheel  with  the  square  hole,  it  is  an 
effective  driver  for  various  uses ;  the  long  tail  or  lever  serves  to 
prevent  the  rotation  of  the  driver,  by  resting  against  some  part  of 
the  work  or  of  the  work-bench. 

Fig.  402 


Fig.  403. 


All  the  before -mentioned  tools  are  commonly  found  in  a  variety 
of  shapes  in  the  hands  of  the  engineer,  but  it  will  be  observed  they 
are  all  driven  by  hand  power,  and  are  carried  to  the  work.  I  shall 
conclude  this  section  with  the  description  of  a  more  recent  drill 
tool  of  the  same  kind,  invented  by  Mr.  O'Kelly  of  Dublin. 


DRILLS. 


405 


This  instrument  is -represented  of  one-eighth  size,  in  the  side 
view,  Fi°r.  404,  in  the  front  view,  405,  and  in  the  section,  406 ;  it  is 
about  twice  as  powerful  as  Fig.  403,  and  has  the  advantage  of  feed- 
ing the  cut  by  a  differential  motion.  The  tangent  screw  moves  at 
the  same  time  the  two  worm  wheels  a  and  b ;  the  former  has  15 
teeth,  and  serves  to  revolve  the  drill;  the  latter  has  16  teeth,  and 
by  the  difference  between  the  two,  or  the  odd  tooth,  advances  the 
drill  slowly  and  continually,  which  may  be  thus  explained. 

The  lower  wheel  a,  of  15  teeth,  is  fixed  on  the  drill  shaft,  and 
this  is  tapped  to  receive  the  centre  screw  c,  of  four  threads-  per 
inch.  The  upper  wheel  of  16  teeth  is  at  the  end  of  a  socket  d. 
(which  is  represented  black  in  the  section  Fig.  406),  and  is  con-' 
nected  with  the  centre  screw  c,  by  a  collar  and  internal  key,  which 
last  fits  a  longitudinal  groove  cut  up  the  side  of  the  screw  c;  now, 
therefore,  the  internal  and  external  screws  travel  constantly  round, 
and  nearly  at  the  same  rate,  the  difference  of  one  tooth  in  the 
wheels  serving  continually  and  slowly  to  project  the  screw  c,  for 
feeding  the  cut.  To  shorten  or  lengthen  the  instrument  rapidly, 
the  side  screw  e  is  loosened ;  this  sets  the  collar  and  key  free  from 
the  16  wheel,  and  the  centre  screw  may  for  the  time  be  moved  in- 
dependently by  a  spanner. 


Figs.  404 


405 


406. 


The  differential  screw-drill,  having  a  double  thread  in  the  large 
worm,  shown  detached  at/,  requires  7£  turns  of  the  handle  to -move 
the  drill  once  round,  and  the  feed  is  one  64th  of  an  inch  for  each 
turn  of  the  drill ;  that  being  the  sum  of  16  by  4. 

DRILLING  AND  BORING  MACHINES. — The  motion  of  the  lathe 
mandrel  is  particularly  proper  for  giving  action  to  the  various 
single-cutting  drills  referred  to ;  they  are  then  fixed  in  square  or 
round  hole  drill-chucks  which  screw  upon  the  lathe  mandrel. 
The  motion  of  the  lathe  is  more  uniform  than  that  of  the  hand 
tools,  and  the  popit-head,  with  its  flat  boring  flange  and  pressure 
screw,  forms  a  most  convenient  arrangement,  as  the  works  are  then 
carried  to  the  drill  exactly  at  right  angles  to  the  face.  But  in 
drilling  very  small  holes  in  the  lathe,  there  is  some  risk  of  uncon- 
sciously employing  a  greater  pressure  with  the  screw  than  the 


406  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

slender  drills  will  bear.  Sometimes  the  cylinder  is  pressed  for  ward 
by  a  horizontal  lever  fixed  on  a  fulcrum ;  at  other  times  the  cylin- 
der is  pressed  forward  by  a  spring,  by  a  rack  and  pinion  motion, 
or  by  a  simple  lever,  and  the  best  arrangement  of  this  latter  kind 
is  that  next  to  be  described. 

In  the  manufacture  of  harps  there  is  a  vast  quantity  of  small 
drilling,  and  the  pressure  of  the  cylinder  popit-head  is  given  by 
means  of  a  long,  straight,  double  ended  lever,  which  moves  hori- 
zontally (at  about  one-third  from  the  back  extremity),  upon  a 
fixed  post  or  fulcrum  erected  upon  the  back-board  of  the  lathe. 
The  front  of  the  lever  is  connected  with  the  sliding  cylinder  by  a 
link  or  connecting  rod,  and  the  back  of  the  lever  is  pulled  towards 
the  right  extremity  of  the  lathe,  by  a  cord  which  passes  over  a 
pulley  at  the  edge  of  the  back-board,  and  then  supports  a  weight 
of  about  twenty  pounds. 

Both  the  weight  and  connecting  rod  may  be  attached  at  various 
distances  from  the  fixed  fulcrum  between  them.  When  they  are 
fixed  at  equal  distances  from  the  axis  of  the  lever,  the  weight,  if 
twenty  pounds,  presses  forward  the  drill  with  twenty  pounds,  less 
a  little  friction ;  if  the  weight  be  two  inches  from  the  fulcrum  and 
the  connecting  rod  eight  inches,  the  effect  of  the  weight  is  reduced 
to  five  pounds ;  if,  on  the  other  hand,  the  weight  be  at  eight  and 
the  connecting  rod  at  two  inches,  the  pressure  is  fourfold,  or  eighty 
pounds. 

The  connecting  rod  is  full  of  holes,  so  that  the  lever  may  be  ad- 
justed exactly  to  reach  the  body  of  the  workman,  who  standing 
with  his  face  to  the  mandrel,  moves  the  lever  with  his  back,  and 
has  therefore  both  hands  at  liberty  for  managing  the  work.  Some- 
times a  stop  is  fixed  on  the  cylinder,  for  drilling  holes  to  one  fixed 
depth ;  gages  are  attached  to  the  flange,  for  drilling  numbers  of 
similar  pieces  at  any  fixed  distance  from  the  edge :  in  fact,  this  very 
useful  apparatus  admits  of  many  little  additions  to  facilitate  the  use 
of  drills  and  revolving  cutters. 

Great  numbers  of  circular  objects,  such  as  wheels  and  pulleys, 
are  chucked  to  revolve  truly  upon  the  lathe  mandrel,  whilst  a  sta- 
tionary drill  is  thrust  forward  against  them,  by  which  means  the 
concentricity  between  the  hole  and  the  edge  is  insuned. 

The  drills  employed  for  boring  works  chucked  on  the  lathe,  have 
mostly  long  shafts,  some  parts  of  which  are  rectangular  or  parallel, 
so  that  they  may  be  prevented  from  revolving  by  a  hook  wrench,  a 
spanner  or  a  hand- vice,  applied  as  a  radius,  <pr  by  other  means. 
The  ends  of  the  drill  shafts  are  pierced  with  small  centre  holes,  in 
order  that  they  may  be  thrust  forward  by  the  screw  of  the  popit- 
head,  either  by  hand  or  by  self-acting  motion :  namely,  a  connection 
between  either  the  mandrel-  or  the  prime  mover  of  the  lathe,  and 
the^  screw  of  the  popit-head,  by  cords  and  pulleys,  by  wheels  and 
pinions,  or  other  contrivances. 

The  drills,  Figs.  376  and  378,  p.  394,  are  used  for  boring  ordinary 
holes :  but  for  those  requiring  greater  accuracy,  or  a  more  exact 


DRILLS. 


407 


repetition  of  the  same  diameter,  the  lathe  drills,  Figs.  407  to  409 
are  commonly  selected.  Fig.  407,  which  is  drawn  in  three  views 
and  to  "the  same  scale  as  the  former  examples,  is  called  the  half- 
round  bit,  or  the  cylinder  bit.  The  extremity  is  ground  a  little  in- 
clined to  the  right  angle,  both  horizontally  and  vertically,  to  about 
the  extent  of  three  to  five  degrees.  It  is  necessary  to  turn  out  a 
shallow  recess  exactly  to  the  diameter  of  the  end  of  the  bit  as  a 
commencement ;  the  circular  part 'of  the  bit  fills  the  hole,  and  is 
thereby  retained  central,  whilst  the  left  angle  removes  the  shaving. 
This  tool  should  never  be  sharpened  on  its  diametrical  face,  or  it 
would  soon  cease  to  deserve  its  appellation  of  half-round  bit :  some 
indeed  give  it  about  one-thirtieth  more  of  the  circumference.  It  is 
generally  made  very  slightly  smaller  behind,  to  lessen  the  friction ; 
and  the  angle,  not  intended  to  cut,  is  a  little  blunted  half-way  round 
the  curve,  that  it  may  not  scratch  the  hole  from  the  pressure  of  the 
cutting  edge.  It  is  lubricated  with  oil  for  the  metals  generally, 
but  is  used  dry  for  hard  woods  and  ivory,  and  sometimes  for  brass. 
The  rose-bit,  Fig.  408,  is  also  very  much  used  for  light  finishing 
cuts,  in  brass,  iron,  and  steel ;  the  extremity  is  cylindrical,  or  in  the 
smallest  degree  less  behind,  and  the  end  is  cut  into  teeth  like  a 
countersink ;  the  rose-bit,  when  it  has  plenty  of  oil,  and  but  very 
little  to  remove,  will  be  found  to  act  beautifully,  but  this  tool  is 
less  fit  for  cast-iron  than  the  bit  next  to  be  described.  The  rose-bit 
may  be  used  without  oil  for  the  hard  woods  and  ivory,  in  which 
it  makes  a  very  clean  hole;  but  as  the  end  of  the  tool  is  chamfered, 
it  does  not  leave  a  flat-bottomed  recess  the  same  as  the  half-round 
bit,  and  is  therefore  only  used  for  thoroughfare  holes. 


Figs.  407 


408 


409 


410 


1 



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>.  -•* 

|  

411. 


The  drill,  Fig.  409,  is  much  employed,  but  especially  fcfr  cast- 
iron  work  ;  the  end  of  the  blade  is  made  very  nearly  parallel,  the 
two  front  corners  are  ground  slightly  rounding,  and  are  chamfered, 
the  chamfer  is  continued  at  a  reduced  angle  along  the  two  sides,  to 
the  extent  of  about  two  diameters  in  length :  this  portion  is  not 


408  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

strictly  parallel,  but  is  very  slightly  largest  in  the  middle  or  barrel- 
shaped  :  this  drill  is  used  dry  for  cast-iron. 

Fig.  409,  in  common  with  all  drills  that  cut  on  the  side,  tiiay,  by 
improper  direction,  cut  sideways,  making  the  hole  above  the  in- 
tended diameter ;  but  when  the  hole  has  been  roughly  bored  with  a 
common  fluted  drill,  the  end  of  the  latter  is  used  as  a  turning  tool, 
to  make  an  accurate  chamfer,  the  bit  409  is  then  placed  through 
the  stay,  as  shown  in  Fig.  410,  and  is  lightly  supported  between 
the  chamfer  upon  the  work  and  the  centre  of  the  popit-head ;  the 
moment  any  pressure  comes  on  the  drill,  its  opposite  edges  stick 
into  the  inner  sides  of  the  loop  (as  more  clearly  explained  in  Fig. 
411),  which  thus  restrains  its  position;  much  the  same  as  the  point 
and  edges  of  the  turning  tools  for  iron  dig  into  the  rest,  and  secure 
the  position  of  those  tools. 

It  is  requisite  the  drill  and  loop  should  be  exactly  central ;  Fig. 
410  shows  the  common  form  of  the  stay  when  fitted  to  the  lathe 
rest,  but  it  is  sometimes  made  as  a  swing  gate,  to  turn  aside,  whilst 
the  piece  which  has  been  drilled  "Is  removed,  and  the  next  piece  to 
be  operated  upon  is  fixed  in  the  lathe.  Sometimes  also  the  drill 

409  has  blocks  of  hardwood  attached  above  and  below  it,  to  com- 
plete the  circle ;  this  is  usual  for  wrought-iron  and  steel,  and  oil  is 
then  employed. 

These  three  varieties  are  exclusively  lathe-drills,  and  are  in- 
tended for  the  exact  repetition  of  a  number  of  holes  of  the  par- 
ticular sizes  of  the  bits,  and  which,  on  that  account,  should  remove 
only  a  thin  shaving  to  save  the  tools  from  wear. 

The  cylinder  bits,  however,  may  be  used  for  enlarging  holes 
below  half  an  inch,  to  the  extent  of  about  one-third  their  diameter 
at  one  cut ;  and  for  holes  from  half  an  inch  to  one  inch,  about 
one-fourth  their  diameter  or  less,  and  as  the  bits  increase  in  size, 
the  proportion  of  the  cut  to  the  diameter  should  decrease. 

The  cylinder  bit  is  not  intended  to  be  used  for  drilling  holes  in 
the  solid  material,  and  as  the  piercing  drills  are  apt  to  swerve  in 
drilling  small  and  very  deep  holes,  the  following  rotation  in  the 
tools  is  sometimes  resorted  to.  A  drill,  Fig.  376,  p.  394,  say  three- 
sixteenths  diameter,  is  first  sent  into  the  depth  of  an  inch  or  up- 
wards, and  the  hole  is  enlarged  by  a  cylinder*  bit  of  one-quarter 
inch  diameter.  The  centre  at  the  end  of  the  hole  is  then  restored 
to  exact  truth,  by  Fig.  380,  a  re-centering  drill,  the  plug  of  which 
exactly  fits  the  hole  made  by  the  cylinder  bit ;  the  extremity  of 
the  re-centering  drill  then  acts  as  a  fixed  turning  tool,  and  should 
the  first  drill  have  run  out  of  its  position,  Fig.  380  corrects  the 
centre  at  the  end  of  the  hole.  Another  short  portion  is  then 
drilled  with  Fig.  376,  enlarged  with  the  half-round  bit,  and  the 
conical  extremity  is  again  corrected  with  the  re-centering  drill ; 
the  three  tools  are  thus  used  in  rotation  until  the  hole  is  completed, 
and  which  may  be  then  cleaned  out  with  one  continued  cut,  made 
with  a  half-round  bit  a  little  larger  than  that  previously  used. 

Some  of  the  large  half-round  bits  are  so  made  that  the  one  stock 


DRILLS. 


403 


will  serve  for  several  cutters  of  different  diameters.  In  the  bit3 
used  for  boring  out  ordnance,  the  parallel  shaft  of  the  boring  bar 
slides  accurately  in  a  groove,  exactly  parallel  with  the  bore  of  the 
gun ;  the  cutting  blade  isya  small  piece  of  steel  affixed  to  the  end 
of  the  half-round  block,  which  is  either  entirely  of  iron,  or  partly 
of  wood ;  and  the  cut  is  advanced  by  a  rack  and  pinion  move- 
ment, actuated  either  by  the  descent  of  a  constant  weight,  or  by  a 
self-acting  motion  derived  from  the  prime  mover.  For  making 
the  spherical,  parabolical  or  other  termination  to  the  bore,  cutters 
of  corresponding  forms  are  fixed  to  the  bar. 

The  outside  of  the  gun  is  usually  turned,  whilst  the  boring  is 
going  on,  by  hand  tools.  A  plug  of  copper  is  screwed  into  the 
brass  guns  to  be  perforated  for  the  touch-hole,  copper  being  less 
injured  by  repeated  discharges,  than  the  alloy  of  nine  parts  copper 
and  one  part  tin,  used  for  the  general  substance  of  the  gun ;  the 
curved  bit  smooths  off  the  end  of  the  plug. 

There  are  very  many  works  which  from  their  weight  or  size, 
cannot  be  drilled  in  the  lathe  in  its  ordinary  position,  as  it  is 
scarcely  possible  to  support  them  steadily  against  the  drill ;  but 
these  works  are  readily  pierced  in  the  drilling  machine,  which  may 
be  viewed  as  a  lathe  with  a  vertical  mandrel,  and  with  the  flange 
of  the  popit-head,  enlarged  into  a  table  for  the  work,  which  then 
lies  in  the  horizontal  position  simply  by  gravity,  or  is  occasionally 
fixed  on  the  table  by  screws  and  clamps.  The  structure  of  these 
important  machines  admits  of  almost  endless  diversity,  and  in 
nearly  every  manufactory  some  peculiarity  of  construction  may  be 
observed. 

Figs.  412  and  413,  exhibit  a  "Portable  Hand-drill,"  which  is 
introduced  as  a  simple  and  efficient  example,  that -may  serve  to 

Figs.  412 


convey  the  general  characters  of  the  drilling  machines.  The 
spindle  is  driven  by  a  pair  of  bevel  pinions,  the  one  is  attached  to 
the  axis  of  the  vertical  fly-wheel,  the  other  to  the  drill  shaft,  which 
is  depressed  by  a  screw  moved  by  a  small  hand-wheel.  , 

Sometimes,  as  in  the  lathe,  the 'drilling  spindle  revolves  without 


410  THE   PRACTICAL   METAL-WOBKEB's  ASSISTANT. 

endlong  motion,  and  the  table  is  raised  by  a  treadle  or  by  a  hand 
lever  ;  but  more  generally  the  drill-shaft  is  cylindrical  and  revolves 
in,  and  also  slides  through  fixed  cylindrical  bearings.  The  drill 
spindle  is  then  depressed  in  a  variety  of  ways ;  sometimes  by  a 
simple  lever,  at  other  times  by  a  treadle,  which  either  lowers  the 
shaft  only  one  single  sweep,  or  by  a  ratchet  that  brings  it  down  by 
several  small  successive  steps,  through  a  greater  distance ;  and 
mostly  a  counterpoise  weight  restores  the  parts  to  their  first  posi- 
tion when  the  hand  or  foot  is  removed.  Friction  clutches,  trains 
of  differential  wheels,  and  other  modes  are  also  used  in  depressing 
the  drill  spindle,  or  in  elevating  the  table  by  self-acting  motion. 
Frequently  also  the  platform  admits  of  an  adjustment  independent 
of  that  of  the  spindle,  for  the  sake  of  admitting  larger  pieces; 
the  horizontal  position  of  the  platform  is  then  retained  by  a  slide, 
to  which  a  rack  and  pinion  movement,  or  an  elevating  screw  is 
added. 

Drilling  machines  of  these  kinds  are  generally  used  with  the 
ordinary  piercing  drills,  and  occasionally  with  pin  drills ;  the  latter 
instrument  appears  to  be  the  type  of  another  class  of  boring  tools, 
namely,  cutter  bars,  which  are  used  for  works  requiring  holes  of 
greater  dimensions,  or  of  superior  accuracy,  than  can  be  attained 
by  the  ordinary  pointed  drills. 

The  small  application  of  this  principle,  or  of  cutter  bars,  is  shown 
on  the  same  scale  as  the  former  drills,  in  Fig.  414 ;  the  cutter  is 
placed  in  a  diametrical  mortise  in  a  cylindrical  boring  bar,  and  is 
fixed  by  a  wedge ;  the  cutter  extends  equally  on  both  sides,  as 
the  two  projections  or  ears  embrace  the  sides  of  the  bar,  which  is 
slightly  flattened  near  the  mortises. 

Cutter  bars  of  the  same  kind  are  occasionally  employed  with 
.cutters  of  a  variety  of  forms,  for  making  grooves,  recesses,  mould- 
ings, and  even  screws,  upon  parts  of  heavy  works,  and  those  which 
cannot  be  conveniently  fixed  in  the  ordinary  lathe.  Fig.  415  repre- 
sents one  of  these,  but  its  application  to  screws  will  be  found  in  the 
chapter  on  the  tools  for  screw  cutting. 

Figs.  414  416 


415 


The  larger  application  of  this  principle  is  shown  in  Fig.  415,  in 
which  a  east-iron  cutter-block  is  keyed  fast  upon  a  cylindrical  bar ; 
the  block  has  four,  six,  or  more  grooves  in  its  periphery.  Some- 


DRILLS.  411 

times,  the  work  is  done  with  only  one  cutter,  and  should  the  bar 
vibrate,  the  remainder  of  the  grooves  are  filled  with  pieces  of  hard 
wood,  so  as  to  complete  the  bearing  at  so  many  points  of  the  circle ; 
occasionally  cutters  are  placed  in  all  the  grooves,  and  carefully 
adjusted  to  act  in  succession,  that  is,  the  first  stands  a  little  nearer 
to  the  axis  than  the  second,  and  so  on  throughout,  in  order  that 
each  may  do  its  share  of  work ;  but  the  last  of  the  series  takes  only 
a  light  finishing  cut,  that  its  keen  edge  may  be  the  longer  pre- 
served. In  all  these  cutters,  the  one  face  is  radial,  the  other  dif- 
fers only  four  or  five  degrees  from  the  right  angle,  and  the  cor- 
ners of  thfc  tools  are  slightly  rounded. 

These  cutter  bars,  like  the  rest  of  the  drilling  and  boring  machin- 
ery, are  employed  in  a  great  variety  of  ways,  but  which  resolve 
themselves  into  three  principal  modes : 

First,  the  cutter  bar  revolves  without  endlong  motion,  in  fixed 
centres  or  bearings,  in  fact,  as  a  spindle  in  the  lathe ;  the  work  is 
traversed,  or  made  to  pass  the  revolving  cutter  in  a  right  line,  for 
which  end  the  work  is  often  fixed  to  a  traversing  slide  rest.  This 
mode  requires  the  bar  to  measure  between  the  supports,  twice  the 
length  of  the  work  to  be  bored,  and  the  cutter  to  be  in  the  middle 
of  the  bar ;  it  is  therefore  unfit  for  long  objects. 

Secondly,  the  cutter  bar  revolves,  and  also  slides  with  endlong 
motion,  the  work  being  at  rest ;  the  bearings  of  the  bar  are  then 
frequently  attached  in  some  temporary  manner  to  the  work  to  be 
bored,  and  are  often  of  wood.  Cylinders  of  forty  inches  diameter 
for  steam-engines,  have  been  thus  bored,  by  attaching  a  cast-iron 
cross  to  each  end  of  the  cylinder ;  the  crosses  are  bored  exactly  to 
fit  the  boring  bar,  one  of  them  carries  the  driving  gear,  and  the 
bar  is  thrust  endlong  by  means  of  a  screw,  moved  by  a  ratchet  or 
star  wheel. 

In  another  common  arrangement,  the  boring  bar  is  mounted  in 
headstocks,  much  the  same  as  a  traversing  mandrel,  the  work  is 
fixed  to  the  bearers  carrying  the  headstocks,  and  the  cutter  bar  is 
advanced  by  a  screw.  The  screw  is  then  moved  either  by  the 
hand  of  the  workman ;  by  a  star- wheel,  or  a  ratchet  wheel,  one 
tooth  only  in  each  revolution ;  or  else  by  a  system  of  differential 
wheels,  in  which  the  external  screw  has  a  wheel  say  of  50  teeth, 
the  internal  screw  a  wheel  of  51  teeth,  and  a  pair  of  equal  wheels 
or  pinions  drives  these  two  screws  continually,  so  that  the  ad- 
vance of  the  one-fiftieth  of  the  turn  of  the  screw,  or  their  differ- 
ence, is  equally  divided  over  each  revolution  of  the  cutter  bar, 
much  the  same  as  in  the  differential  motion  of  the  screw  drill, 
Fig.  404. 

This  second  method  only  requires  the  interval  between  the  fixed 
bearings  of  the  cutter  bar  to  be  as  much  longer  than  the  work  as 
the  length  of  the  cutter-block ;  but  the  bar  itself  must  have  more 
than  twice  the  length  of  the  work,  and  requires  to  slide  through 
the  supports. 

Cutter  bars  of  this  kind  are  likewise  used  in  the  lathe ;  in  the 


t 

412  THE  PEACTICAL   METAL-WORKER'S   ASSISTANT. 

act  of  boring,  the  end  of  the  bar  then  slides  like  a  piston  into  the 
mandrel.  Such  bars  are  commonly  applied  to  the  vertical  boring 
machines  of  the  larger  kinds,  which  are  usually  fitted  with  a  dif- 
ferential apparatus,  for  determining  the  progress  of  the  cut;  the 
bar  then  slides  through  a  collar  fixed  in  the  bed  of  the  machine. 

In  some  of  the  large  boring  machines  either  one  or  two  hori- 
zontal slides  are  added,  and  by  their  aid  series  of  holes  may  be 
bored  in  any  required  arrangement.  For  instance,  the  several 
holes  in  the  beams,  or  side  levers,  and  cranks  of  steam-engines,  are 
bored  exactly  perpendicular,  in  a  line,  and  at  any  precise  distances, 
by  shifting  the  work  beneath  the  revolving  spindle  uporw^he  guide 
or  railway ;  in  pieces  of  other  kinds,  the  work  is  moved  laterally 
during  the  revolution  of  the  cutters,  for  the  formation  of  elongated 
countersinks  and  grooves. 

Thirdly.  In  the  largest  applications  of  this  principle,  the  boring 
bar  revolves  upon  fixed  bearings  without  traversing ;  and  it  is 
only  needful  that  the  boring  bar  should  exceed  the  length  of  the 
work,  by  the  thickness  of  the  cutter  block,  of  which  it  has  com- 
monly several  of  different  diameters.  The  cutter  block,  now  some- 
F.  41-  times  ten  feet  diameter,  traverses  as  a 

slide  down  a  huge  boring  bar,  whose 
diameter  is  about  thirty  inches.  There 
is  a  groove  and  key  to  couple  them 
together,  and  the  traverse  of  the  cut- 
r-  ter  block  down  the  bar  is  caused  by 
a  side  screw,  upon  the  end  of  which 
is  a  large  wheel,  that  engages  in  a 
small  pinion,  fixed  to  the  stationary 
centre  or  pedestal  of  the  machine. 
With  every  revolution  of  the  cutter 
bar,  the  great  wheel  is  carried  around 
the  faced  pinion,  and  supposing  these 
be  as  ten  to  one,  the  great  wheel  is  moved  one-tenth  of  a  turn,  and 
therefore  moves  the  screw  one-tenth  of  a  turn  also,  and  slowly  trav- 
erses the  cutter  block. 

The  contrivance  may  be  viewed  as  a  huge,  self-acting,  and  re- 
volving sliding-rest,  and  the  diagram  417  shows  that  the  cutter 
bars  are  equally  applicable  to  portions  of  circles,  such  as  the  D 
valves  of  steam-engines,  as  well  as  to  the  enormous  interior  of  the 
cylinder  itself. 

All  the  preceding  boring  tools  cut  almost  exclusively  upon  the 
end  alone.  They  are  passed  entirely  through  the  objects,  and 
leave  each  part  of  their  own  particular  diameter,  and  therefore 
cylindrical  ;  but  I  now  proceed  to  describe  other  boring  tools,  that 
cut  only  on  their  sides,  go  but  partly  through  the  work,  and  leave 
its  section  a  counterpart  of  the  instrument.  These  tools  are  gen- 
erally conical,  and  serve  for  the  enlargement  of  holes  to  sizes 
intermediate  between  the  gradations  of  the  drills,  and  also  for  the 
iormation  of  conical  holes,  as  for  valves,  stopcocks,  and  other 


DRILLS.  413 

works.  The  common  pointed  drill,  or  its  multiplication  in  the  rose 
countersink,  is  the  type  of  the  series  ;  but  in  general  the  broaches 
have  sides  which  are  much  more  nearly  parallel. 

BROACHES  FOR  MAKING-  TAPER  HOLES.  —  The  tools  for  making 
taper  holes  are  much  less  varied  than  the  drills  and  boring  tools 
for  cylindrical  holes. 

Figs.  418   419    420   421   422    423 


424 


425. 

The  broaches  for  metal  are  made  solid,  and  of  various  section  s ; 
as  half-round,  like  Fig.  418 ;  the  edges  are  then  rectangular,  but 
more  commonly  the  broaches  are  polygonal,  as  in  Fig.  419,  except 
that  they  have  3,  4,  5,  6,  and  8  sides,  and  their  edges  measure 
respectively  60,  90,  108,  120,  and  135  degrees.  The  four,  five,  and 
six-sided  broaches  are  the  most  general,  and  the  watchmakers  em- 
ploy a  round  broach  in  which  no  angle  exists,  and  the  tool  is 
therefore  only  a  burnisher,  which  compresses  the  metal  and  rounds 
the  hole. 

Ordinary  broaches  are  very  acute,  and  Fig.  425  may  be  consid- 
ered to  represent  the  general  angle  at  which  their  sides  meet, 
namely,  less  than  one  or  two  degrees ;  the  end  is  usually  chamfered 
off  with  as  many  facets  as  there  are  sides,  to  make  a  penetrating 
point,  and  the  opposite  extremity  ends  in  a  square  tang,  or  shank, 
by  which  the  instrument  is  worked. 

Square  broaches,  after  having  been  filed  up,  are  sometimes 
twisted  whilst  red-hot ;  Fig.  424  shows  one  of  these  ;  the  rectan- 
gular section  is  but  little  disturbed,  although  the  faces  become 
slightly  concave.  The  advantage  of  the  tool  appears  to  exist  in 
its  screw  form :  when  it  is  turned  in  the  direction  of  the  spiral,  it 
cuts  with  avidity  and  requires  but  little  pressure,  as  it  is  almost 
disposed  to  dig  too  foreibly  into  the  metal :  when  turned  the  re- 
verse way,  as  in  unscrewing,  it  requires  as  much  or  more  pressure 
than  similar  broaches  not  twisted.  This  instrument,  if  bent  in  the 
direction  of  its  length,  either  in  the  act  of  twisting  or  hardening, 
does  not  admit  of  correction  by  grinding,  like  those  broaches  hav- 
ing plane  faces.  It  is  not  much  used,  and  is  almost  restricted  to 
wrought-iron  and  steel. 

Large  countersinks  that  do  not  terminate  in  a  point,  are  some- 
times made  as  solid  cones ;  a  groove  is  then  formed  up  one  side, 
and  deepest  towards  the  base  of  the  cone,  for  the  insertion  of  a 
cutter ;  see  Fig.  420.  As  the  blade  is  narrowed  by  sharpening,  it 


414  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

is  •  set  a  little  forward  in  the  direction  of  its  length,  to  cause  its 
edge  to  continue  slightly  in  advance  of  the  general  surface,  like 
the  iron  of  a  plane  for  cutting  metal. 

Figure  426  represents  the  broach,  invented  by  James  Kinse- 
laugh,  of  Wicklow,  Ireland,  in  which  four  detached  blades  are  intro- 
duced, for  the  sake  of  retaining  the  cone  or  angle  of  the  broach 

Fig.  428. 


with  greater  facility.  The  bar  or  stack  has  four  shallow  longitud- 
inal grooves,  which  are  nearly  radial  on  the  cutting  face,  and 
slightly  undercut  on  the  other.  The  grooves  are  also  rather 
deeper  behind,  and  the  blades  are  a  little  wedge-form  both  in  sec- 
tion and  in  length,  to  constitute  the  cone,  and  the  cutting  edges. 
In  restoring  the  edges  of  the  blades,  they  are  removed  from  the 
stock,  and  their  angles  are  then  more  easily  tested :  when  replaced, 
they  are  set  nearer  to  the  point,  to  compensate  for  their  loss  of 
thickness. 

Broaches  are  also  used  for  perfecting  cylindrical  holes,  as  well 
as  for  making  those  which  are  taper.  The  broaches  are  then  made 
almost  parallel,  or  a  very  little  the  highest  in  the  middle  ;  they  are 
filed,  with  two  or  three  planes  at  angles  of  90  degrees,  as  in  Figs. 
421  or  422.  The  circular  part  not  being  able  to  cut,  serves  as  a 
more  certain  base  or  foundation,  than  when  the  tool  is  a  complete 
polygon ;  and  the  stems  are  commonly  made  small  enough  to  pass 
entirely  through  the  holes,-  which  then  agree  very  exactly  as  to 
size.  Such  tools  are  therefore  rather  entitled  to  the  name  of  finish- 
ing drills,  than  broaches. 

The  size  of  the  parallel  broaches  is  often  slightly  increased  by 
placing  a  piece  or  two  of  paper  at  the  convex  part.  Leather  and 
thin  metal  are  also  used  for  the  same  purpose.  Gun-barrels  are 
broached  with  square  broaches,  the  cutting  parts  of  which  are 
about  eight  to  ten  inches  long  ;  they  are  packed  on  the  four  sides 
with  slips  or  spills  of  wood  to  complete  the  circle,  as  in  Fig.  423, 
in  which  the  tool  is  supposed  to  be  at  work.  The  size  of  the  bit 
is  progressively  enlarged  by  introducing  slips  of  thin  paper,  piece 
by  piece,  between  two  of  the  spills  of  wood  and  the  broach ;  the 
paper  throws  the  one  angle  more  towards  the  centre  of  the  hole, 
and  causes  a  corresponding  advance  in  the  opposite  or  the  cutting 
angle.  Sometimes,  however,  only  one  spill  of  wood  is  employed. 

A  broach  used  by  the  philosophical  instrument-makers  in  finish- 
ing the  barrels  of  air-pumps,  consisted  of  a  thin  plate  of  steel  in- 
serted diametrically  between  two  blocks  of  wood,  the  whole  con- 
stituting a  cylinder  with  a  scraping  edge  slightly  in  advance  of  the 
wood.  Slips  of  paper  were  also  added. 

According  to  the  size  of  the  broaches,  they  are  fixed  in  handles 


DRILLS.  415 

like  brad-awls ;  they  are  used  in  the  brace,  or  the  tap  wrench, 
namely,  a  double-ended  lever  with  square  central  holes.  Some- 
times also  broaches  are  used  in  the  lathe  just  like  drills,  and  for 
large  works  broaching  machines  are  employed.  These  are  little 
more  than  driving  gear  terminating  in  a  simple  kind  of  universal 
joint  to  lead  the  power  of  the  steam-engine  to  the  tool,  which  is 
generally  left  under  the  guidance  of  its  own  edges,  according  to 
the  .common  principle  of  the  instrument. 

In  drills  and  broaches  the  penetrating  angles  are  commonly  more 
obtuse  than  in  turning  tools  ;  thus  in  drills  of  limited  dimensions 
the  hook-form  of  the  turning  tool  for  iron  is  inapplicable,  and  in 
the  larger  examples  the  permanence  of  the  tool  is  of  more  conse- 
quence than  the  increased  friction.  But  on  account  of  the  ad- 
ditional friction  excited  by  the  nearly  rectangular  edges,  it  is 
commonly  necessary  to  employ  a  smaller  velocity  in  boring  than 
in  turning  corresponding  diameters,  in  order  to  avoid  softening  the 
tool  by  the  heat  generated ;  and  in  the  ductile  fibrous  metals,  as 
wrought-iron,  steel,  copper  and  others,  lubrication  with  oil,  water, 
etc.,  becomes  more  necessary  than  in  turning. 

The  drills  and  broaches  form  together  a  complete  series.  First, 
the  cylinder  bit,  the  pin  drills,  and  others  with  blunt  sides,  produce 
cylindrical  holes  by  means  of  cutters  at  right  angles  to  the  axis ; 
then  the  cutter  becomes  inclined  at  about  45  degrees,  as  in  the 
common  piercing  drill  and  cone  countersink ;  the  angle  becomes 
much  less  in  the  common  taper  broaches ;  and  finally  disappears 
in  the  parallel  broaches,  by  which  we  again  produce  the  cylin- 
drical hole,  but  with  cutters  parallel  with  the  axis  of  the  hole. 

Still  considering  the  drills  and  broaches  as  one  group,  the  drills 
have  comparatively  thin  edges,  always  less  than  90  degrees,  yet 
they  require  to  be  urged  forward  by  a  screw  or  otherwise,  the  re- 
sistance being  sustained  in  the  line  of  their  axes.  The  broaches 
have  much  more  obtuse  edges,  never  less  than  90,  and  sometimes 
extending  to  135  degrees ;  and  yet  the  greater  force  required  to 
cause  the  penetration  of  their  obtuse  edges  into  the  material  is 
supplied  without  any  screw,  because  the  pressure  in  all  these  varied 
tools  is  at  right  angles  to  the  cutting  edge. 

Thus  supposing  the  sides  of  the  broach  extended  until  they  meet 
in  a  point,  as  in  Fig.  425,  we  shall  find  the  length  will  very  many 
times  exceed  the  diameter,  and  by  that  number  will  the  force  em- 
ployed to  thrust  forward  the  tool  be  multiplied,  the  same  as  in  the 
wedge,  whether  employed  in  splitting  timber  or  otherwise ;  and 
the  broach  being  confined  in  a  hole,  it  cannot  make  its  escape,  but 
acts  with  lateral  pressure,  directed  radially  from  each  cutting  edge ; 
and  the  broach  under  proper  management  leaves  the  holes  very 
smooth  and  of  true  figure. 


416  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

CHAPTER  XXIII. 

SCREW-CUTTING  TOOLS. 

AN  elementary  idea  of  the  form  of  the  screw,  or  helix,  is  ob- 
tained by  considering  it  as  a  continuous  circular  wedge ;  and  it  is 
readily  modeled  by  wrapping  a  wedge-formed  piece  of  paper 
around  a  cylinder.  The  edge  of  the  paper  then  represents  the 
line  of  the  screw,  and  which  preserves  one  constant  angle  to  the 
axis  of  the  contained  cylinder,  namely,  that  of  the  wedge. 

The  ordinary  wedge,  or  the  diagonal,  may  be  produced  by  the 
composition  of  two  uniform,  rectilinear  motions,  which,  if  equal, 
produce  the  angle  of  45°,  or  if  unequal,  various  angles  more  or 
less  acute  ;  and  in  an  analogous  manner,  the  circular  wedge  or  the 
screw  may  be  produced  of  every  angle  or  coarseness  by  the  com- 
position of  an  uniform  circular  motion,  with  an  uniform  rectilinear 
motion.  And  as  either  the  rectilinear  or  the  circular  motion  may 
be  given  to  the  work  or  to  the  tool  indifferently,  there  are  four 
distinct  modes  of  producing  screws,  and  which  are  all  variously 
modified  in  practice. 

The  screw  admits  of  great  diversity.  It  may  possess  any  diame- 
ter ;  it  may  also  have  any  angle — that  is,  the  interval  between  the 
threa'ds  may  be  either  coarse  or  fine,  according  to  the  angle  of  the 
wedge  or  the  ratio  of  the  two  motions ;  and  the  wedge  may  be 
wound  upon  the  cylinder  to  the  right  hand  or  to  the  left,  so  as  to 
produce  either  right  or  left  hand  screws. 

The  idea  of  double,  triple,  or  quadruple  screws,  will  be  conveyed 
by  considering  two,  three,  or  four  black  lines  drawn  on  the  uncovered 
edge  of  the  wedge-formed  paper,  or  likewise  by  two,  three,  or  four 
strings  or  wires  placed  in  contact,  and  coiled  as  a  fiat  band  around 
the  cylinder,  the  angle  remains  unaltered,  it  is  only  a  multiplication 
of  the  furrows  or  threads ;  and  lastly,  the  screw  may  have  any 
section,  that  is,  the  section  of  the  worm  or  thread  may  be -angular, 
square,  round,  or  of  any  arbitrary  form.  Thus  far  as  to  the  variety 
in  screws. 

The  importance  of  this  mechanical  element,  the  screw,  in  all 
works  in  the  constructive  arts,  is  almost  immeasurable.  For  in- 
stance, great  numbers  of  screws  are  employed  merely  for  connect- 
ing together  the  different  parts  of  which  various  objects  are  com- 
posed ;  no  other  attachment  is  so  compact,  powerful,  or  generally 
available ;  these  binding  or  attachment  screws  require,  by  compari- 
son, the  least  degree  of  excellence.  Other  screws  are  used  as  regu- 
lating screws,  for  the  guidance  of  the  slides  and  the  moving  parts 
of  machinery,  for  the  screws  of  presses  and  the  like  ;  these  kinds 
should  possess  a  much  greater  degree  of  excellence  than  the  last. 
But  the  most  exact  screws  that  can  be  produced,  are  quite  essen- 
tial to  the  good  performance  of  the  engines  employed  in  the  grad- 


SCREW-CUTTING   TOOLS.  417 

j>"  * 

nation  of  right  lines  and  circles,  and  of  astronomical  and  mathe- 
matical instruments;  in  these  delicate  micromdrical  screws,  our 
wants  ever  appear  to  outstrip  the  most  refined  methods  of  ex- 
ecution. 

The  attempt  to  collect  and  describe  all  the  ingenious  contriv- 
ances which  have  been  devised  for  the  construction  of  screws, 
would  be  in  itself  a  work  of  no  ordinary  labor  or  extent :  I  must, 
therefore,  principally  restrict  myself  to  those  varied  processes  now 
commonly  used  in  the  workshops,  for  producing  with  comparative 
facility,  screws  abundantly  exact  for  the  great  majority  of  pur- 
poses. It  has  been  found  rather  difficult  to  arrange  these  ex- 
tremely different  processes  in  tolerable  order,  but  that  which  seems 
to  be  the  natural  order  has  been  adopted,  thus : — 

There  appears  to  be  no  doubt,  but  that  in  the  earliest  produc- 
tion of  the  apparatus  for  cutting  screws,  the  external  screw  was 
the  first  piece  made ;  this  plain  circular  metal  screw  was  serrated 
and  thus  converted  into  the  tap,  or  cutting  tool,  by  which  internal 
screws  of  corresponding  size  and  form  were  next  produced ;  and 
one  of  these  hollow  screws  or  dies  became  in  its  turn  the  means  of 
regenerating,  with  increased  truth  and  much  greater  facility,  any 
number  of  copies  of  the.  original  external  screw.  In  these  several 
stages  there  is  a  progressive  advance  towards  perfection,  as  will  be 
hereafter  adverted  to. 

These  hand  processes  are  mostly  used  for  screws,  which  are  at 
least  as  long,  if  not  longer  than  their  diameters.  The  rotatory 
and  rectilinear  guides,  and  the  one  or  several  series  of  cutting 
points,  are  then  usually  combined  within  the  tool.  This  first  group 
will  be  considered  in  the  succeeding  order : — 

On  originating  screws. 

On  cutting  internal  screws,  with  screw  taps. 

On  cutting  external  screws,  with  screw  dies. 

Subsequent  improvements  have  led  to  the  employment  of  the 
lathe  in  producing  from  the  above,  and  in  a  variety  of  ways,  still 
more  accurate  screws.  These  methods  are  sometimes  used  for 
screws  which  possess  only  a  portion  of  a  turn,  at  other  times  for 
screws  twenty  or  thirty  feet  long  and  upwards.  The  rotatory 
guide  is  always  given  by  the  mandrel,  the  rectilinear  guide  is  vari- 
ously obtained,  and  the  detached  screw  tool  or  cutter,  may  have 
one  single  point,  or  one  series  of  points  which  touch  the  circle  at 
only  one  place  at  a  time.  This  second  group  will  be  arranged 
thus : — 

On  cutting  screws,  in  the  common  lathe  by  hand. 

On  cutting  screws,  in  lathes  with  traversing  mandrels. 

On  cutting  screws,  in  lathes  with  traversing  tools. 

It  may  be  further  observed  that  the  modes  described  under  these 
heads  are  in  general  applied  to  very  different  purposes,  and  are 
only  to  a  limited  extent  capable  of  substitution  one  for  the  other ; 
it  is  to  be  also  remarked  that  it  has  been  considered  convenient,  in 
a  great  measure  to  abandon,  or  rather  to  modify,  the  usual  dis- 
27 


418  THE   PRACTICAL   METAL-TVORKER  S  ASSISTANT. 

tinction  between  the  tools  respectively  used  for  wood  and  for 
metal.  The  eighth  and  concluding  section  of  this  subject  describes 
some  refinements  in  the  production  of  screws  which  are  not  com- 
monly practiced,  and  it  is  in  some  measure  a  sequel  to  the  second 
section.  , 

ON  ORIGINATING  SCREWS. — It  appears  more  than  probable,  that 
in  the  earliest  attempts  at  making  a  screw,  a  sloping  piece  of  paper 
was  cemented  around  the  iron  cylinder ;  this  oblique  line  was  cut 
through  with  a  stout  knife  or  a  thin  edged  file,  and  was  then 
gradually  enlarged  by  hand  until  it  gave  a  rude  form  of  screw. 
Doubtless  as  soon  as  the  application  of  the  lathe  was  generally 
.known,  the  work  was  mounted  between  centres,  so  that  the  prog- 
ress of  filing  up  the  groove  could  be  more  easily  accomplished, 
or  a  pointed  turning  tool  could  be  employed  to  assist.  Such,  in 
fact,  is  one  of  the  modes  recommended  by  Plumier,  for  cutting  the 
screw  upon  a  lathe  mandrel  for  receiving  the  chucks,  even  in  pref- 
erence to  the  use  of  the  die-stocks,  which,  he  urged,  were  liable 
to  bend  the  mandrel  in  the  act  of  cutting  the  screw. 

Nearly  similar  modes  have  been  repeatedly  used  for  the  pro- 
duction of  original  screws;  one  account  differing  in  several  re- 
spects from  the  above,  is  described  as  having  been  very  success- 
fully resorted  to  above  fifty  years  back,  at  the  Soho  works,  Birm- 
ingham, by  a  workman  of  the  name  of  Joe  Baggs,  before  the  in- 
troduction of  the  screw-cutting  lathe.  This  is  an  English  account 
of  an  English  supposed  invention. 

The  screw  was  seven  feet  long,  six  inches  diameter,  and  of  a 
square  triple  thread ;  after  the  screw  was  accurately  turned  as  a 
cylinder,  the  paper  was  cut  parallel  exactly  to  meet  around  the 
same,  and  was  removed  and  marked  in  ink  with  parallel  oblique 
lines,  representing  the  margins  of  the  threads ;  and  having  been 
replaced  on  the  cylinder,  the  lines  were  pricked  through  with  a 
centre  punch.  The  paper  was  again  removed,  the  dots  were  con- 
nected by  fine  lines  cut  in  with  a  file,  the  spaces  were  then  cut  out 
with  a  chisel  and  hammer  and  smoothed  with  a  file,  to  a  sufficient 
extent  to  serve  as  a  lead  or  guide. 

The  partly  formed  screw  was  next  temporarily  suspended  in  the 
centre  of  a  cast-iron  tube  or  box  strongly  fixed  against  a  horizontal 
beam,  and  melted  lead  mixed  with  tin,  was  poured  into  the  box  to 
convert  it  into  a  guide  nut ;  it  then  only  remained  to  complete  the 
thread  by  means  of  cutters  fixed  against  the  box  or  nut,  but  with 
the  power  of  adjustment,  in  fact  in  a  kind  of  slide-rest,  the  screw 
being  handed  round  by  levers. 

Another  very  simple  way  of  originating  screws,  and  which  is 
sufficiently  accurate  for  some  purposes,  is  to  coil  a  small  wire 
around  a  larger  straight  wire  as  a  nucleus  ;  this  last  is  frequently 
the  same  wire  the  one  end  of  which  is  to  be  cut  into  the  screw. 
The  covering  wire,  whose  diameter  is  equal  to  the  space  required 
between  the  threads  of  the  screw,  is  wound  on  close  and  tight,  and 
made  fast  at  each  end.  The  coiled  screw,  being  enclosed  between 


SCREW-CUTTING  TOOLS.  419 

two  pieces  of  hard  wood,  indents  a  hollow  or  counterpart  thread, 
sufficient  to  guide  the  helical  traverse,  and  a  fixed  cutter  completes 
this  simple  apparatus. 

Common  screws,  for  some  household  purposes,  have  been  made 
of  tinned  iron  wire ;  two  covering  wires  are  rolled  on  together,  the 
one  being  removed  leaves  a  space  such  as  the  ordinary  hollow  of 
the  thread,  and  when  these  screws  are  dipped  in  a  little  melted  tin, 
the  two  wires  become  soldered  together. 

Other  modes  have  been  resorted  to  for  making  original  screws, 
by  indenting  a  smooth  cylinder  with  a  sharp-edged  cutter  placed 
across  the  same  at  the  required  angle,  and  trusting  to  the  surface 
or  rolling  contact  to  produce  the  rotation  and  traverse  of  the 
cylinder,  with  the  development  of  the  screw.  In  the  most  simple 
application  of  this  method  a  deep  groove  is  made  along  a  piece  of 
board  in  which  a  straight  wire  is  buried  a  little  beneath  the  sur- 
face. A  second  groove  is  made  nearly  at  right  angles  across  the 
first,  exactly  to  fit  the  cutter,  which  is  just  like  a  table  knife,  and 
is  placed  at  the  angle  required  in  the  screw.  The  cutter  when 
slid  over  the  wire  indents  it,  carries  it  round,  and  traverses  it  end- 
ways in  the  path  of  a  screw.  A  helical  line  is  thus  obtained, 
which,  by  cautious  management,  may  be  perfected  into  a  screw 
sufficiently  good  for  many  purposes. 

Mr.  Walsh,  of  Dublin,  employed  a  cutter  upon  cylinders  of 
wood,  tin,  brass,  iron,  and  other  materials,  mounted  to  revolve 
between  centres  in  a  triangular  bar  lathe ;  the  knife  was  hollowed 
to  fit  the  cylinder,  and  fixed  at  the  required  angle  on  a  block 
adapted  to  slide  upon  the  bar ;  the  oblique  incision  carried  the 
knife  along  the  revolving  cylinder.  Some  hundreds  of  screws 
were  thus  made,  and  their  agreement  with  one  another  was  in  many 
instances  quite  remarkable.  On  the  whole  he  gave  the  preference 
to  this  mode  of  originating  screws. 

The  apparatus  for  originating  screws  for  astronomical  and  other 
purposes  is  represented  in  plan  in  Fig.  427,  in  side  elevation  in 
Fig.  428,  and  429  is  the  front  elevation  of  the  cutter  frame  alone. 
This  method  is  also  due  to  Mr.  Walsh.  The  piece  intended  for 
the  screw,  namely,  a  a,  Fig.  427,  is  turned  cylindrical,  and  with  two 
equal  and  cylindrical  necks  ;  it  is  supported  in  a  metal  frame  with 
two  semi-circular  bearings,  b  b,  which  are  fixed  on  a  slide  moved 
by  an  adjusting  screw  c. 

The  instrument  generates  original  screws  perfectly  true,  of  -any 
number  of  threads,  and  right  or  left  handed.  In  this  case,  the 
stock  and  cutter  are  made  as  in  Figs.  437,  428,  and  429  ;  the  back 
of  the  stock  is  made  into  the  segment  of  a  circle,  s ;  and  the  top 
of  the  cutter  is  continued  into  an  index,  t.  The  cutter  is  a  single 
thread,  and  moves  on  its  edge,  v,  as  a  centre.  This  must  fit  true, 
and  the  stock  fit  close  to  the  cutter,  to  keep  it  perfectly  steady ; 
u,  u,  two  screws,  to  'adjust  and  fasten  the  cutter  to  any  required 
angle.  The  cutter  should  be  rather  elliptical,  for  it  is  best  to  fit 
well  to  the  cylinder  at  the  greatest  angle  it  will  be  ever  used. 


420 


THE   PEACTICAL   METAL-WOEKER  S   ASSISTANT. 


When  one  turn  has  been  given  to  the  cylinder,  Fig.  427,  a  tooth,  w, 
is  put  into  the  cut,  and  screwed  fast.     This  tooth  secures  the 


lead,  and  causes  every  following  thread  to  be  a  repetition  of  the 
first ;  and  though  it  might  do  without,  yet  this  is  a  satisfactory 
security. 

In  cutting  ordinary  screws,  the  dies  shown  separately  in  Figs. 
430  to  433,  the  consideration  of  which  is  for  the  present  deferred, 
takes  the  place  of  the  oblique  cutter  in  the  former  figures. 

The  screw  is  also  originated  by  traversing  the  tool  in  a  right 
line  alongside  a  plain  revolving  cylinder.  Sometimes  the  tool  has 
many  points,  and  is  guided  by  the  hand  alone ;  at  other  times  the 
tool  has  but  one  single  point,  and  is  guided  mechanically  so  as  to 
proceed,  say  one  inch  or  one  foot  in  a  right  line,  whilst  the  cylin- 
der makes  a  definite  number  of  revolutions.  The  tool  is  then 
traversed  either  by  a  wedge  placed  transversely  to  the  axis,  by  a 
chain  or  metallic  band  placed  longitudinally,  or  by  another  screw 
connected  in  various  ways  with  the  screw  to  be  produced,  by 
wheel-work  and  other  contrivances. 

ON  CUTTING  INTERNAL  SCREWS,  WITH  SCREW  TAPS.— The  screw 
is  converted  into  the  tap  by  the  removal  of  parts  of  its  circumfer- 
ence, in  order  to  give  to  the  exposed  edges  a  cutting  action ;  whilst 
the  circular  parts  which  remain,  serve  for  the  guidance  of  the  in- 
strument within  the  helical  groove,  or  hollow  thread,  it  is  required 
to  form. 


SCREW-CUTTING  TOOLS.  421 

In  the  most  simple  and  primitive  method,  four  planes  were  filed 
upon  the  screw,  as  in  Fig.  434,  but  this  exposes  very  obtuse  edges 
which  can  hardly  be  said  to  cut,  as  they  form  the  thread  partly  by 
indenting,  and  partly  by  raising  or  burring  up  the  metal ;  and  as 
such  they  scarcely  produce  any  effect  in  cast-iron  or  other  crysjtal- 
line  materials.  Conceiving,  as  in  Fig.  434,  only  a  very  small  por- 
tion of  the  circle  to  remain,  the  working  edges  of  squared  taps, 
form  'angles  of  (90  -f  45  or)  135  degrees  with  the  circumference, 
and  the  angle  is  the  greater,  the  more  of  the  circle  that  remains. 
It  is  better  to  file  only  three  planes,  as  in  Fig.  435,  but  the  angle 
is  then  as  great  as  120  degrees  even  under  the  most  favorable  cir- 
cumstances. 

In  taps  of  the  smallest  size  it  is  imperative  to  submit  to  these 
conditions,  and  to  employ  the  above  sections.  Sometimes  small 
intermediate  facets  or  planes  are  tipped  off  a  little  obliquely  with 
the  file,  to  relieve  the  surface  friction ;  this  gives  the  instrument 
partly  the  character  of  a  six  or  eight  sided  broach,  and  improves 
the  cutting  action. 


439. 


There  appears  to  be  no  doubt  that,  for  general  purposes,  the 
most  favorable  angle  for  the  edges  of  the  screw  taps  and  dies  is 
the  radial  line,  or  an  angle  of  90  degrees.  This  condition  mani- 
festly exists  in  the  half-round  tap,  Fig.  436.  I  propose  that  this 
should  be  made  half-round,  as  it  will  be  found  that  a  tap  formed 
in  this  way  will  cut  a  full  clear  thread  (even  if  it  may  be  of  a 
sharp  pitch),  without  making  up  any  part  of  it  by  the  burr,  as  is 
almost  universally  the  case  when  blunt-edged  or  grooved  taps  are 
used. 

It  has  sometimes  been  objected  to  me  by  persons  who  had  not 
seen  half-round  taps  in  use,  that  from  their  containing  less  substance 
than  the  common  forms  do,  they  must  be  very  liable  to  be  broken 
by  the  strain  required  to  turn  them  in  the  work.  It  is  proved, 
however,  by  experience,  that  the  strain  in  their  case  is  so  much 
smaller  than  usual,  that  there  is  even  less  chance  of  breaking  them 
than  the  stouter  ones.  Workmen  are  aware  that  a  half-round 
opening  bit  makes  a  better  hole  and  cuts  faster  than  a  five  sided 
one,  and  yet  that  it  requires  less  force  to  use  it. 

Fig.  437,  in  which  two-thirds  of  the  circle  are  allowed  to  remain, 
has  been  also  employed  for  taps;  this,  although  somewhat  less 
penetrative  than  the  last,  is  also  less  liable  to  displacement  with 
the  tap  wrench.  It  is  much  more  usual  to  employ  three  radial 
cutting  edges  instead  of  one  only :  and  as  in  the  best  forms  of  taps, 
they  are  only  required  to  cut  in  the  one  direction,  or  when  they 


422 


THE   PRACTICAL   METAL -WORKER'S   ASSISTANT. 


are  screwed  into  the  nut,  the  other  edges  are  then  chamfered  to 
make  room  for  the  shavings ;  thereby  giving  the  tap  a  section 
somewhat  like  that  of  a  ratchet  wheel,  with  either  three,  four,  or 
five  teeth,  as  in  Figs.  438  and  446. 

It  is  more  common,  however,  either  to  file  up  the  side  of  the 
tap,  or  to  cut  by  machinery,  three  concave  or  elliptical  flutes,  as  in 
439 ;  this  form  sufficiently  approximates  to  the  desideratum  of  the 
radial  cutting  edges,  it  allows  plenty  of  room  for  the  shavings, 
and  is  easily  wiped  out.  What  is  of  equal  or  greater  importance, 
it  presents  a  symmetrical  figure,  little  liable  to  accident  in  the 
hardening,  either  of  distortion  from  unequal  section,  as  in  Figs. 
436  and  437,  or  of  cracking  from  internal  angles  as  in  437  and  438. 

Still,  considering  alone  the  transverse  section  of  the  tap,  it  will 
be  conceived  that  before  any  of  the  substance  can  be  removed  from 
the  hole  that  is  being  tapped,  the  circular  part  of  the  instrument 
must  become  embedded  into  the  metal  a  quantity  equal  to  the 
thickness  of  the  shaving;  and  in  this  respect  Figs.  434  and  435,  in 
which  the  circular  parts  are  each  only  the  tenth  or  twelfth  of  the 
circumference,  appear  to  have  the  advantage  over  the  modern  taps 
438  and  439,  in. which  each  arc  is  twice  as  long.  Such,  however, 
is  not  the  case,  as  the  first  two  act  more  in  the  manner  of  the 
broach,  if  we  conceive  that  instrument  to  have  serrated  edges ;  but 
Figs.  438  and  439  act  nearly  as  turning  tools,  as  in  general  the 
outer  or  the  circular  surface  is  slightly  relieved  with  a  file,  so  as 
to  leave  the  cutting  edges  a,  somewhat  in  advance  of  the  general 
periphery ;  which  is  equivalent  to  chamfering  the  lower  plane  of 
the  turning  tool  some  three  degrees  to  produce  that  relief  which 
has  been  appropriately  named  the  angle  of  separation. 

But  in  the  tap  Fig.  440,  invented  by  F.  O'Neal,  this  is  still  more 


Figs.  440 


441 


442 


443. 


effectually  accomplished.  The  instrument,  instead  of  being  turned 
of  the  ordinary  circular  section  in  the  lathe  (or  as  the  outer  dotted 
line),  is  turned  with  three  slight  undulations,  by  means  of  an  alter- 
nating radial  motion  given  to  the  tool.  From  this  it  results  that, 
when  the  summits  of  these  hills  are  converted  into  the  cutting 
edges,  that  not  only  are  the  extreme  edges  or  points  of  the  teeth 


SCREW-CUTTIXG  TOOLS.  423 

made  prominent,  but  the  entire  serrated  surface  becomes  inclined  at 
about  the  three  decrees  to  the  external  circle,  or  the  line  of  work, 
so  as  exactly  to  assimilate  to  the  turning  tool ;  and  therefore  there 
is  little  doubt  but  that,  under  equal  circumstances,  O'Neal's  tap 
would  work  with  less  friction  than  any  other. 

The  principle  of  chamfering,  or  relieving  the  taps,  must  not, 
however,  be  carried  to  excess,  or  it  will  lead  to  mischief.  For  ex- 
ample, the  tap,  if  sloped  behind  the  teeth  as  is  Fig.  441,  would  be 
much  exposed  to  fracture;  and  the  instrument  being  entirely  under 
its  own  guidance,  the  three  series  of  keen  points  would  be  apt  to 
stick  irregularly  into  the  metal,  and  would  not  produce  the  smooth, 
circular,  or  helical  hole,  obtained  when  the  tool,  Fig.  442,  is  used. 
The  relief  should  be  slight,  and  the  surfaces  of  the  teeth  then 
assimilate  to  the  condition  of  the  graver  for  copper  plates,  and 
thereby  direct  the  tap  in  a  very  superior  manner. 

The  teeth  sloped  in  front,  as  in  Fig.  443,  would  certainly  cut 
more  keenly  than  those  of  442,  but  they  would  be  much  more  ex- 
posed to  accident,  as  the  least  backward  motion  or  violence  would 
be  liable  to  snip  off  the  keen  points  of  the  teeth ;  and  therefore,  on 
the  score  of  general  economy  and  usefulness,  the  radial  and  slightly 
relieved  teeth  of  Fig.  442,  or  rather  of  439,  are  proper  for  work- 
ing taps. 

It  appears  further  to  be  quite  impolitic,  entirely  to  expunge  the 
surface-bearing,  or  squeeze,  from  the  taps  and  dies,  when  these  are 
applied  to  the  ductile  metals ;  as  not  only  does  it,  when  slight, 
greatly  assist  in  the  more  perfect  guidance  of  the  instrument,  but 
it  also  serves  somewhat  to  condense  or  compress  the  metal. 

Unless  the  taps  cut  very  freely,  it  is  the  general  aim  to  avoid 
the  necessity  for  tapping  cast-iron,  which  is  a  granular  and  crystal- 
line substance,  apt  to  crumble  away  in  the  tapping,  or  in  the  after 
use.  The  general  remedy  is  the  employment  of  bolts  and  nuts 
made  of  wrought-iron,  or  fixing  screwed  wrought-iron  pins  in  the 
work,  by  means  of  transverse  keys  and  other  contrivances,  and 
sometimes  by  the  insertion  of  plugs  of  gun-metal,  to  be  afterwards 
tapped  with  the  screw-threads.  In  general  also,  the  small  screws 
for  cast-iron  are  coarse  and  shallow  in  the  thread  compared  with 
those  for  wrought-iron,  steel,  and  brass. 

The  transverse  sections  hitherto  referred  to,  are  always  used  for 
those  taps  employed  in  screwing  the  inner  surfaces  of  the  nuts,  and 
holes  required  in  general  mechanism.  The  longitudinal  section  of 
the  working  tap  is  taper  and  somewhat  like  a  broach,  the  one  end 
being  small  enough  in  external  diameter  to  enter  the  blank  hole  to 
be  screwed,  and  the  other  end  being  as  large  as  the  screw  for  which 
the  nut  is  intended. 

In  many  cases  a  series  of  two,  three,  or  four  taps  must  be  used 
instead  of  only  one  single  conical  tap,  and  the  modifications  in 
their  construction  are  explained  by  the  following  diagrams ;  namely, 
Fig.  444,  the  tap  formerly  used  for  nuts  and  thoroughfare  holes, 
and  Fig.  445,  the  modern  tap  for  the  same  purposes :  the  dotted 
lines  in  each  represent  the  bottoms  of  the  threads. 


424 


THE    PRACTICAL    METAL-WORKER'S   ASSISTANT. 


In  the  former  kind,  the  thread  was  frequently  finished  of  a  taper 
figure,  with  the  screw  tool  in  the  lathe  ;  after  which  either  the  four 
or  three  plane  surfaces  were  filed  upon  it,  as  shown  by  the  section 
at  s ;  the  neck  from  ftog  was  as  small  as  the  bottom  of  the  thread, 
and 'the  tang  from  g  to  h  was  either  square  or  rectangular  for  the 
tap  wrench.  The  tang,  if  square,  was  also  taper,  the  tap  wrench 
then  wedged  fast  upon  the  tap ;  the  sides  of  the  tang,  if  parallel, 
were  rectangular,  and  measured  as  about  one  to  two,  and  there 
were  shoulders  on  two  sides  to  sustain  the  wrench. 

Fig.  444. 


Fig.  445. 


In  the  modern  thoroughfare  taps  for  nuts,  drawn  to  the  same 
scale  in  Fig.  445,  the  thread  is  left  cylindrical,  from  the  screw  tool 
or  the  dies ;  then  from  a  to  b,  or  about  one  diameter  in  length,  is 
turned  down  cylindrical  until  the  thread  is  nearly  obliterated  ; 
from  d  to  /  also  nearly  one  diameter  in  length  at  the  other  end,  is 
left  of  the  full  size  of  the  bolt,  and  the  intermediate  part,  b  to  d, 
equal  to  three  or  four  diameters,  is  turned  to  a  cone,  after  which 
the  tap  is  fluted  as  seen  at  s.  The  neck  /  g,  as  before,  is  as  small 
as  the  bottom  of  the  thread,  and  the  square  g  h,  measures  diagon- 
ally the  same  as  the  turned  neck. 

In  using  the  modern  instrument,  Fig.  445,  the  hole  to  be  tapped 
is-  bored  out  exactly  to  fit  the  cylindrical  plug  a  b,  which  therefore 
guides  the  tap  very  perfectly  in  the  commencement ;  the  tool  is 
simply  passed  once  through,  the  nut  without  any  retrograde  motion 
whatever,  and  the  cylindrical  part  d  f,  takes  up  the  guidance  when 
the  larger  end  of  the  cone  enters  the  hole ;  at  the  completion,  the 
tap  drops  through,  the  head  being  smaller  than  the  bottom  of  the 
thread.  The  old  four  square  taps  could  not  be  thus  used,  for  as 
they  rather  squeezed  than  cut,  they  had  much  more  friction ;  it 
was  necessary  to  move  them  backwards  and  forwards,  and  to  make 
the  square  for  the  wrench  larger,  to  avoid  the  risk  of  twisting  off 
the  head  of  the  tap.  In  taps  of  modern  construction  of  less  than 
half  an  inch  diameter,  it  is  also  needful  to  make  the  squares  larger 
than  the  proportion  employed  in  Fig.  445. 

In  tapping  shallow  holes,  as  only  a  small  portion  of  the  end  of 


SCREW-CUTTIXG   TOOLS.  425 

the  tap  can  be  used,  the  screwed  part  seldom  exceeds  two  diame- 
ters in  length,  and  as  they  will  not  take  hold  when  made  too  coni- 
cal, a  succession  of  three  or  four  taps  is  generally  required.  The 
screwed  part  of  the  first  may  be  considered  to  extend  from  a  to  b 
of  Fig.  444,  of  the  second,  from  c  to  d,  of  the  third  from  e  to  /; 
so  that  the  prior  tap  may,  in  each  case,  prepare  for  the  reception 
of  the  following  one.  The  taps  are  generally  made  in  sets  of 
three ;  the  first,  which  is  also  called  the  entering  or  taper  tap,  is  in 
most  cases  regularly  taper  throughout  its  length ;  the  second,  of 
the  middle  tap,  is  sometimes  taper,  but  more  generally  cylindrical, 
with  just  two  or  three  threads  at  the  end  tapered  off;  the  third 
tap,  which  is  also  called  the  plug  or  finishing  tap,  is  always  cylin- 
drical, except  at  the  two  or  three  first  threads,  which  are  slightly 
reduced. 

Taps  are  used  in  various  ways,  according  to  the  degree  of 
strength  required  to  move  them.  The  smallest  taps  should  have 
considerable  length,  and  should  be  fixed  exactly  in  the  axis  of 
straight  handles ;  the  lengtn  serves  as  an  index  by  which  the  true 
position  of  the  instrument  can  be  verified  in  the  course  of  work ; 
with  the  same  view  as  to  observation,  and  as  an  expeditious  mode, 
taps  of  a  somewhat  larger  size  are  driven  round  by  a  hand  brace, 
whilst  the  work  is  fixed  in  the  vice.  Still  larger  taps  require  tap 
wrenches,  or  levers  with  central  holes  to  fit  the  square  ends  of  the 
taps ;  for  screw  taps  from  one  to  two  inches  diameter,  the  wrenches 
have  assumed  the  lengths  of  from  four  to  eight  feet,  although  the 
recent  improvements  in  the  taps  have  reduced  the  lengths  of  the 
wrenches  to  one-half. 

Notwithstanding  that  the  hole  to  be  tapped  may  have  been 
drilled  straight,  the  tap  may  by  improper  direction  proceed  ob- 
liquely ;  the  progress  of  the  operation  should  be  therefore  watched, 
and  unless  the  eye  serve  readily  for  detecting  any  falseness  of 
position,  a  square  should  be  laid  upon  the  work,  and  its  edge  com- 
pared with  the  axis  of  the  tap  in  two  positions. 

In  tapping  deeply  seated  holes,  the  taps  are  temporarily  length- 
ened by  sockets,  frequently  the  same  as  those  used  in  drilling, 
which  are  represented  in  Fig.  401,  page  403  ;  the  tap  wrench  can 
then  surmount  those  parts  of  the  work  which  would  otherwise 
prevent  its  application. 

Sometimes  for  tapping  two  distant  holes  exactly  in  one  line,  the 
ordinary  taper  tap.  Fig.  445,  is  made  with  the  small  cylindrical 
part  a  b  exceedingly  long,  so  as  to  reach  from  the  one  hole  to  the 
other  and  serve  as  a  guide  or  director.  This  is  only  an  extension 
of  the  short  plug  a  b,  Fig.  445,  which  it  is  desirable  to  leave  on 
most  taps  used  for  thoroughfare  holes. 

Some  works  are  tapped  whilst  they  are  chucked  on  the  lathe 
mandrel ;  in  this  case  the  shank  of  the  tap,  if  in  false  position, 
will  swing  round  in  a  circle  whilst  the  mandrel  revolves,  instead 
of  continuing  quietly  in  the  axis  of  the  lathe.  Sometimes  the  centre 
point  of  the  popit-head  is  placed  in  the  centre  hole  in  the  head  of 


426  THE'  PRACTICAL  METAL- WORKER'S  ASSISTANT. 

the  tap ;  in  those  which  are  fixed  iii  handles  it  is  better  the  handle 
of  the  tap  should  be  drilled  up  to  receive  the  cylinder  of  the  popit- 
head,  as  in  the  lathe  taps  for  making  chucks ;  this  retains  the  guid- 
ance more  easily. 

Taps  of  large  size,  as  well  as  the  generality  of  cutting  instru- 
ments, have  been  constructed  with  detached  cutters.  For  those 
exceeding  about  1|  inch  diameter,  two  steel  plugs  a  a,  may  be  in- 
serted within  taper  holes  in  the  body  of  the  tap,  as  represented  in 
Fig.  446,  and  in  the  two  sections  b  and  c ;  the  whole  is  then  screwed 
and  hardened. 

Fig.  446. 


The  advance  of  the  cutters  slightly  beyond  the  general  line  of 
the  thread,  is  caused  by  placing  a  piece  of  paper  within  the  mor- 
tises a  b,  and  to  relieve  the  surface  friction,  each  alternate  tooth  in 
the  middle  part  of  the  length  of  the  tap  is  filed  away.  Sometimes 
the  cutters  are  parallel  and  inserted  only  partway  through,  and  are 
then  projected  by  set  screws  placed  also  on  the  diameter,  as  in  the 
section  c. 

The  cutter  bar,  Fig.  415,  p.  410,  may  also  be  viewed  as  a  tap 
with  detached  cutters.  The  cylindrical  bar  is  supported  in  tem- 
porary fixed  bearings,  one  of  which  embraces  the  thread  (some- 
times by  having  melted  load  poured  around  the  same),  the  bar 
moves  therefore  in  the  path  of  a  screw.  In  cutting  the  external 
thread,  the  cutter  represented  is  shifted  inwards  with  the  progress 
of  the  work  ;  or  a  straight  cutter  shifted  outwards,  serves  for  mak- 
ing an  internal  screw ;  pointed  instead  of  serrated  cutters  may  be 
also  used ;  they  are  frequently  adjusted  by  a  set  screw  instead  of 
the  hammer,  and  are  worked  by  a  wrench. 

This  screw  cutter  bar,  independently  of  its  use  for  large  awk- 
ward works,  is  also  employed  for  cutting,  in  their  respective  situa- 
tions, screws  required  to  be  exactly  in  a  line  with  holes  or-  fixed 
bearings,  as  the  nuts  of  slides,  presses,  and  similar  works. 
-•  Some  taps  or  cutters  are  made  cylindrical,  and  are  used  for  cut- 
ting narrow  pieces  and  edges,  such  as  screw-cutting  dies,  screw 
tools,  and  worm  wheels ;  therefore  it  is  necessary  to  leave  much 
more  of  the  circle  standing,  and  to  make  the  notches  narrower 
than  the  width  of  the  smallest  pieces  to  be  cut.  But  the  grooves 
should  still  possess  radial  sides,  and  when  these  are  connected  by 
a  curved  line,  as  in  Fig.  447,  there  is  less  risk  of  accident  in  the 
hardening.  The  number  of  the  notches  increases  with  the  diame- 
ter, but  the  annexed  figure  would  be  better  proportioned  if  it  had 


SCBEW-CUTTIXG    TOOLS.  427 

one  or  two  less  notches,  as  inadvertently  the  teeth  have  been 
drawn  too  weak. 

When  the  tool,  Figs.  447  and  448,  is  used  for  cutting  the  dies  of 
die  stocks  it  is  called  an  original  tap,  of  which  further  particulars 

Figs.  447  448. 


will  be  given  in  the  succeeding  section ;  the  tool  is  then  fixed  in  the 
vice,  and  the  die-stock  is  handed  round,  as  in  cutting  an  ordinary 
screw.  When  Fig.  448  is  used  for  cutting  up  screw  tools,  or  the 
chasing-tools  for  the  use  of  the  turning  lathe,  the  cutter  is  then 
called  a  hob,  or  a  screw-tool  cutter,  and  its  diameter  is  usually 
greater ;  it  is  now  mounted  to  revolve  in  the  lathe,  and  the  screw 
tool  to  be  cut  is  laid  on  the  rest  as  in  the  process  of  turning,  and  is 
pressed  forcibly  against  the  cutter.  Another  method  is  proposed : 
the  inside  screw  tool  is  laid  in  a  lateral  groove  in  a  cylindrical  piece 
of  iron,  and  the  tool  and  cylinder  are  cut  up  with  the  die-stocks  as 
a  common  screw ;  by  which  mode  the  inside  screw  tool  obviously 
becomes  the  exact  counterpart  of  the  hollow  thread  of  that  particular 
diameter. 

Fig.  448  is  also  used  as  a  worm-wheel  cutter,  that  is,  for  cutting 
or  for  finishing  the  hollow  screw- form  teeth,  of  those  wheels  which 
are  moved  by  a  tangent  screw ;  as  in  the  dividing-engine  for  cir- 
cular lines,  and  many  other  cases  in  ordinary  mechanism.  The 
worm-wheel  cutter  is  frequently  set  to  revolve  in  the  lathe",  and  the 
wheel  is  mounted  on  a  temporary  axis  so  as  to  admit  of  its  being 
carried  round  horizontally  by  the  cutter ;  sometimes  the  wheel  and 
cutter  are  connected  by  gear. 

The  contact  of  the  ordinary  tangent  screw  with  the  worm-wheel, 
resembles  that  of  the  tangent  to  the  circle,  whence  the  name ;  but 
Hindley,  of  York,  made  the  screw  of  his  dividing  engine  to  touch 
15  threads  of  the  wheel  perfectly,  by  giving  the  screw  a  curved 
section  derived  from  the  edge  of  the  wheel,  and  smallest  in  the 
middle. 

In  cutting  the  metal  screw,  or  the  bolt,  the  tools  are  required  to 
be  the  converse  of  the  tap,  as  they  must  have  internal  instead  of 
external  threads,  but  the  radial  notches  are  essential  alike  in  each. 
For  small  works,  the  internal  threads  are  made  of  fixed  sizes  and 
in  thin  plates  of  steel;  such  are  called  screw  plates;  for  larger  works, 
the  internal  threads  are  cut  upon  the  edges  of  two  or  three  detached 
pieces  of  steel,  called  dies ;  these  are  fitted  into  grooves  within  die- 
stocks,  and  various  other  contrivances  which  admit  of  the  approach 


428  THE   PEACTICAL   METAL- WOEKER  S  ASSISTANT. 

of -the  screwed  dies,  so  that  they  may  be  applied  to  the  decreasing 
diameter  of  the  screw,  from  its  commencement  to  the  completion. 

The  thickness  of  the  screw  plate  is  in  general  from  about  two- 
thirds  to  the  full  diameter  of  the  screw,  and  mostly  several  holes 
are  made  in  the  same  plate ;  from  two  to  six  holes  are  intended  for 
one  thread,  and  are  accordingly  distinguished  into  separate  groups 
by  little  marks,  as  in  Fig.  449.  The  serrating  of  the  edges  is  some- 
times done  by  making  two  or  three  small  holes  and  connecting 
them  by  the  lateral  cuts  of  a  thin  saw,  as  in  Fig.  450.  The  notches 
alone  are  sometimes  made,  and  when  the  holes  are  arranged  as  in 
Fig.  451,  should  the  screw  be  broken  short  off  by  accident,  it  may 
be  cut  in  two  with  a  thin  saw,  and  thus  removed  from  the  plate. 

In  making  small  screws,  the  wire  is  fixed  in  the  hand-vice,  tap- 
ered off  with  a  file,  and  generally  filed  to  an  obtuse  point ;  then, 
after  being  moistened  with  oil,  it  is  screwed  into  the  one  or  several 
holes  in  the  screw  plate,  which  is  held  in  the  left  hand.  At  other 
times,  the  work  fixed  in  the  lathe  is  turned  or  filed  into  form,  and 
the  plate  is  held  in  the  right  hand ;  but  the  force  then  applied  is 
less  easily  appreciated.  The  harp-makers  and  some  others,  attach 
a  screw  plate  with  a  single  hole  to  the  sliding  cylinder  of  the  popit- 
head. 

Figs.  449  450  451. 


The  screw  plate  is  sometimes  used  for  common  screws  as  large 
as  from  half  to  three-quarters  of  an  inch  diameter ;  such  screws  are 
fixed  in  the  tail  vice,  and  the  screw  plate  is  made  from  about  15  to 
30  inches  long,  and  with  two  handles ;  the  holes  are  then  made  of 
different  diameters,  by  means  of  a  taper  tap,  so  as  to  form  the  thread 
by  two,  three,  or  more  successive  cuts,  and  the  screw  should  be 
entered  from  the  large  side  of  the  taper  hole.  It  is;  however,  very 
advisable  to  u^e  the  diestocks,  in  preference  to  the  screw  plates,  for 
all  screws  exceeding  about  one-sixteenth  of  an  inch  diameter, 
although  the  unvarying  diameter  of  the  screw  plate  has  the  advan- 
tage of  regulating  the  equal  size  of  a  number  of  screws,  and  as 
such,  is  occasionally  used  to  follow  the  diestocks,  by  way  of  a  gage 
for  size. 

The  diestock,  in  common  with  other  general  tools,  has  received 
a  great  many  modifications  that  it  would  be  useless  to  trace  in 
greater  detail,  than  so  far  as  respects  the  varieties  in  common  use, 
or  those  which  introduce  any  peculiarity  of  action  in  the  cutting 
edges.  A  notion  of  the  early  contrivances  for  cutting  metal  screws 


SCRE\V-CUTTIXG   TOOLS. 


429 


will  be  gathered  from  the  figures  452  to  455,  which  are  copied 
half-size  from  "Leupold's  Theatrum  Machinarum  Generale,  1724." 
For  instance,  Fig.  452  is  the  screw  plate  in  two,  and  jointed  to- 
gether like  a  common  rule ;  the  inner  edges  are  cut  with  threads, 
the  larger  of  which  is  judiciously  placed  near  the  joint,  that  it  may 
be  more  forcibly  compressed ;  there  is  a  guide  a,  a,  to  prevent  the 
lateral  displacement  of  the  edges,  which  would  be  fatal  to  the  action. 
Similar  instruments  are  still  used,  but  more  generally  for  screws 
made  in  the  turning  lathe. 


Figs.  452 


453 


454 


455. 

In  one  of  these  tools,  the  frame  or  stock  is  made  exactly  like  a 
pair  of  flat  pliers,  but  with  loose  dies  cut  for  either  one  or  two  sizes 
of  threads.  Plier  diestocks  are  also  made  in  the  form  of  common 
nut-crackers,  or  in  fact,  much  like  Fig.  452,  if  we  consider  it  to 
have  handles  proceeding  from  a  a,  to  extend  the  tool  to  about  two 
or  three  times  its  length  ;  the  guide  a  a  is  retained,  and  removable 
dies  are  added,  instead  of  the  threads  being  cut  in  the  sides  of  the 
instrument. 

In  general,  however,  the  two  dies  are  closed  together  in  a  straight 
line,  instead  of  the  arc  of  a  circle :  one  primitive  method,  Fig.  455, 
extracted  from  the  work  referred  to,  has  been  thus  remodeled ;  the 
dies  are  inserted  in  rectangular  taper  holes,  in  the  ends  of  two  long 
levers,  which  latter  are  connected  by  two  cylindrical  pins,  care- 
fully fitted  into  holes  made  through  tne  levers,  and  the  ends  of  the 
pins  are  screwed  aud  provided  with  nuts,  which  serve  more  effect- 
ually to  compress  the  dies  than  the  square  rings  represented  in 
Fig.  455. 

The  diestock  in  its  most  general  form  has  a  central  rectangular 
aperture,  within  which  the  dies  are  fitted,  so  as  to  admit  of  compres- 
sion by  one  central  screw;  the  kinds  most  in  use  being  distin- 
guished as  the  double  chamfered  diestocks,  Figs.  456  and  457 ;  and  the 
single  chamfered  diestock,  Figs.  459  and  460,  the  handles  of  which 
are  partly  shown  by  dotted  lines.  In  the  former,  the  aperture  is 
about  as  long  as  three  of  the  dies ;  about  one-third  of  the  length  of 
the  chamfer  is  filed  away  at  the  end,  for  the  removal  of  the  dies 


430 


THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 


laterally,  and  one  at  a  time.  In  the  single  chamfered  diestock  460, 
which  is  preferable  for  large  threads,  the  aperture  but  little  exceeds 
the  length  of  two  dies,  and  these  are  removed  by  first  taking  off  the 
side  plate  b  a,  which  is  either  attached  by  its  chamfered  edges  as  a 
slide,  or  else  by  four  screws ;  these,  when  loosened,  allow,  the  plate 
to  be  slid  endways,  and  it  will  be  then  disengaged,  as  the  screws 
will  leave  the  grooves  at  a,  and  the  screw  heads  will  pass  through 
the  holes  at  b. 


Sometimes  dies  of  the  section  of  Fig.  458  are  applied  after  the 
manner  of  457,  and  occasionally  the  rectangular  aperture  of  Fig. 
460  is  made  parallel  on  its  inner  edges,  and  without  the  side  plate 
b  a ;  the  dies  are  then  retained  by  steel  plates  either  riveted  or 
screwed  to  the  diestock,  as  represented  in  Fig.  461,  or  else  by  two 
steel  pins  buried  half-way  in  the  sides  of  the  stock,  and  the  re- 
maining half  in  the  die,  as  shown  in  Fig.  462.  These  variations 
are  of  little  moment,  as  are  also  those  concerning  the  general  form 
of  the  stock  :  for  instance,  whether  or  not  the  handles  proceed  in 
the  directions  shown  (the  one  handle  being  occasionally  a  con- 
tinuation of  the  pressure  screw),  or  whether  the  handles  are  placed 
as  in  the  dotted  position  t.  In  small  diestocks,  a  short  stud  or 
handle  is  occasionally  attached  at  right  angles  to  the  extremity, 
that  the  diestock  may  be  moved  like  a  winch  handle ;  and  some- 
times graduations  are  made  upon  the  pressure  screw,  to  denote  the 
extent  to  which  the  dies  are  closed.  These  and  other  differences 
are  matters  comparatively  unimportant,  as  the  accurate  fitting  of 
the  dies,  and  their  exact  forms,  should  receive  the  principal  atten- 
tion. 

In  general  only  two  dies  are  used,  the  inner  surface  of  each  of 


SCREW-CUTTING  TOOLS.  431 

which  includes  from  the  third  to  nearly  the  half  of  a  circle,  and  a 
notch  is  made  at  the  central  part  of  each  die,  so  that  the  pair  of 
dies  present  four  arcs,  and  eight  series  of  cutting  points  or  edges ; 
four  of  which  operate  when  the  dies  are  moved  in  the  one  direc- 
tion, and  the  other  four  when  the  motion  is  reversed ;  that  is  when 
the  curves  of  the  die  and  screw  are  alike. 

The  formation  of  these  parts  has  given  rise  to  much  investigation 
and  experiment,  as  the  two  principal  points  aimed  at  require  di- 
rectly opposite  circumstances.  For  instance,  the  narrower  the  edges 
of  the  dies,  or  the  less  of  the  circle  they  contain,  the  more  easily 
they  penetrate,  the  more  quickly  they  cut,  and  the  less  they  com- 
press the  screw  by  surface  friction  or  squeezing,  which  last  tends 
to  elongate  the  screw  beyond  its  assigned  length.  But,  on  the 
other  hand,  the  broader  the  edges*  of  the  dies,  or  the  more  of  the 
circle  they  contain,  the  more  exactly  do  they  retain  the  true  helical 
form  and  the  general  truth  of  the  screw. 

The  action  of  screw-cutting  dies  is  rendered  still  more  difficult, 
because  in  general  one  pair  of  dies,  the  curvatures  and  angles  of 
which  admit  of  no  change,  are  employed  in  the  production  of  a 
screw,  the  dimensions  of  which  during  its  gradual  transit  from  the 
smooth  cylinder  to  the  finished  screw  continually  change. 

For  instance,  the  thread  of  a  screw  necessarily  passes  two  mag- 
nitudes, namely,  the  top  and  bottom  of  the  groove,  and  also  two 
angles  at  these  respective  diameters,  as  represented  by  the  dotted 
lines  in  the  diagrams,  Figs.  463,  465,  and  467  (which  are  drawn 
with  straight  instead  of  curved  lines).  The  angles  are  nearly  in 
the  inverse  proportion  of  the  diameters ;  or  if  the  bottom  were 
half  the  diameter  of  the  top  of  the  thread,  the  angle  at  the  bottom 
would  be  nearly  twice  that  at  the  top. 

The  figures  show  the  original  taps,  master  taps,  or  cutters,  from 
which  the  dies,  Figs.  464,  466,  and  468,  are  respectively  made ; 
and  in  each  of  the  three  diagrams  the  dies  a  are  supposed  to  be  in 
the  act  of  commencing,  and  the  dies  b  in  finishing,  a  screw  of  the 
same  diameter  throughout  as  that  in  Fig.  463. 

Of  course  the  circumstances  become  the  more  perplexing  the 
greater  the  depth  of  the  thread,  whereas  in  shallow  threads  the 
interference  may  be  safely  overlooked.  As  the  dies  cannot  have 
both  diameters  of  the  screw,  it  becomes  needful  to  adopt  that  cur- 
vature which  is  least  open  to  objection.  If,  as  in  Fig.  464,  the 
curved  edges  of  the  dies  a  and  b  have  the  same  radii  as  the  finished 
screw,  in  the  commencement,  or  at  a,  the  die  will  only  touch  at  the 
corners,  and  the  curved  edges  being  almost  or  quite  out  of  contact, 
there  will  be  scarcely  any  guidance  from  which  to  get  the  lead  or 
first  direction  of  the  helix,  and  the  dies  will  be  likely  to  cut  false 
screws,  or  else  parallel  grooves  or  rings.  In  addition  to  this,  the 
curved  edges  present,  at  the  commencement,  a  greater  angle  than 
that  proper  for  the  top  of  .the  screw ;  but  at  the  completion  of  the 
screw,  or  at  b,  the  die  and  screw  will  be  exact  counterparts,  and 
will  be  therefore  perfectly  suitable  to  each  other. 


432  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

If,  as  in  Fig.  468,  the  inner  curvature  of  the  dies  a  and  b  be  the 
same  as  in  the  blank  cylinder,  a  will  exactly  agree  both  in  diame- 


Figs.  463 

SMALL  MASTER  TAP. 

Same  diameter  at  Screw. 


465 

MEDIUM  MASTER  TAP. 
One  depth  larger  than  Screw. 


467 

LARGE  MASTER  TAP. 
Two  deptht  larger  than  Screw. 


466 


468. 


ter  and  angle  at  the  commencement  of  the  screw,  but  at  the  con- 
clusion, or  as  at  b,  each  will  be  too  great,  and  the  die  and  screw  will 
be  far  from  counterparts,  and  therefore  ill  adapted  to  each  other. 

The  most  proper  way  of  solving  the  difficulty  in  dies  made  in 
two  parts,  is  by  having  two  pairs  of  dies,  such  as  468  and  464, 
and  which  is  occasionally  done  in  very  deep  threads,  see  Figs.  432 
and  433.  But  it  is  more  usual  to  pursue  a  medium  course,  and  to 
make  the  original  tap  or  cutter,  Fig.  465,  used  in  cutting  the  dies, 
not  of  the  same  diameter  as  the  bolt,  as  in  Figs.  463  and  464,  not 
to  exceed  the  diameter  of  the  bolt  by  twice  the  depth  of  the  thread, 
as  in  Figs.  467  and  468,  but  with  only  one  depth  beyond  the  exact 
size,  or  half-way  between  the  extremes  as  in  Figs.  465  and  466,  in 
which  latter  it  is  seen  the  contact,  although  not  quite  perfect  either 
at  a  or  b,  is  sufficiently  near  at  each  for  general  practice. 

The  obvious  effect  of  different  diameters  between  the  die  and 
screw  must  be  a  falsity  of  contact  between  the  surfaces  and  angles 
of  the  dies  ;  thus  in  464  the  whole  of  the  cutting  falls  upon  e,  the 
external  angles,  until  the  completion  of  the  screw  in  b,  when  the 
action  is  rather  compressed  than  cutting.  In  Fig.  468  the  first  act 
is  that  of  compressing,  and  all  the  work  is  soon  thrown  on  i,  the 
internal  angles  of  the  die,  which  become  gradually  more  pene- 
trative, but  eventually  too  much  so,  being  in  all  respects  the  reverse 
of  the  former.  In  the  medium  and  most  common  example,  Fig. 
466,  the  cut  falls  at  first  upon  the  external  angles  e,  it  gradually 
dies  away,  and  it  is  during  the  brief  transition  of  the  cut  from  the 
external  to  the  internal  angles  i,  that  is,  when  the  screw  is  exactly 
half-formed,  that  the  compression  principally  occurs. 

The  compression  or  squeezing  is  apt  to  enlarge  the  diameter  of 
the  'screw  (literally  by  swaging  up  the  metal),  and  also  to  elongate 


SCREW-CUTTING  TOOLS. 


433 


it  beyond  its  assigned  length,  and  that  unequally  at  different  parts. 
Sometimes  the  compression  of  the  dies  makes  the  screw  so  much 
coarser  than  its  intended  pilch  that  the  screw  refuses  to  pass  through 
a  deep  hole  cut  with  the  appropriate  tap.  Not  only  may  the  total 
increase  in  length  be  occasionally  detected  by  a  common  rule,  but 
the  differences  between  twenty  or  thirty  threads,  measured  at  va- 
rious parts  with  fine-pointed  compasses,  are  often  plainly  visible. 

Other  and  vastly  superior  modes  for  the  formation  of  long  screws, 
or  those  requiring  any  very  exact  number  of  threads  in  each  inch 
or  foot  of  their  length,  will  be  shortly  explained.  Yet  notwith- 
standing the  interferences  which  deprive  the  diestocks  of  the 
refined  perfection  of  these  other  methods,  they  are  a  most  invalu- 
able and  proper  instrument  for  their  intended  use  ;  and  the  dis- 
agreement of  curvature  and  angle  is  more  or  less  remedied  in  prac- 
tice, by  reducing  the  circular  part  of  the  dies  in  various  ways;  and 
also  in  some  instances,  by  the  partial  separation  of  the  guiding  from 
the  cutting  action. 

The  most  usual  form  of  dies  is  shown  in  Fig.  469,  but  if  every 
measure  be  taken  at  the  mean,  as  in  Fig.  470,  the  tool  possesses  a 
fair,  average,  serviceable  quality;  that  is,  the  dies  should  be  cut 
over  an  original  tap  of  medium  dimensions,  namely  one  depth 
larger  than  the  screw,  such  as  Fig.  465  ;  the  curved  surface  should 
be  halved,  making  the  spaces  and  curves  as  nearly  equal  as  may 
be  ;  and  the  edges  should  be  radial.  Fig.  471,  nearly  transcribed 
from  Leupold's  figure,  453,  has  been  also  used,  but  it  appears  as  if 
too  much  of  the  curve  were  then  removed. 

Sometimes  the  one  die  is  only  used  for  guiding,  and  the  other 
only  for  cutting:  thus  a,  Fig.  472,  is  cut  over  two  different  diameters 
of  master  taps,  which  gives  it  an  elliptical  form.  A  large  master 
tap,  Fig.  467,  is  first  used  for  cutting  the  pair  bf  dies  ;  this  leaves 
the  large  parts  of  the  curve  in  a  ;  the  dies  are  subsequently  cut 
over  a  small  master  tap,  463. 


Figs.  469        470 


471 


472 


473. 


In  beginning  the  screw,  the  die  a,  serves  as  a  bed  with  guiding 
edges ;  these  indent  without  cutting,  and  also  agree  at  the  first 
start,  with  the  full  diameter  of  the  bolt ;  with  the  gradual  reduc- 
tion of  the  bolt,  it  sinks  down  to  the  bottom  of  a,  which  continually 
presents  an  angular  ridge,  nearly  agreeing  in  diameter,  and  there- 
fore in  angle  with  the  nascent  screw.  The  inconveniences  of  the 
dies,  Fig.  472,  are,  that  they  require  a  large  and  a  small  master  tap 
28 


434 


THE   PEACTICAL   METAL-WORKER'S  ASSISTANT. 


for  the  formation  of  every  different  sized  pair  of  dies,  and  which 
latter  are  rather  troublesome  to  repair.  The  dies  also  present  more 
friction  than  most  others,  apparently  from  the  screw  becoming 
wedged  within  the  angular  sides  of  the  die  a, 

In  Fig.  473,  the  dies  are  first  cut  over  a  small  master  tap,  Fig. 
464,  the  threads  are  then  partially  filed  or  turned  out  of  b,  to  fit  the 
blank  cylinder ;  which  therefore  rests  at  the  commencement  upon 
blunt  triangular,  curved  surfaces,  instead  of  upon  keen  edges ;  and 
as  the  screw  is  cut  up,  its  thread  gradually  descends  into  the  por- 
tions of  the  thread  in  b,  which  are  not  obliterated.  About  one- 
third  of  the  thread  is  turned  out  from  each  side  of  the  cutting  die 
a,  leaving  only  two  or  three  threads  in  the  centre,  as  shown  in  the 
last  view ;  and  the  surface  of  this  die  is  left  flat,  that  it  may  be 
ground  up  afresh  when  blunted,  and  which  is  also  done  with  other 
dies  having  plane  surfaces. 

Mr.  William  Ryan  and  Mr.  Patrick  Mullen  have  each  proposed 
to  assist  the  action  of  dies  for  large  screws,  by  means  of  cutters ; 
their  plans  will  be  sufficiently  explained  by  the  diagrams,  Figs. 
474  and  475.  This  mode  to  large  screws  of  square  threads  was 
applied  for  gun  carriages ;  the  dies  were  cut  very  shallow,  say  one- 
third  of  the  full  depth,  and  they  were  serrated  on  their  inner  faces 
to  act  like  saws  or  files.  The  dies  were  used  to  cut  up  the  com- 
mencement of  the  thread,  but  when  it  filled  the  shallow  dies, 
their  future  office  was  not  to  cut,  but  only  to  guide  the  ascent  and 
descent  of  the  stocks,  by  the  smooth  surfaces  of  the  dies  rubbing 
upon  the  top  of  the  square  thread.  The  remaining  portion  of  the 
screw  was  afterwards  ploughed  out  by  a  cutter  like  a  turning  tool, 
the  cutter  being  inserted  in  a  hole  in  the  one  die,  and  advanced 
by  a  set  screw,  somewhat  after  the  manner  represented  in  the 
figures  474  and  475. 


Figs.  474 


478 


475 


Mullen  employed  a  similar  method  for  angular  thread  screws, 
and  the  cutter  was  placed  within  a  small  frame  fixed  to  the  one 
die.  The  screw  bolt  was  commenced  with  the  pair  of  dies  which 
were  closed  by  the  set  screw  a,  474,  the  cutter  being  then  out 


SCREW-CUTTING  TOOLS. 


435 


of  action.  When  the  cutter  was  set  to  work  by  its  adjusting 
screw  b,  it  was  advanced  a  little  beyond  the  face  of  the  die,  and 
not  afterwards  moved ;  but  the  advance  of  a  closed  the  dies  upon 
the  decreasing  diameter  of  the  screw,  the  cutter  always  continuing 
prominent  and  doing  the  principal  share  of  the  work. 

Figure  476  is  the  plan,  and  477  the  side  elevation,  of  an  old 
although  imperfect  expedient,  for  producing  a  left-handed  screw 
from-  a  right-handed  tap.  It  will  be  remembered  the  right  and 
left-hand  screws  only  differ  in  the  direction  of  the  angle,  the  thread 
of  the  one  coils  to  the  right,  of  the  other  to  the  left  hand ;  and  on 
comparing  a  corresponding  tap  and  die,  the  inclinations  of  the  ex- 
ternal curve  of  the  one,  and  the  internal  curve  of  the  other  neces- 
sarily differ  in  like  manner  as  to  direction.  The  mode  employed, 
therefore,  is  to  carry  a  right-hand  tap  around  the  screw  to  be  cut ; 
the  temporary  screw-cutter  possesses  the  same  interval  or  thread  as 
before,  but  the  cutting  angles  of  the  tap,  having  the  reverse  direc- 
tion of  those  of  the  die,  the  screw  becomes  left-handed. 

The  one  die  in  476  and  477  is  merely  a  blank  piece  of  brass  or 
iron  without  any  grooves,  the  other  is  a  brass  die  in  which  the  tap 
is  fixed ;  as  may  be  expected,  the  thread  produced  is  not  very  per- 
fect, but  in  the  absence  of  better  means,  this  mode  is  available  as 
the  germ  for  the  production  of  a  set  of  left-hand  taps  and  dies. 
Figs.  478  and  479  represent  a  different  mode  of  originating  a  left- 
handed  screw,  proposed  by  Mr.  Walsh ;  the  tool  is  to  be  a  small 
piece  of  a  right-handed  screw,  which  is  hardened  and  mounted  in 
a  frame  like  an  ordinary  milling  or  nurling  tool,  and  intended  to 
act  by  pressure  alone ;  the  diameter  of  the  tool  and  cylinder  should 
be  alike. 

The  screw  stock  represented  in  Fig.  480:  three  narrow  dies 


Figs.  480 


482. 


were  fitted  in  three  equidistant  radial  grooves  in  the  stock,  the 
ends  of  the  dies  came  in  contact  with  an  exterior  ring,  having  on 
its  inner  edge  three  spiral  curves  (equivalent  to  three  inclined 
planes),  and  on  its  outer  surface  a  series  of  teeth  into  which  worked 


436  THE   PRACTICAL  METAL-WORKER'S   ASSISTANT. 

a  tangent  screw,  so  that  on  turning  the  ring  by  the  screw,  the 
three  dies  were  simultaneously  and  equally  advanced  towards  the 
centre. 

These  screw  stocks  were  found  to  cut  very  rapidly,  as  every  cir- 
cumstance was  favorable  to  that  action.  For  instance,  on  the 
principle  of  the  triangular  bearing,  all  the  three  dies  were  con- 
stantly at  work ;  the  original  tap  being  slightly  taper,  every  thread 
in  the  length  of  the  die  was  performing  its  part  of  the  work,  the 
same  as  in  a  taper  tap,  every  thread  of  which  removes  its  shaving 
or  share  of  the  material ;  and  the  dies  were  narrow,  with  radial 
edges,  which  admitted  of  being  easily  sharpened. 

The  diestock  has  been  abandoned  in  favor  of  the  screw  stock, 
which  is  represented  in  Fig.  481..  The  one  die  embraces  about 
one-third  of  the  circle,  the  two  others  much  less ;  the  latter  are 
fitted  into  grooves  which  are  not  radial,  but  lead  into  a  point  sit- 
uated near  the  circumference  of  the  screw-bolt ;  the  edges  of  the 
dies  are  slightly  hooked  or  ground  respectively  within  the  radius, 
and  they  are  simultaneously  advanced  by  the  double  wedge  and 
nut ;  the  dies  are  cut  over  a  large  original,  such  as  Fig.  467,  that 
is,  two  depths  larger  than  the  screw.  The  large  die  serves  to  line 
out  or  commence  the  screw,  and  the  two  others  act  alternately ;  the 
one  whilst  the  stock  descends  down  the  bolt,  the  other  during  its 
ascent. 

We  will  notice  but  one  more  screw  stock.  It  is  seen  that  the 
one  die  embraces  about  one-third  the  screw,  the  other  is  very  nar- 
row ;  the  peculiarity  of  this  construction  is  that  a  circular  recess 
is  first  turned  out  of  the  screw  stock,  and  a  parallel  groove  is  made 
into  the  same,  the  one  handle  of  the  stock  (which  is  shaded),  nearly 
fills  this  recess,  and  receives  the  small  die.  If  the  handle  fitted 
mathematically  true,  it  is  clear  it  would  be  immovable,  but  the 
straight  part  of  the  handle  is  narrower  than  the  width  of  the 
groove ;  when  the  stock  is  turned  round,  say  in  the  direction  from 
2  to  1,  the  first  process  is  to  rotate  the  handle  in  the  circle,  and  to 
bring  it  in  hard  contact  with  the  side  1,  this  slightly  rotates  the 
die  also,  and  the  one  corner  becomes  somewhat  more  prominent 
than  the  other.  "When  the  motion  of  the  stock  is  reversed,  the 
handle  leaves  the  side  1,  of  the  groove,  and  strikes  against  the 
other  side  2,  and  then  the  opposite  angle  of  the  die  becomes  the 
more  prominent ;  and  that  without  any  thought  or  adjustment  on 
the  part  of  the  workman,  as  the  play  of  the  handle  in  the  groove 
1,  2,  is  exactly  proportioned  to  cause  the  required  angular  change 
in  the  die. 

The  cutting  edges  of  the  die  act  exactly  like  turning  tools,  and 
therefore  they  may  very  safely  be  beveled  or  hooked  as  such ;  as 
when  they  are  not  cutting,  they  are  removed  a  little  way  out  of 
contact,  and  therefore  out  of  danger  of  being  snipped  off,  or  of 
being  blunted  by  hard  friction.  The  opposite  die  affords  during  the 
time  an  efficient  guidance  for  the  screw,  and  the  broad  die  is  ad- 
vanced^ in  the  usual  manner,  by  the  pressure  screw  made  in  con- 


SCREW-CUTTING   TOOLS. 


437 


tinuation  of  the  second  handle  of  the  diestock ;  the  dies  are  kept 
in  their  places  by  a  side  plate,  which  is  fitted  in  a  chamfered 
groove  in  the  ordinary  manner. 

There  is  less  variety  of  method  in  cutting  external  screws  with 
the  diestocks,  than  internal  screws  with  taps,  but  it  is  desirable  in 
both  cases,  to  remove  the  rough  surface  the  work  acquires  in  the 
foundry  or  forge,  in  order  to  economize  the  tools ;  and  the  best 
works  are  either  bored  or  turned  cylindrically  to  the  true  diame- 
ters corresponding  with  the  screwing  tools. 

The  bolt  to  be  screwed  is  mostly  fixed  in  the  tail  vice  vertically, 
but  sometimes  horizontally,  the  dies  are  made  to  apply  fairly,  and 
.a  little  oil  is  applied  prior  to  starting.  As  a  more  expeditious 
method  suitable  to  small  screws,  the  work  is  caused  to  revolve  in 
the  lathe,  whilst  the  diestock  is  held  in  the  hand ;  and  larger 
screws  are  sometimes  marked  or  lined  out  whilst  fixed  in  the  vice, 
the  principal  part  of  the  material  is  then  removed  with  a  chasing 
tool  or  hand-screw  tool,  and  the  screw  is  concluded  in  the  die- 
stocks.  In  cutting  up  large  screw  bolts,  two  individuals  are  re- 
quired to  work  the  screw  stocks,  and  they  walk  round  the  standing 
vice  or  screwing  clamp,  which  is  fixed  to  a  pedestal  in  the  middle 
of  the  workshop. 

For  screwing  large  numbers  of  bolts,  the  engineer  employs  the 
bolt-screwing  machine,  which  is  a  combination  of  the  ordinary  taps 
and  dies,  with  a  mandrel,  driven  by  steam-power.  In  the  machine 
the  mandrel  revolves,  traverses,  and  carries  the  bolt,  whilst  the 
dies  are  fixed  opposite  to  the  mandrel ;  or  else  the  mandrel  carries 
the  tap,  and  the  nut  to  be  screwed  is  grasped  opposite  to  it.  In 
another  machine,  the  mandrel  does  not  traverse,  it  carries  the  bolt, 
and  the  dies  are  mounted  on  a  slide ;  or  else  the  mandrel  carries 
the  nut,  and  the  tap  is  fixed  on  the  slide.  The  tap  or  die  gives  the 
traverse  in  every  case,  and  the  engine  and  strap  supply  the  muscle ; 
of  course  the  means  for  changing  the  direction  of  motion  and 
closing  the  dies,  as  in  the  hand  process,  are  also  essential. 

The  screwing  table  is  a  useful  modification  of  the  bolt  machine, 
intended  to  be  used  for  small  bolts,  and  to  be  worked  by  hand. 
The  mandrel  is  replaced  by  a  long  spindle  running  loosely  in  two 


Figs.  483 


484. 


438 


THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 


bearings ;  the  one  end  of  the  spindle  terminates  in  a  small  wheel 
with  a  winch-handle,  the  other  in  a  pair  of  jars  closed  by  a  screw. 
The  jaws  embrace  the  head  of  the  bolt,  which  is  presented  opposite 
to  dies  that  are  fixed  in  a  vertical  frame  or  stock,  and  closed  by  a 
loaded  lever  to  one  fixed  distance.  In  tapping  the  nut,  it  is  fixed 
in  the  place  before  occupied  by  the  dies,  and  the  spindle  then  used 
is  bored  up  to  receive  the  shank  of  the  tap,  which  is  fixed  by  a 
side  screw.  This  machine  insures  the  rectangular  position  of  the 
several  parts,  and  the  power  is  applied  by  the  direct  rotation  of  a 
hand  wheels. 

It  will  be  gathered  from  the  foregoing  remarks,  that  the  die- 


SCREW-CUTTING   TOOLS.  439 

stock  is  an  instrument  of  most  extensive  use,  and  it  would  indeed 
almost  appear  as  if  every  available  construction  had  been  tried, 
with  a  general  tendency  to  foster  the  cutter,  and  to  expunge  the 
surface  friction  or  rubbing  action;  by  the  excess  of  which  latter 
the  labor  of  work  is  greatly  increased,  and  risk  is  incurred  of 
stretching  the  thread. 

Figures  483  and  484  show  a  shaping  machine,  built  at  the 
Lowell  Machine  Shop,  Lowell,  Mass.  Many  of  the  machines  built 
at  the  Lowell  Machine  Shop,  were  much  improved  by  W.  B. 
Bennet.  This  shaping  and  planing  instrument  will  plane  either 
flat  or  curved  surfaces. 

The  tool  bar  is  moved  by  a  variable  crank  adjustable  to  any 
length  of  motion  not  exceeding  eight  inches.  It  has  a  self-acting 
horizontal  and  circular  feed  motion,  with  a  hand-feed  motion  for 
internal  curves. 

Figs.  485,  486  show  a  gear-cutting  machine  manufactured  at  the 
Lowell  Machine  Shop,  Lowell,  Massachusetts.  The  dividing  plate 
is  forty-eight  inches  in  diameter.  This  machine  will  cut  every 
number  of  teeth  up  to  133,  and  every  even  number  to  268,  also  272, 
276,  and  360  teeth. 

The  cutter  stock  is  so  arranged  as  to  move  either  horizontally 
or  vertically,  or  at .  any  angle,  so  as  to  cut  bevel,  spur,  and  spiral 
wheels  and  gearing. 

SCREWS  CUT  BY  HAND  IN  THE  COMMON  LATHE. — Great  num- 
bers of  screws  are  required  in  works  of  wood,  ivory  and  metal, 
that  cannot  be  cut  with  the  taps  and  dies,  or  the  other  apparatus 
hitherto  considered.  This  arises  from  the  nature  of  the  materials, 
the  weakness  of  the  forms  of  the  objects,  and  the  accidental  pro- 
portions of  the  screws,  many  of  which  are  comparatively  of  very 
large  diameter  and  inconsiderable  length.  These,  and  other  cir- 
cumstances, conspire  to  prevent  the  use  of  the  diestocks  for  objects 
such  as  the  screws  of  telescopes  and  other  slender  tubes,  those  on 
the  edges  of  disks,  rings,  boxes,  and  very  many  similar  works. 

Screws  of  this  latter  class  are  frequently  cut  in  the  lathe  with 
the  ordinary  screw  tool,  and  by  dexterity  of  hand  alone;  there  is 
little  to  be  said  in  explanation  of  the  apparatus  and  tools,  which 
then  consist  solely  of  the  lathe  with  an  ordinary  mandrel  incapable 
of  traversing  endways,  and  the  screw  tools  or  the  chasing  tools, 
with  the  addition  of  the  arm  rest. 

The  screw  tool  held  at  rest  would  make  a  series  of  rings,  because 
at  the  end  of  the  first  revolution  of  the  object,  the  points  ABC 
of  the  tool  would  fall  exactly  into  the  scratches  ABC  commenced 
respectively  by  them.  But  if,  in  its  first  revolution,  the  tool  is 
shifted  exactly  the  space  between  two  of  its  teeth,  at  the  end  of  the 
revolution,  the  point  B  of  the  tool  drops  into  the  groove  made  bv 
the  point  A,  and  so  with  all  the  others,  and  a  true  screw  is  formed, 
or  a  continuous  helical  line,  which  appears  in  steady  lateral  motion 
during  the  revolution  of  the  screw  in  the  lathe. 

It  is  likely  the  tool  will  fail  exactly  to  drop  into  the  groove,  but 


440 


THE   PEACTICAL   METAL-WORKER'S   ASSISTANT. 


if  the  difference  be  inconsiderable,  a  tolerably  good  screw  is  never- 
theless formed;  as  the  tool  being  moved  forward  as  equally  as  the 
hand  will  allow,  corrects  most  of  the  error.  But  if  the  difference 
be  great,  the  tool  finds  its  way  into  the  groove  with  an  abrupt 
break  in  the  curve ;  and  during  the  revolution  of  the  screw,  as  it 
progresses  it  also  appears  to  roll  about  sideways,  instead  of  being 
quiescent,  and  is  said  by  workmen  to  be  "  drunk :"  this  error  is 
frequently  beyond  correction. 

It  sometimes  happens  that  the  tool  is  moved  too  rapidly,  and 
that  the  point  C  drops  into  the  groove  commenced  by  A ;  in  this 
case  the  coarseness  of  the  groove  is  the  same  as  that  of  the  tool, 
but  the  inclination  is  double  that  intended,  and  the  screw  has  a 
double  thread,  or  two  distinct  helices  instead  of  one ;  the  tool  may 
pass  over  three  or  four  intervals  and  make  a  treble  or  quadruple 
thread,  but  these  are  the  results  of  design  and  skill,  rather  than  of 
accident. 

On  the  other  hand,  from  being  moved  too  slowly,  the  point  B 
of  the  tool  may  fail  to  proceed  so  far  as  the  groove  made  by  A, 
but  fall  midway  between  A  and  B ;  in  this  case  the  screw  has  half 
the  rise  or  inclination  intended,  and  the  grooves  are  as  fine  again 
as  the  tool;  other  accidental  results  may  also  occur  which  it  is 
unnecessary  to  notice. 

ON  CUTTING  SCREWS  IN  LATHES  WITH  TRAVERSING  MANDRELS. 
— One  of  the  oldest,  most  simple,  and  general  apparatus  for  cutting 
short  screws  in  the  lathe,  by  means  of  a  mechanical  guidance,  is 
the  screw- mandrel  or  travers m^-mandrel,  which  appears  to  have  been 
known  almost  as  soon  as  the  iron  mandrel  itself  was  introduced. 

Fig.  487. 


Figure  487  is  copied  from  an  old  French  mandrel  mounted  m 
a  wooden  frame,  and  with  tin  collars  cast  in  two  parts ;  the  upper 
halves  of  the  collars  are  removed  to  show  the  cylindrical  necks  of 
the  mandrel,  upon  the  shaft  of  which  are  cut  several  short  screws. 
In  ordinary  turning,  the  retaining  key  k,  which  is  shown  detached 
in  the  view  k',  prevents  the  mandrel  from  traversing,  as  its  angular 


SCREW-CUTTING  TOOLS.  441 

and  circular  ridge  enters  the  groove  in  the  mandrel ;  but  although 
not  represented,  each  thread  on  the  mandrel  is  provided  with  a 
similar  key,  except  that  their  circular  arcs  are  screw-form  instead  of 
angular.  In  screw  cutting,  Tt  is  depressed  to  leave  the  mandrel  at 
liberty ;  the  mandrel  is  advanced  slightly  forward,  and  one  of  the 
screw- keys  is  elevated  by  its  wedge  until  it  becomes  engaged  with 
its  corresponding  guide-screw,  and  now  as  the  mandrel  revolves, 
it  also  advances  or  retires  in  the  exact  path  of  the  screw  selected. 

The  modern  screw-mandrel  lathe  has  a  cast-iron  frame,  and 
hardened  steel  collars  which  are  not  divided ;  the  guide  screws  are 
fitted  as  rings  to  the  extreme  end  of  the  hardened  steel  mandrel, 
and  they  work  in  a  plate  of  brass,  which  has  six  scollops,  or  semi- 
circular screws  upon  its  edge.  When  this  mandrel  is  used  for 
plain  turning,  its  traverse  is  prevented  by  a  cap  which  extends 
over  the  portion  of  the  mandrel  protruding  through  the  collars. 

In  cutting  screws  with  either  the  old  or  modern  screw-mandrel, 
the  work  is  chucked,  and  the  tool  is  applied,  exactly  in  the  man- 
ner of  turning  a  plain  object ;  but  the  mandrel  requires  an  alter- 
nating motion  backwards  and  forwards,  somewhat  short  of  the 
length  of  the  guide  screw ;  this  is  effected  by  giving  a  swinging 
motion  or  partial  revolution  to  the  foot  wheel.  The  tool  should 
retain  its  place  with  great  steadiness,  and  it  is  therefore  often  fixed 
in  the  sliding  rest,  by  which  also  it  is  then  advanced  to  the  axis 
of  the  work  with  the  progress  of  the  external  screw ;  or  by  which 
it  is  also  removed  from  the  centre  in  cutting  an  internal  screw. 

To  cut  a  screw  exceeding  the  length  of  traverse  of  the  mandrel, 
the  screw  tool  is  first  applied  at  the  end  of  the  work,  and  when  as 
much  has  been  cut  as  the  traverse  will  admit,  the  tool  is  shifted 
the  space  of  a  few  threads  to  the  left,  and  a  further  portion  is  cut ; 
and  this  change  of  the  tool  is  repeated  until  the  screw  attains  the 
full  length  required.  When  the  tool  is  applied  by  hand,  it  readily 
assumes  its  true  position  in  the  threads ;  when  it  is  fixed  in  the 
slide  rest,  its  adjustment  requires  much  care. 

In  screwing  an  object  which  is  too  long  to  be  attached  to  the 
mandrel  by  the  chuck  alone,  its  opposite  extremity  is  sometimes 
supported  by  the  front  centre  or  popit-head ;  but  the  centre  point 
must  then  be  pressed  up  by  a  spring,  that  it  may  yield  to  the 
advance  of  the  mandrel :  this  method  will  only  serve  for  very 
slight  works,  as  the  pressure  of  the  screw-tool  is  apt  to  thrust  the 
work  out  of  the  centre.  It  is  a  much  stronger  and  more  usual  plan 
to  make  the  extremity  or  some  more  convenient  part  of  the  work 
cylindrical,  and  to  support  that  part  within  a  stationary  cylindrical 
bearing,  or  collar  plate,  which  retains  the  position  of  the  work  not- 
withstanding its  helical  motion,  and  supplies  the  needful  resistance 
against  the  tool. 

The  amateur  who  experiences  difficulty  in  cutting  screws  flying, 
of  with  the  common  mandrel  and  hand-tool  unassistedly,  will  find 
the  screw-mandrel  an  apparatus  by  far  the  most  generally  convenient 
for  those  works,  in  wood,  ivory,  and  metal  turning,  to  which  the 


442 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


screw  box  and  the  taps  and  dies  are  inapplicable ;  for  the  screw- 
mandrel  requires  but  a  very  small  change  of  apparatus,  and  what- 
ever may  be  the  diameter  of  the  work,  it  insures  perfect  copies  of 
the  guide  screws,  the  half  dozen  varieties  of  which  will  be  found 
to  present  abundant  choice  as  to  coarseness,  in  respect  to  the  ordi- 
nary purposes  of  turning. 

ON  CUTTING  SCREWS  IN  LATHES  WITH  TRAVERSING  TOOLS. — A 
great  number  of  the  engines  for  cutting  screws,  and  also  of  the 
other  shaping  and  cutting  engines  now  commonly  used,  are  clearly 
to  be  traced  to  a  remote  date,  so  far  as  their  principles  are  con- 
cerned. 

For  instance,  the  germs  of  many  of  these  cutting  machines,  in 
which  the  principles  are  well  developed,  will  be  found  in  the 
primitive  rose  engine  machinery  with  coarse  wooden  frames,  and 
arms,  shaper  plate,  cords,  pulleys,  and  weights,  described  in  the 
earliest  works  on  the  lathe,  whilst  many  are  as  distinctly  but  more 
carefully  modeled  in  metal,  in  the  tools  used  in  clock  and  watch 
making,  many  of  which  have  also  been  published. 

The  principles  of  these  machines  being  generally  few  and  simple, 
admit  of  but  little  change;  but  the  structures,  which  are  "most 
diversified,  nay,  almost  endless,  have  followed  the  degrees  of  excel- 

Fig.  488. 


lence  of  the  constructive  arts  at  the  periods  at  which  they  have 
been  severally  made,  combined  with  the  inventive  talent  of  their 
projectors.  ^ 

In  most  of  the  screw-cutting  machines  a  previously-formed 
screw  is  employed  to  give  the  traverse ;  such  are  copying  machines, 
and  will  form  the  subject  of  the  present  section;  and  a  few  other 


SCREW-CUTTING  TOOLS. 


443 


engines  serve  to  originate  screws,  by  the  direct  employment  of  an 
inclined  plane,  or  the  composition  of  a  rectilinear  and  a  circular 
motion. 

The  earliest  screw-lathe  known  to  the  author  bears  the  date  of 
1569,  and  this  curious  machine,  which  is  represented  in  Fig.  488, 
is  thus  described  by  its  inventor,  Besson:  "Esplce  de  Tour  en  nulle 
part  encore  veue  et  qui  n'est  sans  subtilite,  pour  engraver  petit  d  petit  la 
Vis  d  Ventour  de  tout  Figure  ronde  et  solide,  voire  mesmes  ovale" 

The  tool  is  traversed  alongside  the  work  by  means  of  a  guide- 
screw,  which  is  moved  simultaneously  with  the  work  to  be  operated 
upon,  by  an  arrangement  of  pulleys  and  cords  too  obvious  to  require 
explanation.  It  is  however  worthy  of  remark,  that  bad  and  im- 
perfect as  the  constructive  arrangement  is,  this  early  machine  is 
capable  of  cutting  screws  of  any  pitch,  by  the  use  of  pulleys  of 
different  diameters ;  and  right  and  left-hand  screws  at  pleasure,  by 
crossing  or  uncrossing  the  cord;  and  also  that  in  this  first  machine 
the  inventor  was  aware  that  a  screw-cutting-lathe  might  be  used 
upon  elliptical,  conical,  and  other  solids. 

The  next  illustration,  Fig.  489,  represents  a  machine  described  as 

Fig.  489. 


"A  Lathe  in  which  without  the  common  art  all  sorts  of  screws  and 
other  curved  lines  can  be  made ;"  this  was  invented  by  M.  Ghrand- 
jean  prior  to  1729.  The  constructive  details  of  this  machine, 
which  are  also  sufficiently  apparent,  are- in  some  respects  superior 
to  those  in  Besson's ;  but  the  two  are  alike  open  to  the  imperfec- 
tion due  to  the  transmissions  of  motion  by  cords ;  and  Grandjean's 
is  additionally  imperfect,  as  the  scheme  represented  will  fail  to 
produce  an  equable  traverse  of  the  mandrel  compared  with  its 
revolution,  owing  to  the  continual  change  in  the  angular  relations 
between  the  arms  of  the  bent  lever,  and  the  mandrel  and  cord 
respectively.  Sometimes  the  spiral  board  or  templet  s,  is  attached 


444  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

to  the  bent  lever  to  act  upon  the  end  of  the  mandrel ;  this  also  is 
insufficient  to  produce  a  true  screw  in  the  manner  proposed. 

Several  of  the  engines  for  cutting  screws  appear  to  be  derived 
from  those  used  for  cutting  fusees,  or  the  short  screws  of  hyperbo- 
lical section,  upon  which  the  chains  of  clocks  and  watches  are 
wound,  in  order  to  counteract  the  unequal  strength  of  the  different 
coils  of  the  spiral  springs.  The  fusee  engines,  which  are  very 
numerous,  have  in  general  a  guide-screw  from  which  the  traverse  of 
the  tool  is  derived,  and  the  illustration,  Fig.  490,  selected  from  an 
old  work  published  in  1741,  is  not  only  one  of  the  earliest,  but 
also  of  the  most  exact  of  this  kind ;  and  it  exhibits  likewise  the 
primitive  application  of  change  wheels,  for  producing  screws  of 
varied  coarseness  from  one  original. 

This  instrument  is  nearly  thus  described  by  Thiout:  "A  lathe 
which  carries  at  its  extremity  two  toothed  wheels ;  the  upper  is 
attached  to  the  arbor,  the  clamp  at  the  end  of  which  holds  the  axis 
of  the  fusee  to  be  cut,  the  opposite  extremity  is  retained  by  the 
centre;  the  fusee  and  arbor  constitute  one  piece,  and  are  turned  by 
the  winch  handle.  The  lower  wheel  is  put  in  movement  by  the 
upfer,  and  turns  the  screw  which  is  fixed  in  its  centre ;  the  nut 
can  traverse  the  entire  length  of  the  screw,  and  to  the  nut  is 
strongly  hinged  the  lever  that  holds  the  graver  or  cutter,  and 
which  is  pressed  up  by  the  hand  of  the  workman.  Several  pairs 
of  wheels  are  required,  and  the  smaller  the  size  of  that  upon  the 
mandrel  the  less  is  the  interval  between  the  threads  of  the  fusee." 

Fig.  490. 


In  the  general  construction  of  the  fusee  engine,  the  guide-screw 
and  the  fusee  are  connected  together  on  one  axis,  and  are  moved 
by  the  same  winch  handle ;  the  degree  of  fineness  of  the  thread  on 
the  fusee  is  then  determined  by  the  intervention  of  a  lever  gener- 
ally of  the  first  order ;  a  great  variety  of  constructions  have  been 
made  on  this  principle.  Three  are  described  in  Thiout's  Treatise: 
namely,  in  plates  25,  26,  and  27,  the  first  by  Regnaud  de  Chaalon. 
The  mode  of  action  will  be  more  clearly  seen  in  the  next  figure, 


SCREW-CUTTING   TOOLS. 


445 


Fig.  491. 


wherein  precisely  the  same  movements  are  applied  to  the  lathe  for 
the  purpose  of  cutting  ordinary  screws. 

The  apparatus  now  referred  to  is  that  invented  by  Mr.  Healey 
of  Dublin,  an  amateur;  it  is  universal,  or  capable  within  certain 
limits  of  cutting  all  kinds  of  screws,  either  right  or  left-handed, 
and  is  represented  in  plan  in  Fig.  491,  in  which  C  is  the  chuck 
which  carries  the  work  to  be  screwed,  and  t  is  the  tool  which  lies 
upon  r  r'  the  lathe-rest,  that  is  placed  at  right  angles  to  the  bearer, 
and  is  always  free  to  move  in  its  socket  s,  as  on  a  centre,  because 
the  binding  screw  is  either  loosened  or  removed. 

On  the  outside  of  the  chuck  C  is  cut  a  coarse  guide  screw,  which 
we  will  suppose  to  be  right-handed.  The 
nut  n  n,  which  fits  the  screw  of  the  chuck, 
is  extended  into  a  long  arm,  and  the  latter 
communicates  with  the  lathe-rest  by  the 
connecting  rod  c  c.  As  the  lathe  revolves 
backwards  and  forwards  the  arm  n  (which 
is  retained  horizontally  by  a  guide  pin  g) 
traverses  to  and  fro  as  regards  the  chuck 
and  work,  and  causes  the  lathe-rest  r  /, 
to  oscillate  in  its  socket  s.  The  distance 
s  t  being  half  s  r',  a  right-handed  screw  of 
half  the  coarseness  of  the  guide  will  be 
cut ;  or  the  tool  being  nearer  to,  and  on 
the  other  side  of,  the  centre  s,  as  in  the 
dotted  position  t',  a  finer  and  left-hand 
screw  will  be  cut. 

The  rod  c  c  may  be  attached  indiffer- 
ently to  any  part  of  n  n,  but  the  smallest 
change  of  the  relation  of  s  t  to  s  r'  would 
mar  the  correspondence  of  screws  cut  at  different  periods,  and  there- 
fore t  and  r  should  be  united  by  a  swivel-joint  capable  of  being  fixed 
at  any  part  of  the  lathe-rest  r  r'. 

The  apparatus  represented  in  plan  in  Figs.  492  and  493,  although 
it  does  not  present  the  universality  of  the  last,  is  quite  correct  in 


Figs.  492 


493. 


tar 


its  action ;  it  is  evidently  a  combination  of  the  fixed  mandrel,  and 
the  old  screw  mandrel,  Fig.  487.  Four  different  threads  are  cut  on 
the  tube  which  surrounds  the  mandrel,  and  the  connection  between 


446  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

the  guide  screw  and  the  work  is  by  the  long  bar  b  b,  which  carries 
at  the  one  end  a  piece  g  filed  to  correspond  with  the  thread,  and  at 
the  other  a  socket  in  which  is  fixed  a  screw  tool  t,  corresponding 
with  the  guide  at  the  time  employed. 

The  lathe  revolves  with  continuous  motion ;  and  the  long  bar  or 
rod  being  held  by  the  two  hands  in  the  position  shown,  the  guide  g 
and  the  tool  t  are  traversed  simultaneously  to  the  left  by  the  screw 
guide ;  and  when  the  tool  meets  the  shoulder  of  the  work  both 
hands  are  suddenly  withdrawn  and  the  bar  is  shifted  to  the  right 
for  a  repetition  of  the  cut,  and  so  on  until  the  completion  of  the 
screw.  The  guide  g  is  supported  upon  the  horizontal  plate  p, 
which  is  parallel  with  the  mandrel,  and  the  tool  t  lies  upon  the 
lathe  rest  r. 

Beneath  the  tool  is  a  screw  which  rubs  against  the  lathe  rest  r, 
and  serves  as  a  stop ;  this  makes  the  screw  cylindrical  or  conical, 
according  as  the  rest  is  placed  parallel  or  oblique.  For  the  inter- 
nal screw  the  tool  is  placed  parallel  with  the  bar,  as  in  Fig.  498  ; 
and  the  check  screw  is  applied  on  the  side  towards  the  centre 
against  a  short  bar  parallel  with  the  axis  of  the  lathe. 

None  of  the  machines  which  have  been  hitherto  described  are 
proper  for  cutting  the  accurate  screws,  of  considerable  length  or 
of  great  diameter,  required  in  the  ordinary  works  of  the  engineer ; 
but  these  are  admirably  produced  by  the  screw-cutting  lathes,  in 
which  the  traverse  of  the  tool  is  effected  by  a  long  guide-screw, 
connected  with  the  mandrel  that  carries  the  work  by  a  system  of 
change  wheels  after  the  manner  employed  a  century  back,  as  in 
Fig.  490.  The  accuracy  of  the  result  now  depends  almost  entirely 
upon  the  perfection  of  the  guide-screw,  and  which  we  will  suppose 
to  possess  very  exactly  2,  4,  5,  6,  or  some  whole  number  of  threads 
in  every  inch,  although  we  shall  for  the  present  pass  by  the  methods 
employed  in  producing  the  original  guide-screw,  which  thus  serves 
for  the  reproduction  of  those  made  through  its  agency. 

The  smaller  and  most  simple  application  of  the  system  of  change 
wheels  for  producing  screws  is  shown  in  Fig.  494.  The  work  is 
attached  to  the  mandrel  of  the  lathe  by  means  of  a  chuck,  to  which 
is  also  affixed  a  toothed-wheel  marked  M,  therefore  the  mandrel, 
the  wheel  and  the  work  partake  of  one  motion  in  common.  The 
tool  is  carried  by  the  slide-rest,  the  principal  slide  of  which  is 
placed  parallel  with  the  axis  of  the  lathe  as  in  turning  a  cylinder, 
and  upon  the  end  of  the  screw  near  the  mandrel  is  attached  a  tooth 
wheel  S,  which  is  made  to  engage  in  M,  the  wheel  carried  by  the 
mandrel. 

As  the  wheels  are  supposed  to  contain  the  same  number  of 
teeth,  they  will  revolve  in  equal  times,  or  make  continually  turn 
for  turn;  and  therefore  in  each  revolution  of  the  mandrel  and 
work,  the  tool  will  be  shifted  in  a  right  line,  a  quantity  equal  to 
one  .thread  of  the  guide-screw,  and  so  with  every  coil  throughout 
its. extent  of  motion.  Consequently  the  motion  of  the  two  axes 
being  always  equal  and  continuous,  the  screw  upon  the  work  will 


SCREW-CUTTING  TOOLS.  447 

become  an  exact  copy  of  the  guide-screw  contained  in  the  slide- 
rest,  that  is,  as  regards  the  interval  between  its  several  threads,  its 
total  length,  and  its  general  perfection. 


But  the  arrows  in  M  and  S  denote  that  adjoining  wheels  always 
travel  in  opposite  directions;  when,  therefore,  the  mandrel  and 
slide-rest  are  connected  by  only  one  pair  of  wheels,  as  in  Fig.  494, 
the  direction  of  the  copy  screw  is  the  reverse  of  that  of  the  guide. 
The  right-hand  screw  being^  far  more  generally  required  in  me- 
chanism, when  the  combination  is  limited  to  its  most  simple  form, 
of  two  wheels  only,  it  is  requisite  to  make  the  slide-rest  screw  left- 
handed,  in  order  that  the  one  pair  of  wheels  may  produce  right- 
hand  threads. 

But  a  right-hand  slide-rest  screw  may  be  employed  to  produce 
at  pleasure  both  right  and  left-hand  copies,  by  the  introduction  of 
either  one  or  two  wheels,  between  the  exterior  wheels  M  and  S, 
Fig.  494.  Thus,  one  intermediate  axis,  to  be  called  I,  would  pro- 
duce a  right-hand  thread ;  two  intermediate  axes,  1 1,  would  pro- 
duce a  left-hand  thread,  and  so  on  alternately ;  and  this  mode,  in 
addition,  allows  the  wheels  M  and  S  to  be  placed  at  any  distance 
asunder  that  circumstances  may  require. 

In  making  double  thread  screws  the  one  thread  is  first  cut,  the 
wheels  are  then  removed  out  of  contact,  and  the  mandrel  is  moved 
exactly  half  a  turn  before  their  replacement,  the  second  thread  is 
then  made.  In  treble  threads  the  mandrel  is  twice  disengaged, 
and  moved  one-third  of  a  turn  each  time,  and  so  on. 

When  the  intermediate  wheels  are  employed,  it  becomes  neces- 
sary to  build  up  from  the  bearers  some  description  of  pedestal,  or 
from  the  lathe-head  some  kind  of  bracket,  which  may  serve  to 
carry  the  axes  or  sockets  upon  which  the  intermediate  wheels  re- 
volve. These  parts  have  received  a  great  variety  of  modifica- 
tions, three  of  which  are  introduced  in  the  diagrams  Figs.  495  to 
497  ;  the  wheels  supposed  to  be  upon  the  mandrel  are  situated  on 
the  dotted  line  M  M,  and  those  upon  the  slide-rest  on  the  line  S  S. 


448 


THE   PEACTICAL   METAL-WOEKEB's   ASSISTANT. 


The  rectangular  bracket  in  Fig.  495  has  two  straight  mortises ; 
by  the  one  it  is  bolted  to  the  bearers  of  the  lathe,  and  by  the  other 
it  carries  a  pair  of  wheels,  whose  pivots  are  in  a  short  piece,  which 
may  be  fixed  at  any  height  or  angle  in  the  mortise,  so  that  one  or 
both  wheels,  1 1,  may  be  used  according  to  circumstances.  In  Fig. 
496,  the  intermediate  wheel,  or  wheels,  are  carried  by  a  radial 


497. 


arm,  which  circulates  around  the  mandrel,  and  is  fixed  to  the  lathe 
head  by  a  bolt  passed  through  the  circular  mortise.  In  Fig.  496, 
a  similar  radial  arm  is  adjustable  around  the  axis  of  the  slide-rest 
screw,  in  the  fixed  bracket. 

Sometimes  the  wheel  supposed  to  be  attached  to  the  slide-rest, 
is  carried  by  the  pedestal  or  arm,  fixed  to  the  bed  or  headstock  of 
the  lathe ;  in  order  that  a  shaft  or  spindle  may  proceed  from  the 
wheel  S,  and  be  coupled  to  the  end  of  the  slide  rest  screw,  by  a 
hollow  square  or  other  form  of  socket,  so  as  to  enable  the  rest  to 
be  placed  at  any  part  of  the  length  of  the  bearer,  and  permit  a 
screw  to  be  cut  upon  the  end  of  a  long  rod. 

The  shaft  sometimes  terminates  at  each  end  in  universal  joints, 
in  order  to  accommodate  any  trifling  want  of  parallelism  in  the 
parts ;  if,  however,  the  shaft  be  placed  only  a  few  degrees  oblique, 
the  motion  transmitted  ceases  to  be  uniform,  or  it  is  accelerated 
and  retarded  in  every  revolution,  which  is  fatal  in  screw  cutting. 

This  change  in  the.  position  of  the  slide-rest  is  also  needful  in 
cutting  a  screw  which  exceeds  the  length  the  rest  can  traverse,  as 
such  long  screws  may  then  be  made  at  two  or  more  distinct  opera- 
tions ;  before  commencing  the  second  trip  the  tool  is  adjusted  to 
drop  very  accurately  into  the  termination  of  that  portion  of  the 
screw  cut  in  the  first  trip,  which  requires  very  great  care,  in  order 
that  no  falsity  of  measurement  may  be  discernible  at  the  parts 
where  the  separate  courses  of  the  tool  have  met.  This  method  of 
proceeding  has,  however,  from  necessity  been  followed  in  produc- 
ing some  of  the  earliest  of  the  long  regulating  screws,  which  have 
served  for  the  production  of  others  by  a  method  much  less  liable 
to  accident,  namely,  when  the  cut  is  made  uninterruptedly  through- 
out the  extent  of  the  work. 


SCREW-CUTTING   TOOLS.  449 

In  the  larger  application  of  the  system  of  change-wheels,  the 
entire  bed  of  the  lathe  is  converted  into  a  long  slide-rest,  the  tool 
carriage  with  its  subsidiary  slides  for  adjusting  the  position  of  the 
tool,  then  traverses  directly  upon  the  bed ;  this  mode  has  given 
rise  to  the  name  "  traversing  or  slide-lathe,"  a  machine  which  has 
received,  and  continues  to  receive,  a  variety  of  forms  in  the  hands 
of.  different  engineers.  It  would  be  tedious  and  unnecessary  to 
attempt  the  notice  of  their  different  constructions,  which  neces- 
sarily much  resemble  each  other ;  more  especially  as  the  principles 
and  motives,  which  induce  the  several  constructions  and  practices, 
rather  than  the  precise  details  of  apparatus,  are  here  under  con- 
sideration. 

The  arrangement  for  the  change- wheels  of  a  screw-cutting  lathe 
given  in  Fig.  498,  resembles  the  mode  frequently  adopted.  The 
guide-screw  extends  through  the  middle  of  the  bed,  and  projects  at 
the  end ;  there  is  a  clasp  nut,  so  that  when  required,  the  slide-rest 
may  be  detached  from  the  screw  and  moved  independently  of  the 
same.  The  train  of  wheels  is  placed  at  the  left  extremity  of  the 
lathe ;  there  is  a  radial  arm  which  circulates 
around  the  end  of  the  main  screw,  the  arm  Fig.  498. 

has  one  or  two  straight  mortises,  in  which 
are  fixed  the  axes  of  the  intermediate  wheels, 
and  there  are  two  circular  mortises,  by  which 
the  arm  may  be  secured  to  the  lathe  bed,  in 
any  required  position,  by  its  two  binding 
screws. 

On  comparing  the  relative  facilities  for  cut- 
ting screws,  either  with  the  slide-rest  furnish- 
ed with  a  train  of  wheels,  or  with  the  travers- 
ing or  screw-cutting  lathe,  the  advantage  will 
be  found  greatly  in  favor  of  the  latter ;  for  in- 
stance : — 

With  the  slide-rest  arrangement,  Fig.  494, 
the  work  must  be  always  fixed  in  a  chuck  to  which  the  first  of 
the  change-wheels  can  be  also  attached ;  the  wheels  frequently 
prevent  the  most  favorable  position  of  the  slides  from  being 
adopted ;  and  in  cutting  hollow  screws  the  change-wheels  entirely 
prevent  the  tool  carriage  of  the  slide-rest  from  being  placed  oppo- 
site to  the  centre,  and  therefore  awkward  tools,  bent  to  the  rectan- 
gular form,  must  be  then  used.  The  slide-rest  also  requires  fre- 
quent attention  to  its  parallelism  with  the  axis  of  the  lathe,  or  the 
screws  cut  will  be  conical  instead  of  cylindrical. 

With  the  traversing  lathe,  from  the  wheels  being  at  the  back  of 
the  mandrel,  no  interference  can  possibly  arise  from  them,  and 
consequently  the  work  may  be  chucked  indiscriminately  on  any 
of  the  chucks  of  the  lathe ;  every  position  may  be  given  to  the 
slide  carrying  the  tool,  and  therefore  the  most  favorable,  or  that 
nearest  to  the  work,  may  be  always  selected,  and  the  tools  need 
not  be  crooked.  As  the  tool  carriage  traverses  at  once  on  the 
29 


450  THE   PRACTICAL    METAL- WORKER'S   ASSISTANT. 

"bearers  of  the  lathe,  the  adjustment  for  parallelism  is  always  true, 
and  the  length  of  traverse  is  greatly  extended. 

The  system  of  screw-cutting  just  explained  is  very  general  and 
practical :  for  instance,  one  long  and  perfect  guide-screw  (which 
we  will  call  the  guide},  containing  2,  4,  6,  8,  10,  or  any  precise 
number  of  threads  per  inch  having  been  obtained,  it  becomes  very 
easy  to  make  from  it  subsequent  screws,  (or  copies)  which  shalLbe 
respectively  coarser  and  finer  in  any  determined  degree.  The 
principle  is,  that  whilst  the  copy  makes  one  revolution,  the  guide 
must  make  so  much  of  one  revolution,  or  so  many,  as  shall  traverse 
the  tool  the  space  required  between  each  thread  of  the  copy ;  and 
this  is  accomplished  by  selecting  change-wheels  in  the  proportions 
of  these  quantities  of  motion,  or  in  other  words,  in  the  proportion 
required  to  exist  between  the  guide-screw  and  the  copy. 

In  explanation,  we  will  suppose  the  guide  to  have  6  threads  per 
inch,  and  that  copies  of  18,  14,  12  J,  8,  3,  2,  1,  threads  per  inch  are 
required  ;  the  two  wheels  must  be  respectively  in  the  proportions 
of  the  fractions  T6g,  T\,  -fy  £,  I,  g,  5,  i,  the  guide  being  constantly 
the  numerator.  The  numerator  also  represents  the  wheel  on  the 
mandrel,  and  the  denominator  that  on  the  guide-screw  ;  any  multi- 
ples of  these  fractions  may  be  selected  for  the  change- wheels  to 
be  employed. 

For  example,  any  multiples  of  T6g,  as  if,  £f,  f  j,  etc.,  will  pro- 
duce a  screw  of  18  threads  per  inch,  the  first  and  finest  of  the 
group;  and  any  multiples  of  f,  as,  ,!?,  l£$,  etc.,  will  produce  a 
screw  of  1  thread  per  inch,  which  is  the  last  and  coarsest  of  those 
given. 

Screws  2,  4,  or  6  times  as  fine  will  result  from  the  interposing 
a  second  pair  of  wheels,  respectively  multiples  of  £,  -]-,  |,  and  placed 
upon  one  axis. 

For  instance,  the  pair  of  wheels  f  *,  used  for  producing  a  screw 
of  18  threads  per  inch,  would,  by  the  combination  A,  produce  a 
copy  three  times  as  fine,  or  a  screw  of  54  threads  per  inch.  Fig. 

496  represents  the  wheels  referred  to  in  combination  A,  and  Fig. 

497  those  in  combination  B. 

Combination  A.  Combination  B.  Combination  C. 

M      Interm.    S  M      Interm.     S  M      Interm.    S. 

24 60  120 24  27 53 

20 72  72 20  39 107 

And  the  wheels  yV  used  for  the  screw  of  one  thread  per  inch, 
would  by  the  combination  B,  produce  a  copy  three  times  as  coarse, 
or  of  three  inches  rise.  Whatsoever  the  value  of  the  intermediate 
wheels,  whether  multiplies  of  |,  f ,  |,  etc.,  they  produce  screws  re- 
spectively of  I,  I,  },  the  pitches  of  those  screws,  which  would  be 
otherwise  obtained  by  the  two  exterior  wheels  alone ;  and  in  this 
manner  a  great  variety  of.  screws^xtending  over  a  wide  range  of 
pitch,  may  be  obtained  from  a  limited  number  of  wheels. 

For  instance,  the  apparatus  Holtzapffel  and  Co.  have  recently 


SCREW- CUTTING  TOOLS.  451 

added  to  the  slide  rest,  after  the  manner  of  Figs.  494  and  496,  has 
a  series  of  about  fifteen  wheels,  of  from  15  to  144  teeth,  employed 
with,  a  screw  of  10  threads  per  inch :  several  hundred  varieties  of 
screws  may  be  produced  by  this  apparatus,  the  finest  of  which  has 
320  threads  per  inch,  the  coarsest  measures  7£  inches  in  each  coil 
or  rise :  and  the  screws  may  be  made  right  or  left-handed,  double, 
triple,  quadruple,  or  of  any  number  of  threads.  The  finest  com- 
binations are  only  useful  for  self-acting  turning ;  those  of  medium 
coarseness  serve  for  all  the  ordinary  purposes  of  screws ;  whilst 
the  very  coarse  pitches  are  much  employed  in  ornamental  works, 
and  in  cutting  these  coarse  screws  the  motion  is  given  to  the  slide- 
rest  screw,  and  by  it  communicated  to  the  mandrel. 

The  value  of  any  combination  of  wheels  may  be  calculated  as 
vulgar  fractions,  by  multiplying  together  all  the  driving  wheels  as 
numerators,  and  all  the  driven  wheels  as  denominators,  adding  also 
the  fractional  value,  or  pitch,  of  the  guide-screw ;  thus  in  the  first 
example  A : — 

24  x  20  x  1  =       480  1 

or  reduced  to  its  lowest  terms  — . 

60  x  72  x  6  =     25920  54 

The  fraction  denotes  that  ^jth  of  an  inch  is  the  pitch  of  the  screw, 
or  the  interval  from  thread  to  thread ;  also  that  it  has  54  threads 
in  each  inch,  and  which  is  called  the  rate  of  the  screw. 

And  in  C,  the  numbers  in  which  example  were  selected  at  ran- 
dom, the  screw  would  be  found  to  possess  rather  more  than  35 
threads  per  inch. 

The  fractions  should  be  reduced  to  their  lowest  terms  before  cal- 
culation, to  avoid  the  necessity  for  multiplying  such  high  numbers. 
Thus  the  first  example  would  become  reduced  to  £  x  £  X  -J  =  «V> 
and  would  be  multiplied  by  inspection  alone,  as  the  numerators 
and  denominators  may  be  taken  crossways  if  more  convenient;  thus 
f  |  is  equal  to  £,  and  §8  is  also  equal  to  £,  fractions  which  are 
smaller  than  §  and  T65,  the  lowest  terms  respectively  of  i$  and  32; 
the  second  case  could  not  be  thus  treated,  ancl  the  whole  numbers 
must  there  be  multiplied,  as  they  will  riot  admit  of  reduction. 
Other  details  will  be  advanced,  and  tables  of  the  combinations  of 
the  change- wheels  will  be  also  given,  in  treating  of  the  practice  of 
cutting  screws. 

27  x    39    x  1      1114  1 

or  reduced  to  its  lowest  terms . 

53  x  107  x  6     39026  35T}h 

In  imitation  of  the  method  of  change- wheels,  the  slide-rest  screw 
is  sometimes  moved  by  an  arrangement  of  catgut  bands,  resem- 
bling that  represented  in  Besson's  screw-lathe,  page  442. 

One  band  proceeds  from  tJpe  pulley  on  the  mandrel  to  a  spindle 
overhead  having  two  pulleys,  and  a  second  cord  descends  from 
this  spindle  to  a  pulley  on  the  slide-rest.  This  apparatus  has  been 


452  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

applied  to  cutting  the  expanding  horn  snakes.  See  Manuel  de  Tour- 
neur,  first  edit.,  1796,  vol.  ii.,  plate  21 ;  and  second  edit.,  1816,  vol. 
ii.,  plate  16. 

The  method  offers  facility  in  cutting  screws  of  various  pitches, 
"by  changing  the  pulleys,  and  also  either  right  or  left-hand  screws, 
by  crossing  or  uncrossing  one  of  the  bands. 

The  plan  is  unexceptionable,  when  applied  for  traversing  the 
tool  slowly  for  the  purpose  of  turning  smooth  cylinders,  or  sur- 
faces (which  is  virtually  cutting  a  screw  or  spiral  of  about  100 
coils  in  the  inch);  and  in  the  absence  of  better  means,  pulleys  and 
bands  are  sometimes  used  in  matching  screws  of  unknown  or  irreg- 
ular pitches,  by  the  tedious  method  of  repeated  trials;  as  on 
slightly  reducing,  with  the  turning  tool,  the  diameter  of  either  of 
the  driving  pulleys,  the  screw  or  the  work  becomes  gradually 
finer;  and  reducing  either  of  the  driven  pulleys  makes  it  coarser ; 
but  the  mode  is  scarcely  trustworthy,  and  is  decidedly  far  inferior 
to  its  descendant,  or  the  method  of  change-wheels. 

The  screw  tools,  or  chasing  tools,  employed  in  the  traversing 
lathes  for  cutting  external  and  internal  screws,  resemble  the  fixed 
tools  generally,  except  as  regards  their  cutting  edges ;  the  follow- 
ing figures,  499  to  501,  refer  to  angular  threads,  and  502  and  503 
to  square  threads. 

Angular  screws  are  sometimes  cut  with  the  single  point,  Fig. 
499,  a  form  which  is  easily  and  correctly  made ;  the  general  angle 
of  the  point  is  about  55°  to  60°,  and  when  it  is  only  allowed  to 
cut  on  one  of  its  sides  or  bevels,  it  may  be  used  fearlessly,  as  the 
shavings  easily  curl  out  of  the  way  and  escape.  But  when  both 
sides  of  the  single  point  tool  are  allowed  to  cut,  it  requires  very  much 
more  cautious  management ;  as  in  the  latter  case,  the  duplex  shav- 
ings being  disposed  to  curl  over  opposite  ways,  they  pucker  up  as 
an  angular  film,  and  in  fine  threads  they  are  liable  to  break  the 
point  of  the  tool,  or  to  cause  it  to  dig  into,  and  tear  the  work. 
Sometimes,  also,  a  fragment  of  the  shaving  is  wedged  so  forcibly 
into  the  screw  by  the  end  of  the  tool,  that  it  can  only  be  extricated 
by  a  sharp  chisel  and  hammer. 

In  cutting  angular  screws,  it  is  very  much  more  usual  and  ex- 
peditious to  employ  screw  tools  with  many  points,  which  are  made 
in  the  lathe  by  means  of  a  revolving  cutter  or  hob,  Figs.  447  and 
448,  page  427.  Screw  tools  with  many  points,  are  always  required 
for  those  angular  threads  which  are  rounded,  at  the  top  and  bottom, 
and  which  are  thence  called  rounded  or  round  threads. 

To  the  screw  tool  for  rounded  threads  is  given  the  profile  of 
Fig.  500,  which  construction  allows  the  tool  to  be  inverted,  so  that 
the  edges  may  be  alternately  used  for  the  purpose  of  equalizing 
the  section  of  the  thread.  In  making  the  tool  500,  the  hob  (which 
is  dotted}  is  put  between  centres  in  the  traversing  lathe,  and  those 
wheels  are  applied  which  would  serve  to  cut  a  screw  of  the  same 
pitch  as  the  hob ;  the  bar  of  steel  is  then  fixed  in  the  slide-rest,  so 
that  the  dotted  line  or  the  axis  of  the  tool  intersects  the  centre  of 


SCREW-CUTTING   TOOLS. 


453 


the  hob.  The  tool  is  afterwards  hollowed  on  both  sides  with  the 
file,  to  facilitate  the  sharpening,  and  it  is  then  hardened.  In  using 
the  tool,  it  is  depressed  until  either  edge  comes  down  to  the  radius, 
proceeding  from  the  (black)  circle,  which  is  supposed  to  represent 
the  screw  to  be  cut;  the  depression  gives  the  required  penetration 
to  the  upper  angle,  and  removes  the  lower  out  of  contact. 

In  the  chasing  tool  represented  in  Fig.  501,  the  cutter,  c,  is  made 
as  a  ring  of  steel  which  is  screwed  internally  to  the  diameter  of 
the  bolt,  and  turned  externally  with  an  undercut  groove,  for  the 
small  screw  and  nut  by  which  it  is  held  in  an  iron  stock,  s,  formed 
of  a  corresponding  sweep;  for  distinctness  the  cutter  and  screw 
are  also  shown  detached.  The  centre  of  the  curvature  of  the  tool 
is  placed  a  little  below  the  centre  of  the  lathe,  to  give  the  .angle  of 


Screw  Tools  for  Angular  Threads. 
Figs.  499 


Screw  Tools  for  Square  Threads. 
502 


separation  or  penetration;  and  after  the  tool  has  been  ground  away 
in  the  act  of  being  sharpened,  it  is  raised  up,  until  its  points  touch 
a  straight-edge  applied  on  the  line  a  a  of  the  stock ;  this  denotes 
the  proper  height  of  centre,  and  also  the  angle  to  which  the  tool  is 
intended  to  be  hooked,  namely,  10  degrees :  each  ring  makes  four 
or  five  cutters,  and  one  stock  may  be  used  for  several  diameters 
of  thread. 

Angular  thread  screws  are  fitted  to  their  corresponding  nuts 
simply  by  reduction  in  diameter ;  but  square  thread  screws  require 
attention  both  as  to  diameter  and  width  of  groove,  and  are  conse- 
quently more  troublesome.  Square  thread  screws  are  in  general 
of  twice  the  pitch,  or  double  the  obliquity,  of  angular  screws  of 


454  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

the  same  diameters ;  and,  consequently,  the  interference  of  angle 
before  explained  as  concerning  the  die-stocks,  refers  with  a  two- 
fold effect  to  square  threads,  which  are  in  all  respects  much  better 
produced  in  the  screw-cutting  lathe. 

'  The  ordinary  tool  for  square  thread-screws  is  represented  in 
two  views  in  Fig.  502  ;  the  shaft  is  shouldered  down  so  as  to  ter- 
minate in  a  rectangular  part  which  is  exactly  equal  to  the  width 
of  the  groove.  In  general  the  end  alone  of  the  tool  is  required 
to  cut,  and  the  sides  are  beveled  according  to  the  angle  of  tne 
screw,  to  avoid  rubbing  against  the  sides  of  the  thread.  Tools 
which  cut  upon  the  side  alone  are  also  occasionally  used  for  ad- 
justing the  width  of  the  groove.  In  either  case  it  requires  con- 
siderable care  to  maintain  the  exact  width  and  height  of  the  tool — 
the  inclination  of  which  should  also  differ  for  every  change  of 
diameter. 

To  obviate  these  several  inconveniences,  the  author  several  years 
back  contrived  a  tool-holder,  Fig.  503,  for  carrying  small  blades 
made  exactly  rectangular.  In  height,  as  at  h,  the  blades  are  alike, 
in  width,  w,  they  are  exactly  half  the  pitch  of  the  threads,  and 
they  are  ground  upon  the  ends  alone.  The  parallel  blades  are 
clamped  in  the  rectangular  aperture  of  the  tool  socket  by  the  four 
screws  c  c ;  and  when  the  screws  s  s,  which  pass  through  the  cir- 
cular mortises  in  the  sockets,  are  loosened,  the  swivel-joint  and 
graduations  allow  the  blades  to  be  placed  at  the  particular  angle 
of  the  thread,  which  is  readily  obtained  by  calculation,  and  is 
estimated  for  the  medium  depth  of  the  thread,  or  midway  between 
the  extreme  angles  at  the  top  and  bottom. 

_  One  blade,  therefore,  serves  perfectly  for  all  screws  of  the  same 
pitch,  both  right  and  left-handed,  and  of  all  diameters.  As  the 
tool  exactly  fills  the  groove,  it  works  steadily,  and  the  width  of  the 
groove  and  the  height  of  the  centre  of  the  tool  are  also  strictly 
maintained  with  the  least  possible  trouble.  The  depth  of  the 
groove,  which  is  generally  one-sixth  more  than  its  width,  is  read 
off  with  great  facility  by  means  of  the  adjusting-screw  of  the  slide- 
rest  ;  especially  if,  as  usual,  the  screw  and  its  micrometer  agree 
with  the  decimal  division  of  the  inch. 

The  holder,  Fig.  503,  has  been  much  and  satisfactorily  used  for 
screws  from  about  20  to  2  threads  per  inch ;  but  when  the  screw 
is  coarse  and  oblique,  compared  with  its  diameter,  the  blade  is 
ground  away  to  the  dotted  line  in  h,  and  is  sometimes  beveled  on 
the  sides  almost  to  the  upper  edge,  to  suit  the  obliquity  of  the 
thread,  but  without  altering  the  extreme  width  of  the  tool. 

The  tools  for  external  screws  of  very  coarse  pitch,  are  necessa- 
rily formed  in  the  lathe  by  aid  of  the  corresponding  wheels  and  a 
revolving  cutter  bar  resembling  Fig.  415,  p.  410.  The  soft  tool  is 
fixed  in  the  slide-rest,  and  is  thereby  carried  against  the  revolving 
cutter  bar,  415,  which  has  a  straight  tool,  either  pointed  or  square 
as  the  case  may  be.  Ttie  end  of  the  screw  tool  is  thus  shaped  as 
part  of  an  external  screw,  the  counterpart  of  that  to  be  cut.  The 


SCREW-CUTTING   TOOLS.  455 

face  of  the  screw  tool  is  filed  at  right  angles  to  the  obliquity  of  the 
thread,  and  the  end  and  sides  are  slightly  beveled  for  penetration 
previously  to  its  being  hardened. 

Internal  square  threads  of  small  size  are  usually  cut  with  taps 
which  resemble  Fig.  445,  p.  424,  except  in  the  form  of  the  teeth. 
When  internal  square  threads  are  cut  in  the  lathe,  the  tool  assumevS 
the  ordinary  form  of  a  straight  bar  of  steel  with  a  rectangular 
point  standing  off  at  right  angles,  in  most  respects  like  the  com- 
mon pointed  tool  for  inside  work. 

For  very  deep  holes,  and  for  threads  of  very  considerable  ob- 
liquity, cutter  bars,  such  as  Fig.  415,  p.  410,  are  used.  The  work 
and  the  temporary  bearings  of  the  bar  are  all  immovably  fixed  for 
the  time,  and  the  bar  advances  through  the  bearings  in  virtue  of 
its  screw-thread ;  or  otherwise  a  plain  bar,  having  a  cutter  only, 
and  not  being  screwed,  may  be  mounted  between  centres  in  the 
screw  lathe,  and  the  work,  fixed  to  the  slide-rest,  may  traverse 
parallel  with  the  bar  by  aid  of  the  change- wheels.  The  cutter  bar 
in  some  cases  requires  a  ring  to  fill  out  the  space  between  itself 
and  the  hole,  to  prevent  vibration  ;  and  it  is  necessary  to  increase 
the  radial  distance  of  the  cutter  between  each  trip,  by  a  set  screw, 
or  by  slight  blows  of  a  hammer. 

Very  oblique  inside  cutters  are  turned  to  their  respective  forms 
with  a  fixed  tool,  in  a  manner  the  converse  of  that  explained 
above;  and  some  peculiarities  of  management  are  required  in 
using  them,  in  order  to  obtain  the  under-cut  form  of  the  internal 
thread. 

In  cutting  screws  in  the  turning  lathe,  the  tool  only  cuts  as  it 
traverses  in  the  one  direction;  therefore  whilst  the  cutter  is 
moved  backwards,  or  in  the  reverse  direction,  for  the  succeeding 
cut,  it  must  be  withdrawn  from  the  work.  Sometimes  the  tool  is 
traversed  backwards  by  reversing  the  motion  of  the  lathe ;  and  in 
lathes  driven  by  power,  the  back  motion  is  frequently  more  rapid 
than  the  cutting  motion,  to  expedite  the  process ;  at  other  times 
the  lathe  is  brought  to  rest,  the  nut  is  opened  as  a  hinge,  so  as  to 
become  disengaged  from  the  screw,  and  the  slide-rest  is  traversed 
backwards  by  hand,  or  by  a  pinion  movement,  and  the  nut  is  again 
closed  on  the  screw,  prior  to  the  succeeding  cut.  This  mode  an- 
swers perfectly  for  screws  of  the  same  thread  as  the  guide,  and  for 
those  of  2,  4,  6,  8  times  as  coarse  or  as  fine;  but  for  those  of  2£, 
4|,  or  any  fractional  times  the  value  of  the  guide  screw,  the  clasp 
nut  cannot  in  general  be  employed  advantageously. 

The  progressive  advance  of  the  tool  between  each  cut,  is  com- 
monly regulated  by  a  circle  of  divisions  or  a  micrometer  on  the 
slide  rest  screw,  which  should  always  correspond  with  the  decimal 
division  of  the  inch.  The  substance  of  the  shaving  may  be  pretty 
considerable  after  the  first  entry  is  made,  but  it  should  dwindle 
away  to  a  very  small  quantity,  towards  the  conclusion  of  the 
screw.  To  avoid  the  necessity  for  taxing  the  memory  with  the 
graduation  at  which  the  tool  stood  when  it  was  withdrawn  for  the 


456  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

hack  stroke,  the  author  has  been  in  the  habit  of  employing  a 
micrometer  exactly  like  that  on  the  screw,  which  is  set  to  the  same 
graduation,  and  serves  as  a  remembrancer ;  another  method  is  to 
employ  an  arm  or  stop,  which  fits  on  the  axis  of  the  screw  or 
handle  with  stiff  friction,  but  nevertheless  allows  the  tool  to  be 
shifted  the  two  or  three  divisions  required  for  each  cut. 

In  the  screw  lathe  used  by  Mr.  Koberts,  the  nut  of  the  slide- 
screw  instead  of  being  a  fixture,  is  made  with  two  tails  as  a  fork, 
which  embraces  an  eccentric  spindle ;  by  the  half  rotation  of  which 
spindle,  the  nut  together  with  the  adjusting  screw,  the  slide,  and 
the  tool,  are  shifted,  as  one  mass,  a  fixed  distance  to  and  from  the 
centre,  between  each  cut ;  so  as  first  to  withdraw  and  then  to  replace 
the  tool.  .  Whilst  the  tool  is  running  back,  the  screw  is  moved  by 
its  adjusting  screw  and  divisions,  the  minute  quantit}r  to  set  in  the 
tool  for  the  succeeding  cut,  and  the  continual  wear  upon  the  adjust- 
ing screw,  as  well  as  the  uncertainty  of  its  being  correctly  moved 
to  and  fro  by  the  individual,  are  each  avoided. 

Sometimes,  with  the  view  of  saving  the  time  lost  in  running 
back,  two  tools  are  used,  so  that  the  one  may  cut  as  the  tool  slide 
traverses  towards  the  mandrel,  the  other  in  the  contrary  direction. 
An  arrangement  for  this  purpose,  as  applied  to  the  screwing  of 
bolts  in  the  lathe,  is  shown  in  Fig.  504 ;  /  represents  the  front,  and 
b  the  back  tool,  which  are  mounted  on  the  one  slide  s  s,  and  all 
three  are  moved  as  one  piece  by  the  handle  h,  which  does  not 
require  any  micrometer. 

Fig.  504. 


In  the  first  adjustment,  the  wedge  w,  is  thrust  to  the  bottom  of 
the  corresponding  angular  notch  in  the  slide  s,  and  the  two  tools 
are  placed  in  contact  with  the  cylinder  to  be  screwed.  For  the 
first  cut,  the  wedge  is  slightly  withdrawn  to  allow  the  tool  f,  to  be 
advanced  towards  the  work ;  and  for  the  return  stroke,  the  wedge 


SCREW-CUTTING  TOOLS.  457 

is  again  shifted  under  the  observation  of  its  divisions,  and  the  slide 
5  s,  is  brought  forwards,  towards  the  workman,  up  to  the  wedge ; 
this  relieves  the  tool  f,  and  projects  b,  which  is  then  in  adjustment 
for  the  second  cut ;  and  so  on  alternately.  The  command  of  the 
two  tools  is  accurately  given  by  the  wedge,  which  is  moved  a 
small  quantity  by  its  screw  and  micrometer,  between  every  alter- 
nation of  the  pair  of  tools,  by  the  screw  h. 

In  cutting  very  long  screws,  the  same  as  in  turning  long  cylin- 
drical shafts,  the  object  becomes  so  slender,  that  the  contrivance 
called  a  backstay  is  always  required  for  supporting  the  work  in 
the  immediate  neighborhood  of  the  tool.  The  backstay  is  fixed 
to  the  slide  plate,  or  the  saddle  of  the  lathe  which  carries  the  tool, 
and  is  brought  as  near  to  the  tool  as  possible ;  sometimes  the  dies 
or  bearings  are  circular,  and  fit  around  the  screw  ;  at  other  times 
they  touch  the  same  at  two,  three  or  four  parts  of  the  circle  only. 
Some  of  the  numerous  forms  of  this  indispensable  guide  or  back- 
stay will  hereafter  be  shown. 

In  using  the  screw-lathe  with  a  backstay  for  long  screws,  it  is  a 
valuable  and  important  method,  just  at  the  conclusion,  to  employ  a 
pair  of  dies  in  the  place  usually  occupied  by  the  tool ;  as  they  are 
a  satisfactory  test  for  exact  diameter,  and  they  remove  trifling 
errors  attributable  to  veins  and  irregularities  of. the  material, 
which  the  fixed  tool  sometimes  fails  entirely  to  reduce  to  the  gen- 
eral surface.  The  tool  and  backstay  may  be  each  considered  to  be 
built  on  the  tops  of  pedestals  more  or  less  lofty,  and  therefore, 
more  susceptible  of  separation  by  elasticity,  than  the  pair  of  dies 
fixed  in  a  small  square  frame.  It  has  been  judiciously  proposed, 
in  effect,  to  link  the  backstay  and  turning  tool  together,  by  the 
employment  of  a  small  frame  carrying  a  semicircular  die  of  lignum- 
vitaB,  and  a  fixed  turning  tool,  adjusted  by  a  pressure  screw;  the 
frame  to  be  applied  either  in  the  hand  alone  or  in  the  slide  rest, 
and  to  be  inverted  so  that  the  shavings  may  fall  away  without 
clogging  the  cutter. 

VARIOUS  MODES  OF  ORIGINATING  AND  IMPROVING  SCREWS. — 
The  improvement  of  the  screw  has  given  rise  to  many  valuable 
schemes  and  modes  of  practice,  which  have  not  been  noticed  in 
the  foregoing  sections,  notwithstanding  their  collective  length. 
These  practices  indeed  could  not  consistently  have  been  placed  in 
the  former  pages  of  this  subject  because  some  of  them  must  be 
viewed  as  refinements  upon  the  general  methods,  the  earlier  notice 
of  which  would  have  been  premature ;  and  others  exhibit  various 
combinations  of  methods  pursued  by  different  eminent  individuals 
with  one  common  object,  and  are  therefore  too  important  to  be 
passed  in  silence,  notwithstanding  their  miscellaneous  nature. 

To  render  this  section  sufficiently  complete,  it  appears  needful  to 
take  a  slight  retrospective  glance  of  the  early  and  the  modern  modes 
of  originating  screws  and  screw  apparatus ;  some  account  of  the 
former  may  be  found  in  the  writings  of  Pappus,  who  lived  in  the 
fourth  century. 


458  THE   PRACTICAL   METAL- WORKER' 3  ASSISTANT. 

In  the  works  of  Pappus  Alexandrinus,  a  Greek  mathematician 
of  the  fourth  century,  are  to  be  found  practical  directions  for  making 
screws. 

The  process  is  simply  to  make  a  templet  of  thin  brass  of  the  form 
of  a  right-angled  triangle,  the  angles  of  which  are  made  in  accord- 
ance with  the  inclination  of  the  proposed  screw.  This  triangle  is 
then  to  be  wrapped  round  the  cylinder  which  is  to  be  the  desired 
screw,  and  a  spiral  line  traced  along  its  edge.  The  screw  is  sub- 
sequently to  be  excavated  along  this  line.  Minute  practical  direc- 
tions are  given  not  only  for  every  step  of  this  process,  but  also  for 
the  division,  setting  out,  and  shaping  the  teeth  of  a  worm-wheel  of 
any  required  number  of  teeth  to  suit  the  screw.  (Vide  Pappi 
Math.  Col.,  lib.  viii.  prob.  xviii.) 

The  progressive  stages  which  may  be  supposed  to  have  been 
formerly  in  pretty  general  use  for  originating  screws,  may  be  thus 
enumerated : 

1.  The  first  screw-tap  may  be  supposed  to  have  been  made  by 
the  inclined  templet,  the  file,  and  screw  tool.     It  was  imperfect  in 
all  respects,  and  not  truly  helical,  but  full  of  small  irregularities. 

2.  The  dies  formed  by  the  above  were  considerably  nearer  to 
perfection,  as  the  multitude  of  pointed  edges  of  1  being  passed 
through  everj  groove  of  the  die,  the  threads  of  the  latter  became 
more  nearly  equal  in  their  rake  or  angle,  and  also  in  their  distances 
and  form. 

3.  The  screw  cut  with  such  dies  would  much  more  resemble  a 
true  helix  than  1 ;  but  from  the  irregularities  in  the  first  tap,  the 
grooves  in  the  die  2  would  necessarily  be  wide,  and  their  sides, 
instead  of  meeting  as  a  simple  angle,  would  be  more  or  less  filled 
with  ridges,  and  3  would  become  the  exact  counterpart  of  2. 

4.  A  pointed  tool  applied  in  the  lathe  would  correct  the  form  of 
the  thread  or  groove  in  3  without  detracting  from  its  improved 
cylindrical  and  helical  character,  especially  if  the  turning  tool  were 
gradually  altered  from  the  slightly  rounded  to  the  acute  form  in 
accordance  with  the  progressive  change  of  the  screw..    The  latter 
is  occasionally  changed  end  for  end,  either  in  the  die-stocks  or  in 
the  lathe,  to  reverse  the  direction  in  which  the  tools  meet  the  work, 
and  which  reversal  tends  to  equalize  the  general  form  of  the  thread. 

5.  The  corrected  screw  4,  when  converted  into  a  master-tap, 
would  make  dies  greatly  superior  to  2 ;  it  would  also  serve  for 
cutting  up  screw  tools  ;  and  lastly, 

6.  The  dies  5  would  be  employed  for  making  the  ordinary  screws 
and  working  taps ;  and  this  completes  the  one  series  of  screwing 
apparatus. 

One  original  tap  having  been  obtained,  it  is  often  made  sub- 
servient to  the  production  of  others ;  for  example,  a  screw  tool  with 
several  points  cut  over  the  corrected  original  4  would  serve  for 
striking  in  the  lathe  other  master-taps  of  the  same  thread  but 
different  diameters.  The  process  is  so  much  facilitated  by  the  per- 
fection of  the  screw  tool  that  a  clever  workman  would  thus,  with- 


SCREW-CUTTING  TOOLS.  45£ 

out  additional  correction,  strike  master-taps  sufficiently  accurate  for 
cutting  up  other  dies  larger  or  smaller  than  4.  Sometimes  also  the 
dies  5  are  used  for  marking  out  original  taps  a  little  larger  or 
smaller  than  4. 

As  a  temporary  expedient  the  screw  tool  may  be-somewhat  spread 
at  the  forge  fire  to  make  a  tool  a  little  coarser,  or  it  may  be  upset 
for  one  a  little  finer,  and  afterwards  corrected  with  a  file ;  or  screw 
tools  may  be  made  entirely  with  the  file,  and  then  employed  for 
producing,  in  the  lathe,  master-taps  of  corresponding  degrees  of 
coarseness  and  of  all  diameters. 

These  are  in  truth  some  of  the  progressive  modes  by  which,  under 
very  careful  management,  great  numbers  of  good  useful  screwing 
apparatus  have  been  produced,  and  which  answer  perfectly  well  for 
all  the  ordinary  requirements  of  "binding"  or  "attachment11  screws; 
or  as  the  cement  by  which  the  parts  of  mechani&n  and  structures 
generally  are  firmly  united  together,  but  with  the  power  of  separa- 
tion and  reunion  at  pleasure. 

In  this  comparatively  inferior  class  of  screws  considerable  latitude 
of  proportion  may  be  allowed,  and  whether  or  not  their  pitches  or 
rates  have  any  exact  relationship  to  the  inch,  is  a  matter  of  indiffer- 
ence as  regards  their  individual  usefulness ;  but  in  superior  screws, 
or  those  which  may  be  denominated  "  regulating"  anfl  "  micrometri- 
cql"  screws,  it  does  not  alone  suffice  that  the  screw  shall  be  good  in 
general  character,  and  as  nearly  as  possible  a  true  helix ;  but  it 
must  also  bear  some  defined  proportion  to  the  standard  foot  or 
inch,  or  other  measure.  The  attainment  of  this  condition  has 
been  attempted  in  various  ways,  to  some  of  which  a  brief  allu- 
sion was  made,  and  a  few  descriptive  particulars  will  now  be 
offered. 

The  apparatus  for  cutting  original  screws  by  means  of  a  wedge 
or  inclined  plane,  appears  to  be  derived  from  the  old  fusee  engine, 
a  drawing  of  which  is  given  in  Fig.  505.  In  principle  it  is  per- 
fect, and  it  is  also  universal  within  the  narrow  limitation  of  its 
structure. 

The  drawing  is  the  half  size  of  Fig.  1,  Plate  xvii.,  of  Ferdinand 
Berthoud's  Essai  sur  L> Horlogerie,  Paris,  1763.  M.  Berthoud  says, 
"  The  instrument  is  the  most  perfect  with  which  I  am  acquainted ; 
it  is  the  invention  of  M.  Le  Lievre,  and  it  has  been  reconstructed 
and  improved  by  M.  Gideon  Duval."  The  templet  or  shaper  plate 
determines  the  hyperbolical  section  of  the  fusee.  The  modifica- 
tion, with  an  inclined  plane,  is  due  to  Hindley,  of  York. 

The  handle  h  gives  rotation  to  the  work ;  and  at  the  same  time, 
by  means  of  the  rack  r  r,  and  the  pinion  fixed  on  its  axis,  the 
handle  traverses  a  slide  which  carries  on  its  upper  surface  a  bar  i ; 
the  latter  moves  on  a  centre,  and  may  be  set  at  any  inclination 
by  the  adjusting  screw  and  divisions ;  it  is  then  fixed  oy  its  clamp- 
ing screws.  The  slide  s  carries  the  tool,  and  the  end  of  this  slide 
rests  against  the  inclined  plane  i  through  the  intervention  of  a 
saddle  or  swing  piece.  The  slide  and  tool  are  drawn  to  the  lot's 


460 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


hand  by  the  chain  which  is  coiled  round  the  barrel  b,  by  means  of 
a  spiral  spring  contained  within  it. 


Fig.  505. 


Supposing  the  bar  i  i  to  stand  square  or  at  zero,  no  motion 
would  be  impressed  on  the  tool  during  its  traverse,  which  we  will 
suppose  to  require  10  revolutions  of  the  pinion.  But  if  the  bar 
were  inclined  to  its  utmost  extent,  so  that  we  may  suppose  the  one 
end  to  project  exactly  one  inch  beyond  the  other,  in  reference  to 
the  zero  line  or  the  path  of  the  slide,  then  during  the  10  revolu- 
tions of  the  screw  the  tool  would  traverse  one  inch,  or  the  differ- 
ence between  the  ends  of  the  inclined  bar  i ;  and  it  would  thereby 
cut  a  screw  of  the  length  of  one  inch,  or  the  total  inclination  of  the 
bar,  and  containing  ten  coils  or  threads. 

But  the  inclination  of  the  bar  is  arbitrary,  and  may  be  any 
quantity  less  than  one  inch,  and  may  lean  either  to  the  right  or 
left ;  consequently  the  instrument  may  be  employed  in  cutting  all 
right  or  left-hand  screws,  not  exceeding  10  turns  in  length,  nor  measur- 
ing in  their  total  extent  above  one  inch,  or  the  maximum  inclination 
of  the  bar. 

The  principle  of  this  machine  may  be  considered  faultless ;  but 
in  action  it  will  depend  upon  several  niceties  of  construction,  par- 
ticularly the  straightness  of  the  slide  and  inclined  bar,  the  equality 
of  the  rack  and  pinion,  and  the  exact  contact  between  the  tool  slide 
and  the  inclined  plane.  These  difficulties  augment  very  rapidly 
with  the  increase  of  dimensions ;  and  probably  the  machine  made 
by  Mr.  Adam  Eeid  exclusively  for  cutting  screws,  is  as  large  as 


SCREW-CUTTING  TOOLS.  461 

can  be  safely  adopted.  The  inclined  plane  is  44  inches  long,  but 
the  work  cannot  exceed  l^ths  inch  diameter,  2£  inches  long,  or 
ten  threads  in  total  length.  The  application  of  the  inclined  plane 
to  cutting  screws  is  therefore  too  contracted  for  the  ordinary  wants 
of  the  engineer,  which  are  now  admirably  supplied  by  the  screw- 
cutting  lathes  with  guide  screws  and  change  wheels. 

The  accuracy -of  screws  has  always  been  closely  associated  with 
the  successful  performance  of  engines  for  graduating  circles  and 
right  lines,  and  the  next  examples  will  be  extracted  from  the  pub- 
lished accounts  of  the  dividing  engines  made  by  Mr.  Ramsden. 

This  eminent  individual  received  a  reward  from  the  Board  of 
Longitude,  upon  the  condition  that  he  would  furnish  for  the  benefit 
of  the  public  a  full  account  of  the  methods  of  constructing  and 
using  his  dividing  machines,  and  which  duly  appeared  in  the 
following  tracts :  "  Description  of  an  Engine  for  Dividing  Mathe- 
matical Instruments,  by  Ramsden,  4to.,  1777."  Also,  "Descrip- 
tion of  an  Engine  for  Dividing  Straight  Lines,  by  Ramsden,  4to., 
1779,  from  which  the  following  particulars  are  extracted  : 

The  circular  dividing  engine  consisted  of  a  large  wheel  moved 
by  a  tangent  screw ;  the  wheel  was  45  inches  diameter,  and  had 
2160  teeth,  so  that  six  turns  of  the  tangent  screw  moved  the  circle 
one  degree  ;  the  screw  had  a  micrometer,  and  also  a  ratchet-wheel 
of  60  teeth — therefore  one  tooth  equalled  one-tenth  of  a  minute 
of  a  degree.  The  screw  could  be  moved  a  quantity  equal  to  one 
single  tooth,  or  several  turns  and  parts,  by  means  of  a  cord  and 
treadle,  so  that  the  circular  works  attached  to  the  dividing  wheel 
could  be  readily  graduated  into  the  required  numbers  by  setting 
the  tangent  screw  to  move  the  appropriate  quantities.  The  divid- 
ing knife  or  diamond  point  always  moved  on  one  fixed  radial  line 
by  means  of  a  swing-frame. 

"In  ratching  or  cutting  the  wheel,"  says  Mr.  Ramsden,  "the 
circle  was  divided  with  the  greatest  exactness  I  was  capable  of, 
first  into  5  parts,  and  each  of  these  into  3 ;  these  parts  were  then 
bisected  4  times ;  this  divided  the  wheel  into  240  divisions,  each 
intended  to  contain  9  teeth.  The  ratching  was  commenced  at  each 
of  the  240  divisions  by  setting  the  screw  each  time  to  zero  by  its 
micrometer,  and  the  cutter  frame  to  one  of  the  great  divisions  by 
the  index ;  the  cutter  was  then  pressed  into  the  wheel  by  a  screw, 
and  the  cutting  process  was  interrupted  at  the  ninth  revolution  of 
the  screw.  It  was  resumed  at  the  next  240th  division  (or  nine 
degrees  off),  as  at  first,  and  so  on. 

This  process  was  repeated  three  times  round  the  circle,  after 
which  the  ratching  was  continued  uninterruptedly  around  the  wheel 
about  300  times ;  this  completed  the  teeth  with  satisfactory  accu- 
racy. The  tangent  screw  was  subsequently  made,  as  explained  in 
the  text. 

The  first  application  of  the  tangent  screw  and  ratchet  to  the  pur- 
poses of  graduation,  appears  to  have  been  in  the  machine  for  cut- 
ting clock  and  watch  wheels,  by  Pierre  Fardoil ;  see  plate  23  of 


462  THE   PRACTICAL   METAL-WOEKER  S   ASSISTANT. 

Thiout's  Traite  d*  Horlogerie,  etc.  Paris,  1741.  At  page  55  is 
given  a  table  of  ratchets  and  settings  for  wheels  with  from  102  to 
800  teeth. 

In  Mr.Ramsden's  description  of  his  dividing  engines  for  circles,  he 
says:  "Having  measured  the  circumference  of  the  dividing  wheel,  I 
found  it  would  require  a  screw  about  one  thread  in  a  hundred  coarser 
than  the  guide-screw."  He  goes  on  to  explain  that  the  guide-screw 
moved  a  tool  fixed  in  a  slide  carefully  fitted  on  a  triangular  bar,  an 
arrangement  equivalent  to  a  slide-rest  and  fixed  tool:  the  screw  to  be 
cut  was  placed  parallel  with  the  slide,  and  the  guide-screw  and  copy 
were  connected  by  two  change  wheels  of  198  and  200  teeth  (numbers 
in  the  proportion  required  between  the  guide  and  copy),  with  an  in- 
termediate wheel  to  make  the  threads  on  the  two  screws  in  the  same 
direction.  As  no  account  is  given  of  the  mode  in  which  the  guide- 
screw  was  itself  formed,  it  is  to  be  presumed  it  was  the  most  correct 
screw  that  could  be  obtained,  and  was  produced  by  some  of  the  means 
described  in  the  beginning  of  the  present  sections. 

Mr.  Ramsden  employed  a  more  complex  apparatus  in  originat- 
ing the  screw  of  his  dividing  engine  for  straight  lines,  which  it 
was  essential  should  contain  exactly  20  threads  in  the  inch ;  a  con- 
dition uncalled  for  in  the  circular  engine,  in  which  the  equality  of 
the  teeth  of  the  wheel  required  the  principal  degree  of  attention. 
This  second  screw-cutting  apparatus,  which  may  be  viewed  as  an 
offspring  of  the  circular  dividing  engine,  is  represented  in  plan,  in 
Fig.  509,  and  may  be  thus  briefly  explained. 

Fig.  509. 


The  guide-screw  Gr  is  turned  round  by  the  winch,  and  in  each 
revolution  moves  the  larger  tangent  wheel  one  tooth :  the  tangent 
wheel  has  a  small  central  box  <fr  pulley  p,  to  which  is  attached 
the  one  end  of  an .  elastic  slip  of  steel,  like  a  wateh-spring ;  the 
other  end  of  the  slip  is  connected  with  the  slide  s,  that  carries  the 
tool  t,  in  a  right  line  besides  the  screw  C,  which  latter  is  the  piece 
to  be  cut ;  and  C  is  connected  with  the  guide-screw  G,  by  a  bevel 
pinion  and  wheel  g,  and  c,  as  1  to  6. 


SCREW-CUTTING  TOOLS.  463 

To  proportion  the  traverse  of  the  tool  to  the  interval  or  pitch  of 
the  screw,  two  dots  were  made  on  the  slide  s,  exactly  five  inches 
asunder ;  and  in  that  space  the  screw  should  contain  100  coils,  to 
be  brought  about  by  600  turns  of  the  handle.  The  guide-screw 
was  moved  that  number  of  revolutions,  and  the  diameter  of  p  was 
reduced  by  trial,  until  the  600  turns  traversed  the  slide  exactly 
from  dot  to  dot ;  these  points  were  observed  at  the  time  through  a 
lens  placed  in  a  fixed  tube,  and  having  a  fine  silver  wire  stretched 
diametrically  across  the  same  as  an  index. 

See  "  Description  of  an  Engine  for  Dividing  Straight  Lines." 

In  the  construction  of  his  dividing  engine  for  straight  lines, 
Eamsden  very  closely  followed  his  prior  machine  for  circular 
lines,  if  we  conceive  the  wheel  spread  out  as  a  rectangular  slide. 
On  the  one  edge  of  the  main  slide  which  carried  the  work,  was  cut 
a  screw-form  rack,  with  twenty  teeth  per  inch,  which  was  moved 
by  a  short  fixed  screw  of  the  same  pitch,  by  means  of  ratchets  of 
50,  48,  or  32  teeth  respectively;  the  screw  could  be  moved  a 
quantity  equal  to  one  single  tooth,  or  to  several  turns  and  parts, 
by  means  of  a  treadle.  To  obtain  divisions  which  were  incompa- 
tible with  the  sub-division  of  the  inch  into  1000,  960  or  640  parts, 
the  respective  values  of  one  tooth,  the  scale  was  laid  on  the  slide 
at  an  angle  to  the  direction  of  motion ;  when  the  swing  frame  was 
placed  to  traverse  the  knife  at  right  angles  to  the  path  of  the  slide, 
the  graduations  were  lengthened ;  when  the  knife  was  traversed  at 
right  angles  to  the  oblique  position  of  the  scale  being  divided,  they 
were  shortened.  This  was  to  a  small  degree  equivalent  to  having 
a  screw  of  variable  length.  In  cutting  the  screw -form  teeth  of  the 
rectilinear  dividing  engine,  the  entire  length,  namely,  25.6  inches, 
was  first  divided  very  carefully  by  continual  bisection  into  spaces 
of  eight-tenths  of  an  inch,  by  hand  as  usual,  and  the  screw-cutter 
was  placed  at  zero  at  each  of  these  divisions,  pressed  into  the  edge 
of  the  slide,  and  revolved  sixteen  times ;  after  three  repetitions  at 
each  of  the  principal  spaces,  the  entire  length  was  patched  continu- 
ously until  the  teeth  were  completed. 

With  the  view  of  producing  screws  of  exact  values,  engineers 
have  employed  numerous  modifications  of  the  chain  or  band  of 
steel,  the  inclined  knife,  the  inclined  plane,  and  indeed  each  of  the 
known  methods,  which,  however,  were  remodelled  as  additions  to 
the  ordinary  turning-lathe  with  a  triangular  bar. 

Some  give  a  preference  to  the  inclined  knife,  applied  against  a 
cylinder  revolving  in  the  lathe,  by  means  of  a  slide  running  upon 
the  bar  of  the  lathe ;  which,  besides  being  very  rapid,  reduced  the 
mechanism  to  its  utmost  simplicity.  This  made  the  process  to  de- 
pend almost  alone  on  the  homogeneity  of  the  materials,  and  on  the 
relation  between  the  diameter  of  the  cylinder  and  the  inclination 
of  the  knife ;  whereas  in  a  complex  machine,  every  part  concerned 
in  the  transmission  of  motion,  such  as  each  axis,  wheel  and  slide, 
entails  its  risk  of  individual  error,  and  may  depreciate  the  accuracy 
of  the  result ;  and  to  these  sources  of  disturbance,  must  be  added 


464  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

those  due  to  change  of  temperature,  whether  arising  from  the  at- 
mosphere or  from  friction,  especially  when  different  metals  are 
concerned. 

A  rod  of  wood,  generally  of  alder  and  about  two  feet  long,  was 
put  between  the  centres,  and  reduced  to  a  cylinder  by  a  rounder 
or  witchet,  attached  to  a  slide  running  on  the  bar ;  the  slide  with 
the  inclined  knife  was  then  applied,  and  the  angle  of  the  knife  was 
gradually  varied  by  adjusting  screws,  until  several  screws  made 
in  succession,  were  found  to  agree  with  some  fixed  measure.  The 
experiment  was  then  repeated  with  the  same  angle,  upon  cylinders 
of  the  same  diameter,  of  tin,  brass,  and  other  comparatively  soft 
metals,  and  hundreds,  or  it  might  almost  be  said,  thousands  of 
screws  were  thus  made. 

From  amongst  these  screws  were  selected  those  which,  on  trial 
in  the  lathe,  were  found  to  be  most  nearly  true  in  their  angle,  or 
to  have  a  quiescent  gliding  motion ;  and  which  would  also  best 
endure  a  strict  examination  as  to  their  pitch  or  intervals,  both  with 
the  rule  and  compasses,  and  also  when  two  were  placed  side  by 
side;  and  their  respective  threads  were  compared,  as  the  divisions 
on  two  equal  scales. 

The  most  favorable  screw  having  been  selected,  it  was  employed 
as  a  guide-screw,  in  a  simple  apparatus  which  consisted  of  two 
triangular  bars  fixed  level,  parallel,  and  about  one  foot  asunder,  in 
appropriate  standards  with  two  apertures ;  the  one  bar  carried  the 
mandrel  and  popit-heads  as  in  the  ordinary  bar  lathe.  The  slide 
rest  embraced  both  bars,  and  was  traversed  thereupon  by  the 
guide-screw  placed  about  midway  between  the  bars;  the  guide 
screw  and  mandrel  were  generally  connected  by  three  wheels,  or 
else  by  two  or  four,  when  the  guide  and  copy  were  required  to 
have  the  reverse  direction.  The  mandrel  was  not  usually  driven 
by  a  pulley  and  cord ;  but  on  the  extremity  of  the  mandrel  was 
fixed  a  light  wheel,  with  one  arm  serving  as  a  winch  handle  for 
rapid  motion  in  running  back  ;  and  six  or  eight  radial  arms  (after 
the  manner  of  the  steering  wheels  of  large  vessels),  by  which  the 
mandrel  and  the  screw  were  slowly  handed  round  during  the  cut. 

In  a  subsequent  and  stronger  machine  the  bar  carrying  the  man- 
drel stood  lower  than  the  other,  to  admit  of  larger  change  wheels 
upon  it,  and  the  same  driving  gear  was  retained.  And  in  another 
structure  of  the  screw-cutting  lathe,  the  triangular  bar  was  placed 
for  the  lathe  heads  in  the  centre,  whilst  a  large  and  wide  slide- 
plate,  moving  between  chamfer  bars  attached  to  the  framing,  car- 
ried the  sliding  rest  for  the  tool ;  in  this  last  machine,  the  mandrel 
was  driven  by  steam-power,  and  the  retrograde  motion  had  about 
double  the  velocity  of  that  used  in  cutting  the  screw. 

The  relations  between  the  guide-screw  and  the  copy  were  varied 
in  all  possible  ways :  the  guide  was  changed  end  for  end,  or  dif- 
ferent parts  of  it  were  successively  used ;  sometimes,  also,  two 
guide-screws  were  yoked  together  with  three  equal  wheels,  their 
nuts  being  connected  by  a  bar  jointed  to  each,  and  the  centre  of 


SCREW-CUTTIXG  TOOLS.  '    465 

this  link  (whose  motion  thus  became  the  mean  of  that  of  the 
guides)  was  made  to  traverse  the  tool.  Steel  screws  were  also  cut, 
and  converted  into  original  taps,  from  which  dies  were  made,  to  be 
themselves  used  in  correcting  the  minor  errors,  and  render  the 
screws  in  all  respects  as  equable  as  possible.  In  fact,  every 
scheme  that  he  could  devise,  which  appeared  likely  to  benefit  the 
result,  was  carefully  tried,  in  order  to  perfect  to  the  utmost,  the 
helical  character  and  equality  of  subdivision  of  the  screw. 

The  change  of  the  thousandth  part  of  the  total  length,  was 
therefore  given  to  the  tool  as  a  supplementary  motion,  which  might 
be  added  to,  or  subtracted  from,  the  total  traverse  of  the  tool,  in 
the  mode  explained  by  the  diagram,  Fig.  507,  in  which  all  details 
of  construction  are  purposely  omitted.  The  copy  C,  and  the  guide- 
screw  G,  are  supposed  to  be  connected  by  equal  wheels  in  the 
usual  manner ;  the  guide-screw  carries  the  axis  of  the  bent  lever, 
whose  arms  are  as  10  to  1,  and  which  moves  in  a  horizontal  plane ; 
the  short  arm  carries  the  tool,  the  long  arm  is  jointed  to  a  saddle 
which  slides  upon  a  triangular  bar  i  i. 

In  point  of  fact,  the  tool  was  mounted  upon  the  upper  of  two 
longitudinal  and  parallel  slides,  which  were  collectively  traversSd 
by  the  guide-screw  G.  In  the  lower  slide  was  fixed  the  axis  or 
fulcrum  of  the  bent  lever,  the  short  arm  of  which  was-  connected 
by  a  link  with  the  upper  slide,  so  that  the  compensating  motion 
was  given  to  the  upper  slide  relatively  to  the  lower : 

Fig.  507. 


The  triangular  bar  i  i,  when  placed  exactly  parallel  with  the  path 
of  the  tool,  would  produce  no  movement  on  the  same,  and  C,  and 
G,  would  be  exactly  alike ;  but  if  i  i  were  placed  out  of  the  paral- 
lelism one  inch  in  the  whole  length,  the  tool,  during  its  traverse  to 
the  left  by  the  guide-screw  G,  would  be  moved  to  the  right  by  the 
shifting  of  the  bent  lever,  one-tenth  of  the  displacement  of  the  bur, 
or  one-tenth  of  an  inch. 

Therefore,  whilst  the  guide-screw  G,  from  being  coarser  than 
required,  moved  the  principal  slide  the  one-thousandth  part  of  the 
total  length  in  excess ;  the  bent  lever  and  inclined  straight  bar  i  i, 
pulled  back  the  upper  or  compensating  slide,  the  one-thousandth 
part,  or  the  quantity  in  excess ;  making  the  absolute  traverse  of  the 
tool  exactly  seven  feet,  or  the  length  required  for  the  new  screw  C, 
instead  of  seven  feet  and  one-sixteenth  of  an  inch,  the  length  of  G. 
To  have  lengthened  the  traverse  of  the  tool,  the  bar  1 1  must  have 
been  inclined  the  reverse  way ;  in  other  words,  the  path  of  the  tool 
30 


466  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

is  in  the  diagram  the  difference  of  the  two  motions ;  in  the  reverse 
inclination,  its  path  would  be  the  sum  of  the  two  motions,  and  i  i 
being  a  straight  line,  the  correction  would  be  evenly  distributed  at 
every  part  of  the  length. 

Other  experimentalists  preferred,  however,  the  method  of  the 
chain,  or  flexible  band,  for  traversing  the  tool  the  exact  quantity  ; 
because  the  reduction  of  a  diameter  of  the  pulley  or  drum,  afforded 
a  very  ready  means  of  adjustment  for  total  length ;  and  all  the 
wheels  of  the  mechanism  being  individually  as  perfect  as  they  could 
be  made,  a  near  approach  to  general  perfection  was  naturally  antic- 
ipated on  the  first  trial.  This  mode,  however,  is  subject  to  the 
error  introduced  by  the  elasticity  or  elongation  of  the  chain  or 
band,  and  which  is  at  the  maximum  when  the  greatest  length  of 
chain  is  uncoiled  from  the  barrel. 

About  the  year  1820,  Mr.  Clement  put  in  practice  a  peculiar 
mode  for  originating  the  guide-screw  of  his  screw-lathe,  the  steps 
of  which  plan  will  be  now  described. 

1.  He  procured  from  Scotland  some  hand-screw  tools  cut  over  a 
hob  with  concentric  grooves ;  and  to  prevent  the  ridges  or  points 
of*  the  screw  tools  from  being  cut  square  across  the  end,  the  rest 
was  inclined  to  compensate  for  the  want  of  angle  in  the  hob  or 
cutter. 

2.  A  brass  screw  was  struck  by  hand,  or  chased  with  the  tool  1. 

3.  The  screw  2,  was  fixed  at  the  back  of  a  traversing  mandrel, 
and  clipped  between  two  piec'es  of  wood  or  dies  to  serve  as  a  guide, 
whilst, 

4.  A  more  perfect  guide-screw  was  cut  with  a  fixed  tool,  and 
substituted  on  the  mandrel  for  3;  as  Mr.  Clement  considered  the 
movement  derived  from  the  opposite  sides  of  the  one  screw,  became 
the  mean  of  the  two  sides,  and  corrected  any  irregularities  of  angle, 
or  of  drunkenness. 

5.  A  large  and  a  small  master-tap  m,  Fig.  508,  were  cut  on  the 
traversing  mandrel  with  a  fixed  tool,  the  threads  were  about  an 
inch  long  and  situated  in  the  middle  of  a  shaft  eight  or  ten  inches 
long ;  the  small  master-tap  was  of  the  same  diameter  as  the  finished 
screw,  the  large  master-tap  measured  at  the  bottom  of  the  thread 
the  same  as  the  blank  cylinder  to  be  screwed.    The  master-taps  m, 
were  used  in  cutting  up  the  rectangular  dies  required  in  the  apparatus 
shown  in  Fig.  508,  and  now  to  be  described. 

6.  On  the  parallel  bed  of  a  lathe  were  fitted  two  standards  or 
collar-heads  h  h',  intended  to  receive  the  pivots  of  the  screw  to  be 
cut,  on  the  extremity  of  which  was  placed  a  winch  handle,  or  some- 
times an  intermediate  socket  was  interposed  between  the  screw  ana 
the  winch,  to  carry  the  latter  to  the  end  of  the  bed.     The  bed  had 
also  an  accurate  slide  plate  s  sf,  running  freely  upon  it,  the  slide 
plate  had  two  tails  which  passed  beside  the  head  h',  and  at  the 
other  end,  a  projection  through  which  was  made  a  transverse  rec- 
tangular mortise  for  the  dies,  the  one  end  of  the  mortise  is  shown 
by  the  removal  of  the  front  die  d,  and  the  back  die  d'  is  seen  in  its 


SCREW-CUTTING  TOOLS.  467 

proper  situation ;  one  extremity  of  each  die  was  cut  from  the  large 
master  tap  m,  and  the  other  from  the  small.  The  clamp  >or  shackle 
c  c',  was  used  to  close  the  two  dies  upon  the  screw  simultaneously ; 
it  is  shown  out  of  its  true  position  in  order  that  the  dies  and  mortise 
may  be  seen,  but  when  in  use  the  shackle  would  be  shifted  to  the 
right,  so  as  to  embrace  the  dies  d  dr.  The  plain  extremity  c'  rested 
against  the  back  die,  whilst  the  screw  c  bore  against  the  front  die, 
through  the  intervention  of  the  washer  loosely  attached  to  the 
clamp  to  save  the  teeth  from  injury ;  the  pressure  screw  c  had  a 
graduated  head  and  an  index,  to  denote  how  much  the  dies  were 
closed. 


7.  A  cylinder  about  two  feet  long,  prepared  for  the  screw,  was 
placed  between  the  heads  hhf,  and  the  large  dies,  whose  inner 
edges  were  of  the  same  diameter  as  the  cylinder,  were  closed  upon 
it  moderately  tight,  and  the  screw  was  turned  round  with  the  winch, 
to  trace  a  thread  from  end  to  end ;  this  was  repeated  a  few  times, 
the  dies  being  slightly  closed  between  each  trip. 

8.  A  screw-tool  was  next  fixed  on  the  slide  s  s',  in  a  chamfer 
slide  1 1',  with  appropriate  adjusting  screws,  so  as  to  follow  the  dies 
and  remove  a  shaving,  much  the  same  as  in  turning.     The  dies 
having  arrived  at  one  end  of  the  screw,  the  same  screw  tool  or 
a  second  tool  was  placed  on  the  opposite  side  of  the  side-plate  so 
as  to  cut  during  the  return  movement.     With  the  progress  of  the 
screw  the  screw-tool  was  applied  at  a  variety  of  distances  from  the 
pair  of  dies,  as  well  as  on  opposite  sides  of  the  screw,  so  that  the 
metal  was  cut  out  by  the  tool,  and  the  dies  were  used  almost  alone 
to  guide  the  traverse.     Of  course  the  dies  were  closed  between 
each  trip,  and  when  the  screw  was  about  half  cut  up  the  small  dies 
were  substituted  for  the  large  ones  used  at  the  commencement  of 
the  process. 

9.  The  screw  thus  made,  which  was  intended  for  a  slide-rest, 
was  found  to  be  very  uniform  in  its  thread,  and  it  was  used  for 
some  time  for  the  ordinary  purposes  of  turning.    When,  however, 
it  was  required  to  be  used  for  cutting  other  screws,  it  was  found 
objectionable  that  its  rate  was  nearly  nine,  whereas  it  was  required 
to  have  eight  threads  per  inch.    It  was  then  used  in  cutting  a  new 
guide-screw  by  means  of  a  pair  of  change  wheels  of  50  and  56 


468 


THE  PKACTICAL  METAL-WORKER'S  ASSISTANT. 


teeth,  which  upon  calculation  were  found  to  effect  the  conversion 
with  sufficient  precision. 

10.  From  9,  the  screw  of  24  inches  in  length,  one  of  8  feet  in 
length  was  obtained.  The  thread  was  cut  one-third  of  its  depth, 
with  the  wheels,  successive  portions  being  operated  upon  and  the 
tool  being  carefully  adjusted  to  the  termination  of  the  part  pre- 
viously cut.  The  general  truth  of  the  entire  length  was  given  by 

Fig.  509.  ,^' 


a  repetition  of  the  tedious  mode  of  correction  represented  in  the 
figure,  with  the  dies  and  tool  applied  upon  a  bearer  rather  exceed 
ing  the  full  length  of  the  screw. 

Fig.  510. 


Although  the  processes  7  and  8  will  produce  a  most  uniform 
screw,  Mr.  Clement  attaches  little  importance  to  the  use  of  the  dies 


SCREW-CUTTING  TOOLS. 


469 


Fig.  511. 


and  guide-frame  alone  when  several  screws  are  wanted  strictly  of 
the  same  length.  Of  some  few  thus  made  as  nearly  as  possible  under 
equal  circumstances  two  screws  were  found  very  nearly  to  agree, 
and  a  third  was  above  a  tenth  of  an  inch 
longer  in  ten  inches.  This  difference  he 
thinks  to  have  arisen  in  marking  out  the 
threads,  from  a  little  variation  in  the  fric- 
tion of  the  slide,  or  a  difference  in  the 
first  penetration  of  the  dies. 

The  friction  of  the  slide,  when  sufficient 
to  cause  any  retardation,  he  considers  to 
produce  a  constant  and  accumulative  ef- 
fect ;  first,  as  it  were,  reducing  the  screw 
of  15  threads  per  inch,  say  to  the  fineness 
of  15J,  then  acting  upon  that  of  15J,  re- 
ducing it  to  15 1,  and  so  on;  and  that  to 
such  an  extent,  as  occasionally  to  place 
the  screw  entirely  beyond  the  correctional 
process.  This  cannot  be  the  case  when 
the  thread  is  first  marked  out  with  the 
change-wheels  instead  of  the  dies. 

One  very  important  application  of  the 
screw  is  to  the  graduation  of  mathe- 
matical scales.  The  screw  is  then  em- 
ployed to  move  a  platform,  which  slides 

very  freely  and  carries  the  scale  to  be  graduated ;  and  the  swing 
frame,  for  the  knife  or  diamond  point,  is  attached  to  some  fixed 
part  of  the  framing  of  the  machine.  Supposing  the  screw  to  be 
absolutely  perfect,  and  to  have  fifty  threads  per  inch,  successive 
movements  of  fifty  revolutions  would  move  the  platform  and  grad- 
uate the  scale  exactly  into  true  inches  ;  but  on  close  examination 
some  of  the  graduations  will  be  found  to  exceed,  and  others  to  fall 
short  of,  the  true  inch. 

The  scales  assume,  of  course,  the  relative  degree  of  accuracy  of 
the  screw  employed.  No  test  is  more  severe ;  and  when  these  scales 
are  examined  by  means  of  two  microscopes  under  a  magnifying 
power  of  ten  or  twenty  times,  the  most  minute  errors  become 
abundantly  obvious  from  the  divisions  of  the  scales  failing  to  in- 
tersect the  cross  wires  of  the  instrument ;  the  result  clearly  indi- 
cates corresponding  irregularities  in  the  coarseness  of  the  screw  at 
the  respective  parts  of  its  length.  An  accustomed  eye  can  thus 
detect,  with  the  microscope,  differences  not  exceeding  the  one  thirty- 
thousandth  part  of  an  inch,  the  twenty-fi ve-thousandth  part  being 
comparatively  of  easy  observation. 

Figs.  509  and  512  show  a  large  chucking  and  reaming  lathe 
built  at  Lowell,  Massachusetts. 

Figs.  510  and  511  show  a  chucking  and  reaming  lathe  manu- 
factured at  Lowell.  This  instrument  is  geared  with  a  rest  for 
holding  drills  and  reamers  moved  by  a  toothed  rack,  backhead 


470  THE  PRACTICAL  METAL- WORKER'S  ASSISTANT. 

stock,  adjustable  sideways,  cast-iron  cone-pulleys,  gun  metal  bear- 
ings, and  cast-steel  spindle. 

Fig.  512. 


Fig.  513  is  an  engine  lathe  manufactured  at  the  Lowell  Machine 
Shop,  Lowell,  Massachusetts.  Its  swing  is  50  inches  over  the  sills, 
and  32  over  the  rest. 

Fig.  513. 


The  bed  of  this  lathe  is  cast  in  one  piece,  the  feed  motion  is 
carried  by  a  screw,  the  tool  rest  held  down  by  gibs  under  the  slides, 
and  moved  on  a  toothed  rack  and  pinion  by  hand. 

SCREW  THREADS  CONSIDERED  IN  BESPECT  TO  THEIR  PROPOR- 
TIONS, FORMS,  AND  GENERAL  CHARACTERS. — The  proportions  given 
to  screws  employed  for  attaching  together  the  different  parts  of 
works  are  in  nearly  every  case  arbitrary,  or,  in  other  words,  they 
are  determined  almost  by  experience  alone  rather  than  by  rule, 
and  with  little  or  no  aid  from  calculation,  as  will  be  shown. 

In  addition  to  the  ordinary  binding  screws,  which,  although  arbi- 
trary, assume  proportions  not  far  distant  from  a  general  average, 
many  screws,  either  much  coarser  or  finer  than  usual,  are  continu- 


SCREW-CUTTING  TOOLS.  471 

ally  required  for  specific  purposes ;  as  are  likewise  other  screws  of 
some  definite  number  of  turns  per  inch — as  2,  10,  12,  20,  etc. — in 
order  to  effect  some  adjustment  or  movement  having  an  immediate 
reference  to  ordinary  lineal  measure.  But  all  these  must  be  con- 
sidered as  still  more  distant  than  common  binding  screws  from  any 
fixed  proportions,  and  not  to  be  amenable  to  any  rules  beyond  those 
of  general  expediency. 

Neither  the  pitch,  diameter,  nor  depth  of  thread,  can  be  adopted 
as  the  basis  from  which  to  calculate  the  two  other  measures,  on 
account  of  the  different  modes  in  which  the  three  influence  the 
effectiveness  of  the  screw ;  nor  can  the  proportions  suitable  to  the 
ordinary  f  inch  binding  screw  be  doubled  for  the  1£  inch  screw,  or 
halved  for  that  of  f  inch,  as  every  diameter  requires  its  individual 
scale  to  be  determined  in  great  measure  by  experiment  in  order  to 
produce  something  like  a  mean  proportion  between  the  dissimilar 
conditions,  which  will  be  separately  explained  in  various  points  of 
view. 

The  reasons  for  the  uncertainty  of  measure  in  the  various  fixing 
screws  required  in  the  constructive  arts  are  sufficiently  manifest ; 
as  first,  the  force  or  strain  to  which  a  screw  is  exposed,  either  in  the 
act  of  fixing  or  in  the  office  it  has  afterward  to  perform,  can  rarely 
be  told  by  calculation ;  and  secondly,  a  knowledge  of  the  strain  the 
screw  itself  will  safely  endure  without  breaking  in  two,  or  without 
drawing  out  of  the  nut,  is  equally  difficult  of  attainment ;  nor 
thirdly,  can  the  deduction  for  friction  be  truly  made  from  that 
force  the  screw  should  otherwise  possess  from  its  angle  or  pitch 
when  viewed  as  a  mechanical  power,  or  as  a  continuous  circular 
wedge. 

The  force  required  in  the  fixing  of  screws  takes  a  very  wide 
range,  and  is  faintly  indicative  of  the  strain  exerted  on  each.  The 
watchmaker,  in  fixing  his  binding  screws,  employs  with  great 
delicacy  a  screw-driver  the  handle  of  which  is  smaller  than  an 
ordinary  drawing  pencil ;  while  for  screws,  say  of  five  inches  dia- 
meter, a  lever  of  six  or  seven  feet  long  must  be  employed  by  the 
engineer,  with  the  united  exertions  of  as  many  men.  But  in 
neither  case  do  we  arrive  at  any  available  conclusion,  as  to  the  pre- 
cise force  exerted  upon,  or  by  each  screw;  nor  of  the  greatest  strain 
that  each  will  safely  endure. 

The  absolute  measures  of  the  strength  of  any  individual  screw 
being  therefore  nearly  or  quite  unattainable,  all  that  can  be  done 
to  assist  the  judgment,  is  to  explain  the  relative  or  comparative  mea- 
sures of  strength  in  different  screws,  as  determined  by  the  three 
conditions  which  occur  in  every  screw;  whether  it  be  right  or  left- 
handed,  of  single  or  of  multiplex  thread,  or  of  any  section  what- 
ever ;  and  which  three  conditions  follow  different  laws,  and  con- 
jointly, yet  oppositely  determine  the  fitness  of  the  screw  for  its  par- 
ticular purpose,  and  therefore  tend  to  perplex  the  choice. 

The  three  relative  or  comparative  measures  of  strength  in  different 
screws  are :  first,  the  mechanical  power  of  the  thread,  which  is  de- 


472 


THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 


rived  from  its  pitch ;  secondly,  the  cohesive  strength  of  the  bolt,  which 
is  derived  from  its  transverse  section;  thirdly,  the  cohesive  strength 
of  the  hold,  which  is  derived  from  the  interplacement  of  the  threads 
of  the  screw  and  nut. 

These  conditions  will  be  first  considered,  principally  as  regards 
ordinary  binding  screws,  and  screw  bolts  and  nuts,  of  angular 
threads,  and  which  indeed  constitute  by  far  the  largest  number  of 
all  the  screws  employed ;  screws  of  angular  and  square  threads  will 
be  then  compared. 

The  comparative  sections,  Figs.  514  to  517,  represent  screws  of 
the  same  diameters,  and  in  all  of  which  the  depth  of  the  thread  is 
equal  to  the  width  of  the  groove;  Figs.  515  and  517  show  the  ordi- 
dinary  proportions  of  f  inch  angular  and  square  thread  screws ; 
514  and  516  are  respectively  as  fine  and  as  coarse  again  as  515. 


516 


517. 


Various  measures  of  the  screws  which  require  little  further  ex- 
planation are  subjoined  in  a  tabular  form;  and  the  relative  degrees 
of  strength  possessed  by  each  screw  under  three  different  points  of 
view,  are  added. 


MEASURES   AND    RELATIVE   STRENGTHS    OP   THE    SCREWS. 

Fig. 
514. 

Fig. 
515. 

Fig. 
516. 

Fig. 
517. 

External  diameters  in  hundredths  of  an  inch  .     .     .     • 
Internal  diameters  in  hundredths  of  an  inch    .... 

.75 

.65 

.75 
.55 

.75 

.35 

.75 
.55 

Number  of  threads  per  inch,  or  rates  of  the  screws  .     . 

JO 

10. 

5. 

5. 

Depths  and  widths  of  the  threads  in  hundredths      .     . 

.05 

.10 

.20 

.10 

Angles  of  the  threads  on  the  external  diameters*     .     . 
Angles  of  the  threads  on  the  internal  diameters*     .     . 

1°28' 

2°33' 
3°28' 

5°  5' 

lff°47' 

5°  5' 
6°55' 

Relative  mechanical  powers  of  the  threads      .... 
Relative  cohesive  strengths  of  the  bolts  

20 

4 

10 
3 

5 
1 

5 
3 

Relative  cohesive  strengths  of  hold  of  the  screws     .     . 

65 

55 

35 

27* 

Relative  cohesive  strengths  of  hold  of  the  nuts    .     .     . 

75 

75 

75 

37* 

Square  thread  screws,  have  about  twice  the  pitch  of  angular 
threads  of  similar  diameters,  and  Fig.  517  estimated  in  the  same 
manner  as  the  angular,  will  stand  by  comparison  as  follows.  The 

*  The  angles  of  the  threads  of  screws  are  calculated  trigonometrically,  the 
circumference  of  the  bolt  being  considered  as  the  base  of  aright-angled  triangle, 
and  the  pitch  as  the  height  of  the  same. 

The  author  has  adopted  the  following  mode,  which  will  be  found  to  require 
the  fewest  figures  ;  namely,  to  divide  the  pitch  by  the  circumference,  and  to 
seek  the  product  in  the  table  of  tangents  ;  decimal  numbers  are  to  be  used, 
and  it  is  sufficiently  near  to  consider  the  circumference  as  exactly  three  times 
the  diameter. 


SCREW-CUTTING  TOOLS.  473 

square  thread,  Fig.  517,  will  be  found  to  be  equal  in  power  to 
Fig.  516,  the  pitch  being  alike  in  each.  In  strength  of  bolt  to  be 
equal  to  Fig.  515,  their  transverse  areas  being  alike.  And  in 
strength  of  hold,  to  possess  the  half  of  that  of  Fig.  515,  because  the 
square  thread  will  from  necessity  break  through  the  bottom  of  the 
threads,  or  an  interrupted  line  exactly  like  the  dotted  line  in  Fig. 
516,  that  denotes  just  half  the  area  or  extent  of  base,  of  the  thread 
of -Fig.  515;  which  latter  covers  the  entire  surface  of  the  contained 
cylinder,  and  not  the  half  only. 

T/ie  mechanical  power  of  the  thread  is  derived  from  its  pitch.  The 
power,  or  the  force  of  compression,  is  directly  as  the  number  of 
threads  per  inch,  or  as  the  rate;  so  that  neglecting  the  friction  in 
both  cases,  Fig.  514  grasps  with  four  times  the  power  of  Fig.  516, 
because  its  wedge  or  angle  is  four  times  as  acute. 

When,  however,  the  angle  is  very  great,  as  in  the  screws  of  fly- 
presses,  which  sometimes  exceed  the  obliquity  of  45  degrees,  the 
screw  will  not  retain  its  grasp  at  all ;  neither  will  a  wedge  of  45 
degrees  stick  fast  in  a  cleft.  Such  coarse  screws  act  by  impact ; 
they  give  a  violent  blow  on  the  die  from  the  momentum  of  the^fo/ 
(namely,  the  loaded  lever,  or  the  wheel  fixed  on  the  press-screw) 
being  suddenly  arrested ;  they  do  not  wedge  fast,  but  on  the  con- 
trary, the  reaction  upwards  unwinds  and  raises  the  screw  for  the 
succeeding  stroke  of  the  fly-press. 

Binding  screws  which  are  disproportionately  coarse,  from  lean- 
ing towards  this  condition,  and  also  from  presenting  less  surface- 
friction,  are  liable  to  become  loosened  if  exposed  to  a  jarring  ac- 
tion. But  when,  on  the  contrary,  the  pitch  is  very  fine,  or  the 
wedge  is  very  acute,  the  surface  friction  against  the  thread  of  the 
screw  is  such,  as  occasionally  to  prevent  their  separation  when  the 
screw-bolt  has  remained  long  in  the  hole  or  nut,  from  the  adhesion 
caused  by  the  thickening  of  the  oil,  or  by  a  slight  formation  of 
rust. 

The  cohesive  strength  of  the  bolt  is  derived  from  its  transverse  section. 
The  screw  may  be  thus  compared  with  a  cylindrical  rod  of  the 
some  diameter  as  the  bottom  of  the  thread,  and  employed  in  sus- 
taining a  load ;  that  is,  neglecting  torsion,  which  if  in  excess  may 
twist  the  screw  in  two.  The  relative  strengths  are  represented  by 
the  squares  of  the  smaller  diameters :  in  the  screws  of  20,  10,  and 
5  angular  threads,  the  smaller  diameters  are  65,  55,  and  35 ;  the 
squares  of  these  numbers  are  4225,  3025,  and  1225,  which  may  be 
expressed  in  round  numbers  as  4,  3, 1 ;  and,  therefore,  the  coarsest 
screw,  Fig.  516,  has  transversely  only  one-fourth  the  area,  and  conse- 

For  the  external  angle  of  Fig.  516  say  .20+2.25=.0888,  and  this  quotient 
by  Button's  Tables  gives  5  deg.  5  min. 

For  the  internal  angle  of  Fig.  514  say  .05+1.95—0.2564,  and  by  Button's 
Tables,  1  deg.  28  min. 

In  this  method  the  pitch  is  considered  as  the  tangent  to  the  angle,  and  the 
division  effects  the  change  of  the  two  sides  of  the  given  right-angled  triangle, 
for  two  others,  the  larger  of  which  is  1  or  unity,  for  the  convenience  of  using 
the  tables. 


474  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

quently  one-fourth  the  strength  of  the  finest,  represented  in  the 
three  diagrams. 

The  cohesive  strength  of  the  hold  is  derived  from  the  helical  ridge  of 
the  external  screw,  being  situated  within  the  helical  groove  of  the  inter- 
nal screw.  The  two  helices  become  locked  together  with  a  degree 
of  firmness,  approaching  to  that  by  means  of  which  the  different 
particles  of  solid  bodies  are  united  in  a  mass ;  as  one  or  both  of 
the  ridges  must  be  in  a  great  measure  torn  off  in  the  removal  of 
the  screw,  unless  it  be  unwound  or  twisted  out. 

A  slight  difference  in  the  diameter  or  the  section  of  a  screw  and 
nut,  is  less  objectionable  than  any  variation  in  the  coarseness  or 
pitch ;  as  the  latter  difference,  even  when  very  minute,  will  pre- 
vent the  screw  from  entering  the  hole,  unless  the  screw  is  made 
considerably  smaller  than  it  ought  to  be,  and  even  then  it  will 
bear  very  imperfectly,  or  only  on  a  few  places  of  the  nut. 

To  attempt  to  alter  a  screwed  hole  by  the  use  of  a  tap  of  a  dif- 
ferent pitch,  is  equally  fatal,  as  will  be  seen  by  the  annexed  dia- 


Fig.  518. 


www/ 


gram,  Fig.  518.  For  instance,  the  upper  line  a,  contains  exactly  4 
threads  per  inch,  and  the  middle  line  or  b,  has  4£  threads ;  they 
only  agree  at  distant  intervals.  The  lowest  line  c,  shows  that  which 
would  result  from  forcing  a  tap  of  4  threads  such  as  a  into  a  hole 
which  had  been  previously  tapped  with  the  4£  thread  screw  b,  the 
threads  would  be  said  to  cross,  and  would  nearly  destroy  each 
other ;  the  same  result  would  of  course  occur  from  employing  4  or 
5  thread  dies  on  a  screw  of  4£  threads  per  inch. 

Therefore,  unless  the  screw  tackle  exactly  agree  in  pitch  with 
the  previous  thread,  it  is  needful  to  remove  every  vestige  of  the 
former  thread  from  the  screw  or  hole ;  otherwise  the  result  drawn 
at  c,  must  ensue  in  a  degree  proportionate  to  the  difference  of  the 
threads,  and  a  large  portion  of  the  bearing  surface,  and  conse- 
quently, of  the  strength  and  durability  of  the  contact,  would  each 
be  lost.  Some  idea  may  thence  be  formed  of  the  real  and  irreme- 
diable drawback  frequently  experienced  from  the  dissimilarity  of 
screwing  apparatus ;  nearly  to  agree  will  not  suffice,  as  the  pitch 
should  be  identical. 

The  nut  of  a  f -inch  screw  bolt  is  usually  f  inch  thick,  as  it  is 


SCREW-CUTTING  TOOLS.  475 

considered  that  when  the  threads  are  in  good  contact,  and  collec- 
tively equal  to  the  diameter  of  the  bolt,  that  the  mutual  hold  of 
the  threads  exceeds  the  strength  either  of  the  bolt  or  nut ;  and 
therefore  that  the  bolt  is  more  likely  to  break  in  two,  or  the  nut 
to  burst  open,  rather  than  allow  the  bolt  to  draw  out  of  the  hole, 
from-  the  thread  stripping  off. 

When  screws  fit  into  holes  tapped  directly  into  the  castings  or 
other  parts  of  mechanism,  it  is  usual  to  allow  still  more  threads  to 
be  in  contact,  even  to  the  extent  of  two  or  more  times  the  diame- 
ter of  the  screw,  so  as  to  leave  the  preponderance  of  strength 
greatly  in  favor  of  the  hold ;  that  the  screw,  which  is  the  part 
more  easily  renewed,  may  be  nearly  certain  to  break  in  two,  rather 
than  damage  the  castings  by  tearing  out  the  thread  from  the 
tapped  hole. 

Should  the  internal  and  external  screws  be  made  in  the  same 
material,  that  is  both  of  wood,  brass  or  iron,  the  nut  or  internal 
screw  is  somewhat  the  stronger  of  the  two.  For  example,  in  the 
screw  Fig.  515,  the  base  of  the  thread  is  a  continuous  angular 
ridge,  which  occupies  the  whole  of  the  cylindrical  surface  repre- 
sented by  the  dotted  line.  Therefore  the  force  required  to  strip 
off  the  thread  from  the  bolt,  is  nearly  that  required  to  punch  a 
cylindrical  hole  of  the  same  diameter  and  length  as  the  bottom  of 
the  thread ;  for  in  either  case  the  whole  of  the  cylindrical  surface 
has  to  be  stripped  or  thrust  off  laterally,  in  a  manner  resembling 
the  slow,  quiet  action  of  the  punching  or  shearing  engine. 

But  the  base  of  the  thread  in  the  nut,  is  equal  to  the  cylindrical 
surface  measured  at  the  top  of  the  bolt, 'and  consequently,  the  mate- 
rials being  the  same,  and  the  length  the  same,  considering  the 
strength  of  the  nut  for  Fig.  515  to  be  75,  the  strength  of  the  bolt 
would  be  only  55,  or  they  would  be  respectively  as  the  diame- 
ters of  the  top  and  bottom  of  the  thread ;  although  when  the  bolt 
protrudes  through  the  nut,  the  thread  of  the  bolt  derives  a  slight 
additional  strength,  from  the  threads  situated  beyond  the  nut,  and 
which  serve  as  an  abutment. 

It  is  however  probable  that  the  angular  thread  will  not  strip  off 
at  the  base  of  the  threads,  either  in  the  screw  or  nut,  but  will  break 
through  a  line  somewhere  between  the  top  and  bottom :  but  these 
results  will  occur  alike  in  all,  and  will  not  therefore  materially 
alter  the  relation  of  strength  above  assumed. 

Comparing  Figs.  514,  515,  and  516,  upon  the  supposition  that 
the  bolts  and  nuts  exactly  fit  or  correspond,  the  strengths  of  the 
three  nuts  are  alike,  or  as  75,  and  those  of  the  bolts  are  as  65,  55, 
and  35,  and  therefore  the  advantage  of  hold  lies  with  the  bolt 
of  finest  thread ;  as  the  finer  the  thread,  the  more  nearly  do  the 
bolt  and  nut  approach  to  equality  of  diameter  and  strength. 

Supposing,  however,  for  the  purpose  of  explanation,  that  instead 
of  the  screws  and  nuts  being  carefully  fitted,  the  screws  are  each 
one-tenth  of  an  inch  smaller  than  the  diameters  of  the  respective 
taps  employed  in  cutting  the  three  nuts ;  Fig.  514  would  draw 


476  THE  PRACTICAL   METAL-WOEKEB  S  ASSISTANT. 

entirely  out  without  holding  at  all ;  the  penetration  and  hold  of 
Fig.  515  would  be  reduced  to  half  its  proper  quantity ;  and  that 
of  Fig.  516  to  three-fourths;  and  the  last  two  screws  would  strip  at 
a  line  more  or  less  elevated  above  the  base  of  .the  thread,  and 
therefore  the  more  easily  than  if  the  diameters  exactly  agreed. 

The  supposed  error,  although  monstrous  and  excessive,  shows 
that  the  finer  the  thread,  the  greater  also  should  be  the  accuracy  of 
contact  of  such  screws ;  and  it  also  shows  the  impolicy  of  employ- 
ing fine  threads  in  those  situations  where  they  will  be  subjected  to 
frequent  screwing  and  unscrewing,  and  also  to  much  strain.  As 
although  when  they  fit  equally  well,  fine  threads  are  somewhat 
more  powerful  than  coarse,  in  hold  as  well  as  in  mechanical 
power ;  the  fine  are  also  more  subject  to  wear,  and  they  receive 
from  such  wear,  a  greater  and  more  rapid  depreciation  of  strength, 
than  threads  of  the  ordinary  degrees  of  coarseness. 

In  a  screw  of  the  same  diameter  and  pitch,  the  ultimate  strength 
is  diminished  in  a  twofold  manner  by  the  increase  of  the  depth  of 
the  thread ;  first  it  diminishes  the  traverse  area  of  the  bolt,  which 
is  therefore  more  disposed  to  break  in  two ;  and  secondly,  it 
diminishes  the  individual  strength  of  each  thread,  which  becomes 
a  more  lofty  triangle  erected  on  the  same  base,  and  is  therefore 
more  exposed  to  fracture  or  to  be  stripped  off. 

But  the  durability  of  machinery  is  in  nearly  every  case  increased 
by  the  enlargement  of  the  bearing  surfaces,  and  therefore  as  the 
thread  of  increased  depth  presents  more  surface-bearing,  the  deep 
screw  has  constantly  greater  durability  against  the  friction  or  wear, 
arising  from  the  act  of  screwing  and  unscrewing.  The  durability 
of  the  screw  becomes  in  truth  a  fourth  condition,  to  be  borne  in 
mind  collectively  with  those  before  named. 

It  frequently  happens  that  the  diameters  of  screwed  works  are 
so  considerable,  that  they  can  neither  break  nor  burst  after  the 
manner  of  bolts  and  nuts ;  and  if  such  large  works  yield  to  the 
pressures  applied,  the  threads  must  be  the  part  sacrificed.  If  the 
materials  are  crystalline,  the  thread  crumbles  away,  but  in  those 
which  are  malleable  and  ductile,  the  thread,  instead  of  stripping 
off  as  a  wire,  sometimes  bends  until  the  resisting  side  presents  a 
perpendicular  face,  then  overhangs,  and  ultimately  curls  over: 
this  disposition  is  also  shown  in  the  abrasive  wear  of  the  screw 
before  it  yields. 

^  Comparing  the  square  with  the  angular  thread  in  regard  to  fric- 
tion, the  square  has  less  friction,  because  the  angular  edges  of  the 
screw  and  nut,  mutually  thrust  themselves  into  the  opposite  angular 
grooves  in  the  manner  of  the  wedge.  The  square  thread  has  also 
the  advantage  of  presenting  a  more  direct  thrust  than  the  angular, 
because  in  each  case  the  resistance  is  at  right  angles  to  the  side  of 
the  thread,  and  therefore  in  the  square  thread  the  resistance  is  very 
nearly  in  the  line  of  its  axis,  whereas  in  the  angular  it  is  much 
more  oblique. 

From  these  reasons,  the  square  thread  is  commonly  selected  for 


SCREW-CUTTING  TOOLS. 


477 


presses,  and  for  regulating  screws,  especially  those  in  which 
rapidity  of  pitch,  combined  with  strength,  is  essential ;  but  as 
regards  the  ordinary  attachments  in  machinery,  the  grasp  of  the 
angular  thread  is  more  powerful,  from  its  pitch  being  generally 
about  as  fine  again,  and,  as  before  explained,  angular  screws  and 
nuts  are  somewhat  more  easily  fitted  together. 

The  force  exerted  in  bursting  open  a  nut,  depends  on  the  angle 
formed  by  the  sides  of  the  thread,  when  the  latter  is  considered  as 
part  of  a  cone,  or  as  a  wedge  employed  in  splitting  timber.  For 
instance,  in  the  square  thread  screw,  the  thread  forms  a  line  at 
right  angles  to  the  axis,  and  which  is  dotted  in  the  figure  519  ;  it 
is  not  therefore  a  cone,  but  simply  compresses  the  nut,  or  attempts 
to  force  the  metal  before  it.  In  the  deep  thread,  Fig.  520,  the 
wedge  is  obtuse,  and  exerts  much  less  bursting  effort  than  the 


Figs.  519 


521. 


acute  cone  represented  in  the  shallow  thread  screw,  Fig.  521 ; 
therefore,  the  shallower  the  angular  thread,  the  more  acute  the 
cone,  and  the  greater  the  strain  it  throws  upon  the  nut.  The 
transverse  measure  of  nuts,  whether  they  are  square  or  hexagonal, 
is  usually  about  twice  the  diameter  of  the  bolt,  as  represented  in 
the  figures,  and  this  in  general  suffices  to  withstand  the  bursting 
effort  of  the  bolt. 

In  the  table  of  dimensions  of  nuts,  in  "  Byrne's  Engineer's 
Pocket  Companion,"  the  traverse  measures  decrease  in  the  larger 
nuts ;  the  breadth  of  a  nut  for  a  J  inch  bolt  is  stated  as  1  inch, 
that  for  a  2  £  inch  bolt  as  four  inches. 

Those  nuts,  however,  which  are  not  used  for  grasping,  but  for 
the  regulating  screws  of  slides  and  general  machinery,  are  made 
much  thicker,  so  as  to  occupy  as  much  of  the  length  of  the  screw 
as  two,  three,  or  more  times  its  diameter.  This  greatly  increases 
their  surface-contact  and  durability. 

Should  it  be  required  to  be  able  to  compensate  the  nut,  or  to  re- 
adapt  it  to  the  lessened  size  of  the  screw  when  both  have  been 
worn,  the  nut  is  made  in  two  parts  and  compressed  by  screws,  or  it 
is  made  elastic  so  as  to  press  upon  ^e  screw.  The  nuts  for  angular 
threads  are  divided  diametrically  and  reunited  by  two  or  more 
screws,  as  in  Fig.  522 — in  fact,  like  the  semi-circular  bearings  of 
ordinary  shafts ;  as  then  by  filing  a  little  of  the  metal  away  from 


478 


THE   PKACTICAL   METAL-WORKER 'S  ASSISTANT. 


between  the  two  halves  of  the  nut,  they  may  be  closed  upon  the 
angular  ridges  of  the  thread. 

The  nuts  of  square  threads  by  a  similar  treatment  would,  on 
being  closed,  fit  accurately  upon  the  outer  or  cylindrical  surface  of 
the  square  thread  screw  ;  but  the  lateral  contact  would  not  be  re- 
stored ;  these  nuts  are,  therefore,  divided  transversely,  as  shown  in 
Fig.  523,  or  they  are  made  as  two  detached  nuts  placed  in  contact. 
When,  therefore,  a  small  quantity  is  removed  from  between  them 
with  the  file,  or  that  they  are  separated  by  one  or  more  thicknesses 
of  paper,  the  one-half  of  the  nut  bears  on  the  right  hand  side  of 
the  square  worm,  the  other  on  the  left. 


Figs.  522 


Either  of  these  methods  removes  the  "  end  play"  or  the  "  loss  of 
time,"  by  which  expression  is  meant  that  partial  revolution  to  and 
fro  which  may  be  given  to  a  worn  screw  without  producing  any 
movement  or  traverse  in  the  slide  upon  which  the  screw  acts.  It  is 
usual,  before  cutting  the  nuts  in  the  lathe  or  with  screw  traps,  to 
divide  the  nuts,  and  to  reunite  them  with  soft  solder,  or  it  is  better 
to  hold  them  together  with  the  permanent  screws  whilst  cutting  the 
thread. 

But  the  screws  of  slides  are  very  apt  to  become  most  worn  in 
the  middle  of  their  length,  or  at  the  one  end,  leaving  the  other 
parts  nearly  of  their  original  size.  It  is  then  best  to  replace  them 
by  new  screws,  as  the  former  method  of  adjusting  the  nuts  cannot 
be  used ;  although  recourse  may  occasionally  be  had  to  some  of 
the  various  methods  of  springing,  or  the  elastic  contrivances  com- 
monly employed  in  delicate  mathematical  and  astronomical  instru- 
ments. _  Although  these  should  be  perfectly  free  from  shake  or 
uncertainty  of  motion,  they  do  not  in  general  require  the  firm, 
massive,  unyielding  structure  of  engineering  works  and  machinery. 

Two  kinds  of  the  elastic  nuts  alone  are  shown ;  in  Fig.  524  the 
saw-cut  extends  throughout  the,  length  of  the  nut,  but  sometimes  a 
portion  in  the  middle  is  left  uncut ;  the  nut  is  usually  a  little  set-in, 
or  bent  jnwards  with  the  hammer,  so  as  to  press  upon  the  screw. 
In  Fig.  525  the  two  pieces  a  and  b  bear  against  opposite  sides  of  the 


SCREW-CUTTING  TOOLS.  479 

threads,  and  b  only  is  fixed  to  the  slide  as  in  Fig.  523 ;  the  correc- 
tion is  now  accomplished  by  interposing  loosely  around  the  screw 
and  between  the  halves  of  the  nut,  a  spiral  spring  sufficiently  strong 
to  overcome  the  friction  of  the  slide  upon  the  fittings ;  the  .same 
contrivance  is  variously  modified,  sometimes  two  or  four  spiral 
springs  are  placed  in  cavities  parallel  with  the  ^crew. 

The  slide  resists  firmly  any  pressure  from  a  to  b,  as  the  fixed  half 
of  the  nut  lies  firmly  against  the  side  of  the  thread  presented  in  that 
direction,  but  the  pressure  from  b  to  a  is  sustained  alone  by  the 
spiral  spring ;  when,  therefore,  the  pressure  exceeds  the  strength 
of  the  spring,  the  slide  nevertheless  moves  endways  to  the  extent 
of  the  misfit  in  the  piece  b,  and  which,  but  for  the  spring,  would 
/dlow  the  slide  to  shake  endways.  In  absolute  effect  the  contrivance 
is  equivalent  to  a  single  nut  such  as  b  alone,  which,  although  pos- 
sessing end  play  if  pulled  towards  &  by  a  string  and  weight,  would 
always  keep  in  contact  with  the  one  side  of  the  worm,  unless  the 
resistance  were  sufficient  to  raise  the  weight.  The  method  is  there- 
fore only  suited  to  works  requiring  delicacy  rather  than  strength, 
and  the  spring,  if  excessively  strong,  would  constantly  wear  the 
two  halves  of  the  nut  with  injudicious  friction  and  haste. 

The  several  threads  represented  in  Figs.  526  to  538  may  be  con- 
sidered to  be  departures  from  the  angular  thread  Fig.  526  and  the 
square  thread  Fig.  535,  which  are  by  far  the  most  common. 

The  choice  of  section  is  collectively  governed :  First,  by  the 
facility  of  construction,  in  which  the  plain  angular  thread  excels. 
Secondly,  by  the  best  resistance  to  strain,  which  is  obtained  in  the 
square  thread.  Thirdly,  by  the  near  equality  of  strength  in  the 
internal  and  external  screw.  For  similar  materials  the  space  and 
thread  should  be  symmetrical,  as  in  the  square  thread,  and  in  Figs. 
526  to  530,  which  screws  are  proper  for  metal  works  generally ; 
whereas  in  dissimilar  materials  the  harder  of  the  two  should  have 
the  slighter  thread,  as  in  the  iron  screws,  Figs.  531  to  534,  intended 
to  be  screwed  into  wood ;  the  substance  of  the  screw  is  supposed 
to  be  below  the  line,  and  the  head  to  the  right  hand.  Fourthly,  by 
the  resistance  to  accidental  violence,  either  to  the  screws,  or  to  the 
screwing  tools,  which  is  best  obtained  by  the  rejection  of  sharp 
angles  or  edges,  as  in  the  several  rounded  threads.  This  fourfold 
choice  of  section,  like  every  other  feature  of  the  screw,  is  also 
mainly  determined  by  experience  alone. 

Fig.  526,  in  which  the  angle  is  about  60  degrees,  is  used  for  most 
of  the  screws  made  in  wood,  whether  in  the  screw-box  or  the  turn- 
ing lathe ;  and  also  for  a  very  large  proportion  of  the  screw  bolts 
of  ordinary  mechanism.  Sometimes  the  points  of  the  screw  tool 
measure  nearly  90  degrees,  as  in  the  shallow  thread,  Fig.  527,  used 
for  the  thin  tubes  of  telescopes;  or  at  other  times  they  only 
measure  45  degrees,  as  in  the  very  deep  thread,  Fig.  528,  used  for 
some  mathematical  and  other  instruments.  The  angles  represented 
may  be  considered  as  nearly  the  extremes. 

In  originating  accurate  screws,  the  angular  thread  is  always 


480 


THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 


FigS. 


Sections  derived  from  the 

ANGULAR    THREAD. 


526  AVWVWVW 


AA/VWVWW 


529 


•AAAAAAAA/W 


530  A/VWWWW 

531  JUUUULAJUUVJU 

532  AAAAAAAAAA; 


selected,  because  tlie  figure 
of  the  thread  is  still  main- 
tained, whether  the  tool  cut 
on  one  or  on  both  sides  of 
the  thread,  in  the  course  of 
the  correctional  process. 

Fig.  529  is  the  angular 
thread  in  which  the  ridges 
are  more  or  less  truncated  to 
increase  the  strength  of  the 
bolt ;  it  may  be  viewed  as  a 
compound  of  the  square  and 
angular  thread.  % 

Fig.  530  is  the  angular 
thread  in  which  the  tops  and 
bottoms  are  rounded ;  it  is 
much  used  in  engineering 
works,  and  is  frequently 
called  a  round  thread. 

In  Fig.  531  the  thread  is 
more  acute,  and  truncated 
only  at  the  bottom  of  the 
screw.  This  is  used  for 
joinery- work,  and  greatly  in- 
creases the  hold  upon  the 
wood.  Fig.  532  is  obviously 
derived  from  Fig.  531,  and  is 
used  for  the  same  purpose. 

In  Fig.  533,  which  is  also 
a  screw  for  wood,  the  face 
that  sustains  the  hold  is  rec- 
tangular, as  in  the  square 
thread — the  other  is  beveled. 
Fig.  534  is  the  form  of  the 
patent  wood  screw  sometimes 
called  the  German  screw.  It 
is  hollowed,  to  throw  the  advantage  of  bulk  in  favor  of  the  softer 
material,  or  the  wood,  the  head  of  which  is  supposed  to  be  on 
the  right  hand.  In  the  last  four  figures,  the  substance  of  the 
screw  is  imagined  to  be  situated  below  the  line,  and  that  of  the 
wood  above. 

The  screws  which  are  inserted  into  wood  are  generally  made 
taper,  and  not  cylindrical,  in  order  that  they  may  cut  their  own 
nut  or  internal  thread.  Some  of  them  are  pointed,  so  as  to  pene- 
trate without  any  previous  hole  being  made — they  merely  thrust 
the  fibres  of  wood  on  one  side.  Screws  hold  the  most  strongly 
in  wood  when  inserted  horizontally  as  compared  with  the  po- 
sition in  which  the  tree  grew,  and  least  strongly  in  the  vertical 
position. 


533 


531 


535 


536 


537 


538 


Sections  derived  from  the 

SQUARE  THREAD. 


WXAjTlT 


*  SCREW-CUTTING  TOOLS.  481 

Fig.  535  represents  the  ordinary  square  thread  screw.  The 
space  and  thread  are  mostly  of  equal  width,  and  the  depth  is  either 
equal  to  the  width,  or  a  trifle  more,  say  one-sixth. 

Fig.  536  is  a  departure  from  Fig.  535,  and  has  been  made  for 
presses ;  and  Fig.  537  has  obviously  grown  out  of  the  last  from  the 
obliteration  of  the  angles.  Various  proportions  intermediate  be- 
tween Figs  537  and  530  are  used  for  round  threads. 

Tn  some  cases  where  the  screw  is  required  to  be  rapid,  one 
single  shallow  groove  is  made  of  angular,  square,  or  circular  sec- 
tion, leaving  much  of  the  original  cylinder  standing,  as  in  Fig.  538. 
For  very  slight  purposes  a  pin  only  is  fitted  to  the  groove  to  serve  as 
the  nut.  Should  the  resistance  be  greater,  many  pins,  or  a  comb 
may  be  employed,  and  this  was  the  earliest  form  of  nut ;  otherwise 
a  screwed  nut  may  be  used  with  a  single  thread.  But  when  the 
greatest  resistance  is  required  the  surface  bearing  of  the  nut  is  ex- 
tended by  making  the  thread  double,  triple,  etc.,  by  cutting  one  or 
more  intermediate  grooves  and  a  counterpart  nut. 

The  nuts  or  boxes  of  very  coarse  screws  for  presses  are  now 
mostly  cut  in  the  lathe,  although,  when  the  screwing  tools  were 
less  perfectly  understood,  the  nuts  were  frequently  cast.  Some- 
times lead,  or  alloys  of  similar  fusibility,  were  poured  in  betwixt 
the  screw  and  the  framework  of  the  machinery ;  but  for  nuts  of 
brass  and  gun-metal,  sand  moulds  were  formed.  The  screw  was- 
always  warmed  to  avoid  chilling  the  metal ;  and  for  brass,  it  was 
sometimes  heated  to  redness  and  allowed  to  cool,  so  as  slightly  to. 
oxidize  the  surface  and  lessen  the  disposition  to  a  union  or  natural 
soldering  of  the  screw  and  nut.  It  was  commonly  necessary  to- 
stretch  the  brass  by  an  external  hammering,  to  counteract  the 
shrinkage  of  the  metal  in  the  act  of  cooling,  and  to  assist  in  releas- 
ing from  the  screw  the  nut  cast  upon  it  in  this  manner.  The  mode 
is  by  no  means  desirable,  as  the  screw  is  exposed  to  being  bent 
from  the  rough  treatment,  and  to  being  ground  by  particles  of 
sand  adhering  to  the  brass. 

The  tangent  screws  used  for  screw  wheels  have  mostly  angular 
or  truncated  angular  threads,  Fig.  529,  as  screws  absolutely  square 
cannot  be  fitted  with  good  contact  and  freedom  from  shake  be- 
tween  the  thread  and  teeth  ;  and  probably  the  same  rules  by 
which  the  teeth  of  ordinary  wheels  and  racks  are  reciprocally  set 
out,  should  be  also  applied  to  the  delineation  of  the  teeth  of  worm 
wheels,  and  the  threads  or  teeth  of  their  appropriate  screws. 

Tangent  screws  are  occasionally  double,  triple,  or  quadruple,  in 
order  that  2,  3,  or  4  teeth  of  the  wheel  may  be  moved  during  each 
revolution  of  the  screw.  In  the  Piedmont  silk-mills,  this  principle 
is  carried  to  the  extreme,  as  the  screw  and  wheel  become  alike, 
and  revolve  turn  for  turn ;  the  teeth,  supposing  them  to  be  20,  are 
then  identical  with  those  of  a  20  thread  screw,  the  angular  coils  of 
which  cross  the  axis  at  the  angle  of  45°,  that  is,  when-  the  shafts 
lie  at  right  angles  to  each  other  ;  other  proportions  and  angles  may 
be  adopted.  In  realitv  they  fulfil  the  office  of  bevel  wheels,  or 


482  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

rather  of  skew-bevel  wheels,  in  which  latter  also,  the  axes,  from 
being  in  different  planes,  may  cross  each  other  ;  so  that  the  skew- 
bevel  wheels  may  be  in  the  centre  of  long  shafts,  but  which  cannot 
be  the  case  in  ordinary  bevel  wheels,  the  teeth  of  which  lie  in  the 
same  plane  as  the  axis  of  the  wheel.  The  Piedmont  wheels  act 
with  a  very  reduced  extent  of  bearing  or  contact  surface,  and  a 
considerable  amount  of  the  sliding  action  of  screws,  which  is  dis- 
advantageous in  the  teeth  of  wheels,  although  inseparable  from  all 
those  with  inclined  teeth,  and  which  are  indeed  more  or  less  dis- 
tant modifications  of  the  screw. 

When  the  obliquity  of  the  teeth  of  worm  wheels  is  small,  it 
gives  a  very  smooth  action,  but  at  the  expense  of  friction  ;  but  in 
ordinary  toothed  wheels,  the  teeth  are  exactly  square  across  or  in 
the  plane  of  the  axis,  and  the  aim  is  to  employ  rolling  contact, 
with  the  greatest  possible  exclusion  of  sliding,  from  amongst  the 
teeth. 

Having  treated  somewhat  in  detail  the  different  forms  of  screws, 
and  the  circumstances  which  adapt  them  to  their  several  purposes, 
I  have  now  to  consider  some  of  the  inconveniences  which  have 
unavoidably  arisen  from  the  indefinite  choice  of  proportions  in 
ordinary  screws,  and  also  some  of  the  means  that  have  been  pro- 
posed for  their  correction.  The  slight  discussion  of  the  more  im- 
portant of  these  topics  will  permit  the  introduction  of  various 
additional  points  of  information  on  this  almost  inexhaustible  sub- 
ject, the  screw. 

No  inconvenience  is  felt  from  the  dissimilarities  of  screws,  so 
long  as  the  same  screwing  tools  are  always  employed  in  effecting 
repairs  in,  or  additions  to,  the  same  works.  But  when  it  is  con- 
sidered, how  small  a  difference  in  either  of  the  measures  will  mar 
the  correspondence,  of  the  screw  and  nut ;  and  further,  the  very 
arbitrary  and  accidental  manner,  in  which  the  proportions  of  screw- 
ing apparatus  have  been  determined  by  a  variety  of  individuals, 
to  suit  their  particular  wants,  and  without  any  attempt  at  uniform- 
ity of  practice  (sometimes,  on  the  contrary,  with  an  express  de- 
sire to  be  peculiar),  it  is  perhaps  some  matter  of  surprise  when  the 
screws  made  in  different  establishments  properly  agree.  Indeed 
their  agreement  can  be  hardly  expected,  unless  they  are  derived 
from  the  same  source,  and  that  some  considerable  pains  are  taken 
not  to  depart  from  the  respective  proportions  first  adopted. 

In  a  few  isolated  cases  this  inconvenience  has  been  partially 
remedied  by  common  consent  and  adoption,  as  in  the  so-called  air- 
pump  thread,  which  is  pretty  generally  used  by  the  makers  of 
pneumatic  apparatus ;  and  to  a  certain  degree  also  in  some  of  the 
screws  used  in  gas-fittings  and  in  gun-work.  But  the  non-exis- 
tence of  any  common  standard  or  scale,  enhances  both  the  delay 
and  expense  of  repairs  in  general  mechanism,  and  leads  to  the 
occasional  necessity  for  making  additional  sizes  of  tools  to  match 
particular  works,  however  extensive  the  supply  of  screw  apparatus. 

The  perplexity  is  felt  in  a  degree  especially  severe  and  costly,  as 


SCREW-CUTTING  TOOLS.  483 

regards  marine  and  locomotive  engines,  which  from  necessity, -have 
to  be  repaired  in  localities  far  distant  from  those  in  which  they 
were  made ;  and  therefore  require  that  the  packet  station,  or  rail- 
way depot,  should  contain  sets  of  screwing  tackle,  corresponding 
with  those  used  by  every  different  manufacturer  whose  works 
have  to  be  dealt  with ;  otherwise,  both  the  delay  and  expense  are 
from  necessity  aggravated. 

Some  engineers  suggested  that  for  steam  machinery*  and  for  the 
purpose  of  engineering  in  general,  "  an  uniform  system  of  screw 
threads"  should  be  adopted.  The  following  table  may  be  consid- 
ered as  a  mean  between  the  different  kinds  of  threads  used  by  the 
leading  engineers  : 

Table  for  Angular  Thread  Screws. 


Diameters  in  inches     ... 
Nos.  of  threads  to  the  inch  . 


i|TSff|fi|Tff|i|« 
20|18|16|14  12  11 


Diameters  in  inches     ....       2J  2£  :2J 
Nos.  of  threads  to  the  inch  .     .       4  J4    ;3i  3J 


i 
10  9 


4i4 


HIH 

6  |6 

5"  5}  6J 
"-J2S2S 


ii 

6" 
2i2i 


In  selecting  this  scale,  the  following  very  judicious  course  was 
adopted  :  An  extensive  collection  was  made  of  screw-bolts  from 
the  principal  workshops,  and  the  average  thread  was  carefully  ob- 
served for  different  diameters.  The  J  inch,  J  inch,  1  and  1J  inch, 
were  particularly  selected,  and  taken  as  the  fixed  points  of  a  scale 
by  which  the  intermediate  sizes  were  regulated,  avoiding  small 
fractional  parts  in  the  number  of  threads  to  the  inch.  The  scale 
was  afterwards  extended  to  6  inches.  The  pitches  thus  obtained 
for  angular  threads  were  as  above : 

Above  the  diameter  of  1  inch  the  same  pitch  is  used  for  two 
sizes,  to  avoid  small  fractional  parts.  The  proportion  between  the 
pitch  and  the  diameter  varies  throughout  the  entire  scale. 

Thus  the  pitch  of  the  £  inch  screw  is  Jth  of  the  diameter ;  that 
of  the  £  inch  £th,  of  the  1  inch  |th,  of  the  4  inches  -^th,  and  of 
the  6  inches  fgth. 

The  depth  of  the  thread  in  the  various  specimens  is  then 
alluded  to.  In  this  respect  the  variation  was  greater  than  in  the 
pitch.  The  angle  made  by  the  sides  of  the  thread  being  taken  as 
an  expression  for  the  depth,  the  mean  of  the  angle  in  1  inch 
screws  was  found  to  be  about  55°,  which  was  also  nearly  the  mean 
i.i  screws  of  different  diameters.  Hence  it  was  adopted  throughout 
the  scale,  and  a  constant  proportion  was  thus  established  between 
the  depth  and  the  pitch  of  the  thread.  In  calculating  the  former, 
a  deduction  must  be  made  for  the  quantity  rounded  off,  amount- 
ing to  Jd  of  the  whole  depth,  i.  e.  ^th  from  the  top,  and  £th  from 
the  bottom  of  the  thread.  Making  this  deduction,  the  angle  of 
55°  gives  for  the  actual  depth  rather  more  than  fths,  and  less  than 
fds  of  the  pitch. 

As  regards  the  smaller  mechanism,  made  principally1  in  braw» 
and  steel,  such  as  mathematical  instruments  and  many  others,  the 


484 


THE   PKACTICAL   METAL-WORKER'S  ASSISTANT. 


screws  in  the  above  scale  below  half  an  inch  diameter  are  admitted 
to  be  too  coarse ;  and  the  acute  angular  threads  which  are  not 
rounded  are  decidedly  to  be  preferred,  from  their  greater  delicacy 
and  durability, — that  is,  when  their  strengths  are  proportioned  to 
the  resistances  to  which  they  are  exposed.  In  these  respects  the 
following  table  may  be  considered  preferable : 

Table  for  Small  Screws  of  Fine  Angular  Threads. 


Diameters  in  vulgar  fractions  of  the  inch  .  . 

I 

Af 

A 

ii 

ilit 

/5 

* 

i 

A 

i 

Diameters  in  hundredtbs  of  the  inch  nearly 

.60 

.47 

.44.41 

.37 

.34 

.31 

.88 

.25 

.22 

.20 

in 

on 

0, 

Diameters  in  hundredths  of  the  inch    .... 

.18 

.16 

.14  .12 

.10 

.: 

.08 

.07 

.06 

.05 

-04 

N        \\  r«  nf  thread1*  to  the  inf»h 

36 

40 

40 

48 

48 

56 

56 

64 

It 

SO 

100 

The  tables  above  given,  and  which  have  been  selected  and  not 
calculated,  will  serve  to  explain  the  inapplicability  of  the  mode  of 
calculation  proposed  in  various  popular  works, — namely,  for  an- 
gular thread  screws,  to  divide  the  diameter  by  8  for  the  pitch, 
when,  it  is  said,  such  screws  will  all  possess  the  angle  of  3|  degrees 
nearly ;  and  for  square  threads  to  divide  by  4,  thus  giving  an  angle 
of  7  degrees  nearly ;  therefore 

Angular  thread  screws  of86421£i    inches  diameter 
would  have  pitches  of  1     f     £    i     i   iV  *V   inches'  rise 

or  rates  of  1     1$  2     4    8   16  32   threads  per  inch, 

which  differ  greatly  from  2£  3    4£  8   12  20   Whitworth's   observa- 

tional numbers. 

By  the  use  of  the  constant  divisor  8,  the  one-inch  screw  agrees 
with  Whitworth's  table,  the  extremes  are  respectively  too  coarse 
and  too  fine ;  as  instead  of  8  being  employed,  the  actual  divisors 
vary  from  about  5  to  16,  and  therefore  a  theoretical  mode  would 
probably  require  a  logarithmic  scheme.  But  were  this  followed 
out  with  care,  the  adjustment  of  the  fractional  threads  so  obtained, 
for  those  of  whole  numbers,  would  completely  invalidate  the  pre- 
cision of  the  rule ;  and  the  result  would  not  be  in  any  respect 
better  than  when  adjusted  experimentally,  as  at  present. 

There  is  little  doubt  that  if  we  could  entirely  recommence  the 
labors  of  the  mechanist,  or  if  we  could  sweep  away  all  the  screw- 
ing tools  now  in  use,  and  also  all  the  existing  engines,  machines, 
tools,  instruments,  and  other  works,  which  have  been  in  part  made 
through  their  agency,  these  proposed  scales,  or  others  not  greatly 
differing  from  them  (as  the  choice  is  in  great  measure  arbitrary), 
would  be  found  of  great  general  advantage;  the  former  for  the 
larger,  the  latter  for  the  smaller  works.  But  until  all  these  myriads 
of  objects  are  laid  on  one  side,  or  that  repairs  are  no  longer  wanted 
in  them,  the  old  tools  must  from  absolute  necessity  be  retained,  in 
addition  to  those  proposed  in  these  or  any  other  schemes.  It 


SCREW-CUTTING   TOOLS.  485 

would  be  of  course  highly  judicious  in  new  manufacturing  estab- 
lishments to  adopt  such  conventional  scales,  as  they  would,  to  that 
extent,  promote  this  desirable  but  almost  impracticable  end,  namely, 
that  of  unity  of  system ;  but  which,  although  highly  fascinating 
and  apparently  tenable,  is  surrounded  by  so  many  interferences 
that  it  may  perhaps  be  considered  both  as  needless  and  hopeless  to 
attempt  to  carry  it  out  to  the  full,  or  to  make  the  system  absolutely 
universal ;  and  some  of  the  circumstances  which  affect  the  propo- 
sition will  be  now  briefly  given. 

First,  agreement  with  STANDARD  MEASURE,  although  convenient,  is 
not  indispensable.  It  may  be  truly  observed,  that  as  regards  the 
general  usefulness  of  a  screw  such  as  Fig.  516,  which  was  sup- 
posed to  measure  f  inch  diameter,  and  to  have  10  threads  per  inch, 
it  is  nearly  immaterial  whether  the  diameter  be  three  or  four  hun- 
dredths  of  an  inch  larger  or  smaller  than  f  of  an  inch ;  or  whether 
it  have  9,  Oy'gth,  9f,  10 1,  or  11  threads  per  inch,  or  any  fractional 
number  between  these  ;  or  whether  the  thread  be  a  trifle  more  or 
less  acute,  or  that  it  be  slightly  truncated <or  rounded  ;  so  long  as 
the  threads  in  the  screw  and  nut  are  but  truly  helical  and  alike,  in 
order  that  the  threads  mutually  bear  upon  each  other  at  every  part ; 
that  is,  as  regards  the  simple  purpose  of  the  binding  screw  or  bolt, 
namely,  the  holding  of  separate  parts  in  firm  contact.  And  as 
the  same  may  be  said  of  every  screw,  namely,  that  a  small  varia- 
tion in  diameter  or  pitch  is  commonly  immaterial,  it  follows 
that  the  good  office  of  a  screw  does  not  depend  on  its  having 
any  assigned  relation  to  the  standard  measure  of  this  or  any  other 
country. 

Secondly,  The  change  of  system  ivould  cause  an  inconvenient  in- 
crease in  the  number  of  screwing  tools  used.  Great  numbers  of  excel- 
lent and  useful  screws,  of  accidental  measures,  have  been  made  by 
various  mechanicians ;  and  the  author  hopes  to  be  excused  for 
citing  the  example  with  which  he  is  most  familiar. 

Between  the  years  1794  and  1800  I.  I.  Holtzapffel  made  a 
few  varieties  of  taps,  dies,  hobs,  and  screw  tools,  after  the  modes 
explained  at  pages  457  and  458.  These  varieties  of  pitch  were 
ultimately  extended  to  twelve  kinds,  of  each  of  which  was  formed 
a  deep  and  shallow  hob  or  screw  tool-cutter.  These,  when  meas- 
ured many  years  afterwards,  were  found  nearly  to  possess  in  each 
inch  of  their  length  the  threads  and  decimal  parts  that  are  ex- 
pressed in  the  following  table : 

Approximate  Values  of  1. 1.  HoltzapffeVs  Original  Screw  Threads. 


1 

6.58 

2 
8.25 

3 

9.45 

4 
13.09 

5 
16.5 

6 

19.89 

7 
22.12 

8 
25.71 

9 

28.88 

10 

36.10 

11 

39.83 

12 
55.11 

Threads  in  1  inch  . 

The  angle  of  the  deep  threads  is  about  50  degrees :  of  the  shallow  60  degrees. 


486  THE   PRACTICAL    METAL-WORKER'S  'ASSISTANT. 

This  irregularity  of  pitch  would  not  have  occurred  had  the  screw- 
lathe  with  change- wheels  been  then  in  use ;  but  such  .was  not  the 
case.  For  a  long  series  of  years  I.  I.  Holtzapffel  (in  conjunction 
with  his  partner,  I.  G.  Deyerlein,  from  1804  to  1827)  made,  as  oc- 
casion required,  a  large  or  small  screw,  a  coarse  or  fine,  a  shallow 
or  deep  thread,  and  so  forth.  By  which  accumulative  mode,  their 
series  of  working  taps  and  dies,  together  with  screw  tools,  gauges, 
chucks,  carriers,  and  a  variety  of  subordinate  apparatus,  became 
extended  to  not  less  than  one  hundred  varieties  of  all  kinds. 

About  one-third  of  these  sizes  have  been  constantly  used,  up  to 
the  present  time,  both  by  H.  &  Co.,  and  by  other  persons  to  whom 
copies  of  these  screw  tackles  have  been  supplied,  and  consequently 
many  thousands  of  screws  of  these  kinds  have  been  made :  this  im- 
plies the  continual  necessity  for  repairs  and  alterations  in  old 
works,  which  can  only  be  accomplished  by  retaining  the  original 
sizes. 

Since  the  period  at  which  H.  &  Co.  made  their  screw  lathe,  they 
have  employed  the  aliquot  threads  for  all  screws  above  half  an  inch ; 
indeed,  most  of  these  have  also  been  cut  in  the  screw  lathe.  To 
have  introduced  the  same  method  in  small  binding  screws  which 
are  not  made  in  the  screw  lathe,  but  with  the  diestocks  and  chasing 
tools,  would  have  doubled  the  number  of  their  working-screw  tackle, 
and  the  attendant  apparatus  ;  with  the  risk  of  confusion  from  the 
increased  number,  but  without  commensurate  advantage  as  regards 
the  purposes  to  which  they  are  applied. 

Doubtless  the  same  reasons  have  operated  in  numerous  other 
factories,  as  the  long  existence  of  good  useful  tools  has  often  less- 
ened, if  not  annulled,  the  advantage  to  be  derived  from  a  change 
which  refers  more  immediately  to  engineering  works ;  and  in  which 
a  partial  remedy  is  supplied,  as  steam-engines,  etc.,  are  frequently 
accompanied  with  spare  bolts  and  nuts,  and  also  with  corresponding 
screw  apparatus,  to  be  employed  in  repairs;  the  additional  cost  of 
such  parts  being  insignificant,  compared  with  the  value  of  the 
machinery  itself. 

Thirdly :  Unless  the  standard  sizes  of  screws  become  inconveni- 
ently numerous,  many  useful  kinds  must  be  omitted,  or  treated  as 
exceptions.  For  instance,  in  ordinary  binding  screws,  more  particu- 
larly in  the  smaller  sizes,  two  if  not  three  degrees  of  coarseness 
should  exist  for  every  diameter,  and  which  might  be  denominated 
the  coarse,  medium,  and  fine  series ;  and  again,  particular  circum- 
stances require  that  threads  should  be  of  shallow  or  of  deep  angular 
sections,  or  that  the  threads  should  be  rounded,  square,  or  of  some 
other  kinds ;  in  this  way  alone,  a  fitness  for  all  conditions  would 
inconveniently  augment  the  number  of  the  standards. 

In  many  cases  besides,  screws  of  several  diameters  are  made  of 
the  one  pitch.  In  order,  for  example,  that  the  hole  when  worn  may 
be  tapped  afresh,  and  fitted  with  screws  of  the  same  pitch  or  thread 
but  a  trifle  larger ;  or  that  a  partially  worn  screw  may  be  corrected 
with  the  dies  or  in  the  lathe,  and  fitted  with  a  smaller  nut  of  the 


SCREW-CUTTING   TOOLS.  487 

same  pitch.  A  succession  of  taps  of  the  same  pitch  also  readily 
permits  a  larger  screw  to  be  employed,  when  that  of  smaller  di- 
ameter has  been  found  to  break,  either  from  an  error  of  judgment 
in  the  first  construction  of  the  machine,  or  from  its  being  accident- 
ally submitted  to  a  strain  greater  than  it  was  intended  ever  to  bear. 

It  is  also  in  some  cases  requisite  to  have  right  and  left-hand 
screws  of  the  same  pitch,  that,  amongst  other  purposes,  they  may 
effect  simultaneous  yet  opposite  adjustments  in  machinery,  as  in 
some  universal  chucks :  and  also  some  few  screws,  the  threads  of 
which  are  double,  triple,  quadruple,  and  so  forth,  for  giving  to 
screws  of  small  diameters  considerable  rapidity  of  pitch  or  traverse, 
or  a  fixed  ratio  to  other  screws  associated  with  them,  in  the  same 
piece  of  mechanism. 

Under  ordinary  and  proper  management,  the  production  of  a 
number  of  similar  pieces  may  be  obtained  with  sufficient  exactitude, 
by  giving  to  the  tool  some  constant  condition.  For  example,  a  hun- 
dred nuts  tapped  with  the  same  tap,  will  be  very  nearly  alike  in 
their  thread;  and  a  hundred  screws  passed  through  the  hole  of  a 
screw-plate,  will  similarly  agree  in  size,  because  of  the  nearly 
constant  dimensions  of  the  tools,  for  a  moderate  period. 

In  practice,  the  same  relative  constancy  is  given  to  the  dies  of 
die-stocks  and  bolt  screwing  engines,  and  partly  so  to  the  tools  of 
the  screw-cutting  lathe.  Sometimes  the  pressure  or  adjusting  screw 
has  graduations  or  a  micrometer ;  and  numerous  contrivances  of 
eccentrics,  cams,  and  stops,  are  employed  to  effect  the  purpose  of 
bringing  the  die  or  turning-tool  to  one  constant  position,  for  each 
succeeding  screw ;  these  matters  are  too  varied  and  general  to  re- 
quire more  minute  notice.  Part  of  such  modes  may  serve  sufficiently 
well  for  ten,  or  even  a  hundred  screws,  provided  that  no  accident 
occur  to  the  tool ;  but  if  it  were  attempted  to  extend  this  mode  to 
a  thousand,  or  a  hundred  thousand  pieces,  the  same  tool  could  not, 
even  without  accident,  endure  the  trial ;  it  would  have  become  not 
only  unfit  for  cutting,  but  also  so  far  worn  away  as  to  leave  the 
last  of  the  works  materially  larger  than  the  first. 

In  respect  to  screws,  the  instrument,  the  size  of  which  claims  the 
most  importance,  is  perhaps  the  plug-tap,  or  that  which  removes 
the  last  portion  of  the  material,  and  therefore  determines  the  diam- 
eter of  the  internal  thread  ;  but  as  the  tap  is  continually,  although 
slowly,  wearing  smaller,  the  first  and  the  last  nut  made  with  it  un- 
avoidably differ  a  little  in  size.  It  is  on  account  of  the  wearing  of 
the  tap,  amongst  other  circumstances,  that  when  screws  and  nuts 
are  made  in  large  numbers,  and  are  required  to  be  capable  of  being 
interchanged,  it  becomes  needful  to  make  a  small  allowance  for 
error,  or  to  make  the  screws  a  trifle  smaller  than  the  nuts. 
'  In  order  to  retain  the  size  of  the  taps  used  by  Holtzapff'el  &  Co. 
they  some  years  ago  made  a  set  of  original  taps  exactly  of  the  size 
of  the  proposed  screws,  and  to  be  called  A ;  these,  when  two  or 
three  times  used  to  rub  off'  the  burrs,  were  employed  for  cutting 
regulating  dies  B,  of  the  form  of  Fig.  539,  with  two  shoulders,  so 


488  THE    PRACTICAL   METAL-WORKERS   ASSISTANT. 

that  the  dies  could  be  absolutely  closed,  and  yet  leave  a  space  for 
the  shaving  or  cuttings.  In  making  all  their  plug- taps,  they  are 
first  prepared  with  the  ordinary  shop  tools,  until 
the  taps  are  so  nearly  completed,  that,  grasped 
between  the  regulating  dies  B,  the  latter  close 
within  the  fortieth  or  fiftieth  of  an  inch,  therefore 
leaving  the  dies  B  next  to  nothing  to  perform  in 
the  way  of  cutting,  but  only  the  office  of  regulat- 
ing the  diameter  of  the  working  plug-taps.  Should 
the  dies  B  meet  with  any  accident,  the  taps  A, 
which  have  to  this  stage  been  only  used  for  one 
pair  of  regulating  dies,  exist  for  making  repeti- 
tions of  B.  This  method  has  been  found  to  fulfil 
its  intended  purpose  very  effectually  for  several 
years,  but  at  the  same  time  it  is  not  proposed  to 
apply  this  or  any  other  system  universally. 

In  conclusion,  it  may  be  said  that  by  far  the  most  important 
argument  in  favor  of  the  adoption  of  screws  of  aliquot  pitches  ap- 
plies to  steam-machinery  and  similar  large  works,  and  that,  princi- 
pally, because  it  brings  all  such  screws  within  the  province  of  the 
screw-lathe  with  change- wheels,  which  has  become,  in  engineering 
establishments  and  some  others,  a  very  general  tool.  This  valua- 
ble tool  alone  renders  each  engineer  in  a  great  measure  indepen- 
dent of  his  neighbor,  as  screws  of  2,  2£,  2  J,  3,  10,  or  20  threads  in 
the  inch,  are  readily  measured  with  the  common  rule,  and  copied 
with  the  screw-wheels,  and  a  single-pointed  tool,  or  an  ordinary 
comb  or  chasing  tool  with  many  points. 

And  therefore,  with  the  modern  facility  of  work,  were  engineers 
severally  to  make  their  screw  tackle  from  only  the  written  measures 
of  any  conventional  table,  they  would  be  at  once  abundantly  within 
reach  of  the  adjustment  of  the  tools,  and  that  without  any  standard 
guages;  the  strict  introduction  of  which'  would  almost  demand 
that  all  the  tools  made  in  uniformity  with  them  should  emanate 
from  one  centre,  or  be  submitted  to  some  office  for  inspection  and 
sanction — and  this  would  be  indeed  to  buy  the  occasional  advantage 
at  too  dear  a  rate. 

It  must,  however,  be  unhesitatingly  granted,  that  the  argument 
applies  but  little,  if  at  all,  to  a  variety  of  screws  which  from  their 
smaller  size  are  not  made  in  the  screw  lathe,  but  with  die-stocks 
and  the  hand-chasing  tools  only ;  and  which  are  employed  in 
branches  of  art  that  may  be  considered  as  almost  isolated  from  one 
another,  and  therefore  not  to  require  uniformity. 

For  instance,  the  makers  of  astronomical,  mathematical,  and 
philosophical  instruments,  of  clocks  and  watches,  of  guns,  of  locks 
and  ironmongery,  of  lamps  and  gas  apparatus,  and  a  multitude  of 
other  works,  possess,  in  each  case,  an  amount  of  skill  which  applies 
specifically  to  these  several  occupations ;  so  that  unless  the  works 
made  by  each  are  returned  to  the  absolute  makers  for  reparation, 
they  are  at,any  rate  sent  to  an  individual  engaged  in  the  same  line 
of  business. 


HISTORY   OF   ELECTRO-METALLURGY.  489 

Under  these  circumstances,  it  is  obvious  that  the  gun-makers, 
watchmakers,  and  others,  would  derive  little  or  no  advantage  from 
one  system  of  threads  prevailing  throughout  all  their  trades ;  in 
many  of  which,  as  before  noticed,  partial  systems  respectively 
adapted  to  them  already  exist.  The  means  employed  by  the  gen- 
erality of  artisans  in  matching  strange  threads,  are,  in  addition, 
entirely  independent  of  the  screw  lathe,  and  apply  equally  well  to 
all  threads,  whether  of  aliquot  measures  or  not ;  as  it  is  usual  to 
convert  one  of  the  given  screws,  if  it  be  of  steel,  into  a  tap,  or 
otherwise  to  file  a  screw  tool  to  the  same  pitch  by  hand,  wherewith 
to  strike  the  thread  of  the  screw  or  tap ;  and  when  several  screws 
are  wanted,  a  pair  of  dies  is  expressly  made. 

But  at  the  same  time  that,  from  manifold  considerations,  it  ap- 
pears to  be  quite  unnecessary  to  interfere  with  so  many  existing 
arrangements  and  interests,  it  must  be  freely  admitted  that  advan- 
tage would  ultimately  accrue  from  making  all  new  screws  of  aliquot 
measures ;  and  which,  by  gradually  superseding  the  old  irregular 
threads,  would  tend  eventually,  although  slowly,  to  introduce  a 
more  defined  and  systematic  arrangement  in  screw  tackle,  and  also 
to  improve  their  general  character. 


CHAPTER  XXIY. 

HISTORY   OF   THE   ART   OF   ELECTRO-METALLURGY. 

IN  reviewing  the  rise  and  progress  of  any  discovery  in  the  arts 
and  sciences,  particularly  of  one  connected  with  the  application  of 
chemistry  to  manufacturing  purposes,  there  are  two  circumstances 
which  almost  invariably  demand  especial  notice.  The  first  is,  that 
the  discovery  has  been  the  result  of  accidental  observation — a  fact 
eliminated  during  investigations  undertaken  for  other  purposes — 
rather  than  the  result  of  a  direct  endeavor  to  make  the  discovery. 
The  second  is,  that,  after  the  discovery  has  been  made  known,  it  is 
found  that  many  previously  published  experiments  exhibited  re- 
sults which  bore  more  or  less  directly  upon  the  subsequent  dis- 
covery, and  which  are  consequently  sometimes  cited  to  detract  from 
the  merit  of  the  discoverer,  and  the  originality  and  value  of  his 
discovery.  The  following  historical  sketch  will  show  that  these 
observations  directly  apply  to  the  discovery  of  the  art  of  Electro- 
Metallurgy  : 

VOLTA'S  DISCOVERY. — At  the  beginning  of  the  year  1800,  Pro- 
fessor Volta  invented  the  apparatus  which  has  been  named  after 
him,  the  Voltaic  Pile.  As  originally  constructed  by  Volta,  it  con- 
sisted of  an  equal  number  of  round  pieces  of  zinc,  silver,  and 
pasteboard — the  zinc  and  silver  pieces  being  each  about  the  size 


490 


THE   PRACTICAL    METAL-WORKERS   ASSISTANT. 


of  a  penny,  and  those  of  pasteboard  a  little  smaller;  the  paste- 
board pieces  were  soaked  in  a  solution  of  common  salt,  and  then 
with  the  metals  were  piled  in  the  following  manner : — zinc,  silver, 
pasteboard  ;  zinc,  silver,  pasteboard  ;  and  so  on,  in  the  same  order, 
till  all  the  pieces,  amounting  to  upwards  of  a  hundred,  were  piled 
upon  each  other,  the  uppermost  plate'  being  of  silver,  and,  as 
already  stated,  the  undermost  of  zinc;  these  exterior  plates,  to 
each  of  which  a  wire  is  attached,  form  the  terminals  or  poles  of 
the  pile.  Fig.  540  shows  the  construction  of  the  Pile. 

Fig.  540 


C— Silver  Plate. 

Z— Zinc  Plate. 

\v— Pasteboard  between. 

AA — The  Wires  in  connection  with 
the  Terminal  Plates. 


By  this  instrument  all  the  phenomena  of  an  ordinary  battery  can 
be  produced. 

CHEMICAL  DECOMPOSITIONS  BY  THE  PILE. — This  discovery' 
placed  in  the  hands  of  the  philosopher  an  instrument  by  which  he 
could  make  such  investigations  as  had  never  previously  been  con- 
ceived to  be  possible.  Nicholson,  for  example,  effected  the  decom- 
position of  water  and  of  several  metallic  salts :  and  observed,  as  a 
general  rule,  that  in  the  decomposition  of  the  latter  the  metal  of 
the  salt  was  reduced  upon  the  zinc  terminal  of  the  pile. 

FIRST  BATTERY.— -Cruikshanks,  of  Woolwich,  with  a  view  to 
facilitate  the  construction  of  the  pile,  employed  square  plates  of 
copper  and  zinc,  soldered  together  two  and  two;  these  were 
cemented,  by  means  of  pitch,  into  a  wooden  trough,  at  the  distance 
of  about  a  quarter  of  an  inch  from  each  other,  and  so  arranged 
that  the  zinc  plates  all  faced  one  end  of  the  trough,  and  the  copper 
plates  the  other  end.  The  spaces  or  cells  between  every  pair  of 
plates  were  filled  with  a  solution  of  common  salt,  or  a  mixture  of 
acid  and  water,  which  produced  the  same  effect  as  the  moist  cards 
in  the  pile.  The  trough  thus  charged  with  its  metals  and  solution 
acted  the  same  part  as  the  Voltaic  pile.  This  was  the  first  of 
those  instruments  now  so  well  known  as  the  "galvanic  battery" 

DECOMPOSITION  BY  THE  BATTERY,  AND  ITS  APPLICATION. — 
Cruikshanks  attached  a  silver  wire  to  each  terminal  of  his  battery, 


HISTORY   OF   ELECTRO-METALLURGY.  491 

and  the  other  ends  of  these  wires  he  placed  in  a  glass  tube.  When 
this  tube  was  filled  with  a  solution  of  acetate  of  lead,  and  the 
electric  current  was  allowed  to  pass  through  it  for  some  time,  me- 
tallic lead  was  found  deposited  upon  the  wire  attached  to  the  zinc 
terminal  of  the  battery.  Solutions  of  sulphate  of  copper,  nitrate 
of  silver,  and  several  other  salts,  were  tried  with  similar  resulte. 
The  metals,  as  Cruikshanks  expressed  it,  were  "  revived,"  and  that 
so  completely,  as  to  suggest  to  him  the  application  of  the  battery 
to  the  analysis  of  minerals.  While  Cruikshanks,  Nicholson,  and 
several  other  gentlemen  in  this  country  were  making  investiga- 
tions and  applications  of  voltaic  electricity,  upon  the  Continent, 
Brugnatelli,  Fourcroy,  Yauquelin,  and  Thenard  were  making 
similar  investigations,  and  obtaining  similar  results.* 

DEPOSITION  OF  METALS  UPON  OTHERS. — Brugnatelli,  in  his 
Annals  of  Chemistry,  gives  a  long  list  of  experiments  on  the  de- 
composition of  salts  by  the  pile.  He  observed  the  transfer  of  the 
elements  of  a  decomposed  compound  from  one  pole  to  another — 
that  silver,  when  deposited  upon  platinum,  preserved  all  its  metallic 
brightness — and  that,  when  copper  or  zinc  were  used  in  connec- 
tion with  the  silver  terminal,  or  positive  pole,  of  the  pile  for  decom- 
posing salts,  these  metals  were  dissolved,  and  deposited  upon  the 
negative  pole.  The  researches  of  Fourcroy,  Yauquelin,  and  Thenard 
gave  the  same  results. 

GILDING. — In  1805,  Brugnatelli,  in  a  letter  to  Yan  Mons,  men- 
tions, among  other  scientific  facts,  that  "he  had  gilt  in  a  complete 
manner  two  large  silver  medals,  by  bringing  them,  by  means  of  a 
steel  wire,  into  communication  with  the  negative  pole  of  a  voltaic 
pile,  and  keeping  them  one  after  the  other  immersed  in  ammoniuret 
of  gold  newly  made  and  well  saturated."f 

EARLY  OPINIONS  CONCERNING  ELECTRO-DECOMPOSITION. — The 
above  few  instances  are  selected  from  a  host  of  a  similar  kind  upon 
electro-decomposition,  to  show  that  the  fact  of  the  deposition  of 
metals  by  an  electric  current  was  familiar  to  philosophers  at  this 
early  stage  of  the  history  of  galvanism;  that  nevertheless,  the 
phenomenon  was  never  thought  of  further  than  as  a  curious 
action  of  electricity  when  passing  through  a  solution  containing 
metals ;  and  that  although  these  effects  were  produced  again  and 
again,  it  was  only  to  prove  and  enforce  certain  speculative  views 
respecting  the  electric  fluid.  As  for  example,  Brugnatelli  had 
formed  an  idea  that  the  electric  fluid  had  some  relations-  to  an  acid 
which  he  called  the  electric  acid,  and  he  therefore  viewed  the  decom- 
position of  solutions,  and  the  obtaining  of  the  metal,  which  he 
termed  an  electrate,  as  the  result  of  the  combination  of  this  electric 
acid  with  the  metal  of  the  solution.  In  one  of  his  memoirs  upon 
this  subject,  he  says — "  Gold  and  platinum  are  not  sensibly  altered 
by  the  electric  matter  which  passes  through  them,  though  it  often 

*  Wilkinson,  Elements  of  Galvanism,  vol.  ii.  1804. 
t  Phil.  Magazine,  1805. 


492  THE  PEACTICAL   METAL-WORKER' S   ASSISTANT. 

happens  that  the  electric  current  deposits  on  gold  a  stratum  of  zinc, 
copper,  mercury,  or  silver,  according  to  whichever  of  these  metallic 
bodies  it  traverses."*  In  the  same  paper  it  is  several  times  stated 
that  gold  and  platina  do  not  seem  sensibly  affected  by  the  electric 
acid.  And,  when  he  communicated  the  above  experiment  of  gild- 
ing the  two  medals,  his  object  was  to  show  that  he  had  now  found 
that  the  electric  acid  had  also  the  power  of  acting  upon  gold ;  and 
the  publication  of  these  results  and  observations  excited  no  other 
idea  in  the  minds  of  philosophers  of  that  period  than  that  they 
were  mere  scientific  curiosities.  The  editor  of  the  Philosophical 
Magazine  appended  the  following  note  to  the  extract  already 
quoted : — "  The  result  here  detailed  reminds  me  of  one,  somewhat 
similar,  which  took  place  during  some  experiments  performed 
some  years  ago  in  the  Askesian  Rooms.  Some  gold  leaf  was  put 
loose  upon  a  new  piece  of  copper  coin,  which  was  then  brought 
into  the  circuit  of  the  pile.  A  part  of  the  gold  was  inflamed,  and 
other  portions  adhered  to  the  surface  of  the  copper,  as  completely 
as  if  they  had  been  attached  by  any  common  gilding  process."f 

How  THESE  RESULTS  AFFECT  THE  DISCOVERY. — We  have  been 
particular  in  thus  noticing  the  observations  of  the  first  pioneers  in 
electro-chemistry,  because  these  and  similar  facts  of  later  date 
have  been  brought  prominently  forward  by  writers  upon  electro- 
metallurgy, with  the  apparent  intention  to  detract  from  the  merit 
due  to  the  discoverers  of  the  new  art ;  founding  their  objection  on 
the  ground  that  the  principle  upon  which  the  discovery  is  founded 
is  not  new.  "Electro-metallurgy,"  says  Mr.  Smee,  "may  be  said  to 
have  its  origin  in  the  discovery  of  the  constant  battery  by  Pro- 
fessor Daniell,  for  in  that  instrument  the  copper  is  continually 
reduced  upon  the  negative  plate."  And  again,  when  speaking  of 
Daniells'  battery,  he  says — "  Mr.  M.  De  la  Rue  experimented  on  its 
properties,  and  found  the  copper  plate  also  covered  with  a  coating 
of  metallic  copper,  which  is  continually  being  deposited ;  and  so 
perfect  is  the  sheet  of  copper  thus  formed,  that  being  stripped  off, 
it  has  the  counterparts  of  every  scratch  of  the  plate  on  which  it  is 
deposited."} 

Doubtless  these  experiments  border  very  closely  upon  the  dis- 
covery ;  but  yet  they  have  no  more  claim  to  serve  as  dates  to  its 
origin  than  those  we  have  been  referring  to.  But  if  it  be  neces- 
sary that  an  originating  experiment  must  have  a  resemblance  to 
that  which  it  suggests— suich  as  Daniell's  battery ;  and  the  single 
cell  of  electro-metallurgy—why  omit  to  refer  to  Dr.  Wollaston's 
earlier  experiments  of  1801  ?  He  says—"  If  a  piece  of  silver,  in 
connection  with  a  more  positive  metal,  be  put  into  a  solution  of 
copper,  the  silver  is  coated  over  with  the  copper,  which  coating 
will  stand  the  operation  of  burnishing."§  But  in  our  opinion  none 

*  Brugnatelli,  Annals  of  Chemistry,  vol.  xviii.,  and  Wilkinson,  vol.  ii. 

t  Phil.  Mag.,  1805. 

j  Smee,  Elements  of  Electro-Metallurgy,  2d  Edition   1843. 

I  Philosophical  Transactions,  ItOl. 


HISTORY   OF   ELECTKO -METALLURGY.  493 

of  these  results  originated  electro-metallurgy:  the  discovery  of  that 
art,  although  it  is  an  application  of  such  results  as  we  have  described, 
was  as  original  on  the  part  of  the  discoverers,  and  as  unconnected 
with  these  results  at  the  time  it  was  made,  as  it  would  have  been 
had  the  earlier  observations  never  been  published.  The  discovery 
seems  to  have  been  deduced  from  results  which  the  discoverers 
had  obtained  in  their  own  experiments,  not  even  while  searching 
for  such  a  discovery  but  during  investigations  instituted  for  other 
purposes. 

USE  OF  OBSERVED  FACTS. — It  must  not  be  supposed  that  we 
depreciate  the  value  of  the  published  facts  upon  the  decomposition 
of  salts,  nor  that  we  overlook  their  relation  to  the  discovery  which 
followed  ;  for  the  multiplication  of  facts,  and  the  improvement  of 
instruments  for  experimenting,  enlarge  our  knowledge  of  the  prin- 
ciples to  be  investigated  or  applied ;  they  facilitate  inquiry,  and 
increase  the  number  of  observers.  The  circumstances  connected 
with  the  discovery  of  ELECTRO-METALLURGY — of  the  application 
of  the  decomposing  force  of  an  electro  current  passing  through  a 
solution,  will  illustrate  these  observations. 

SPENCER'S  FIRST  EXPERIMENTS. — Mr.  Thomas  Spencer,  of  Liver- 
pool, states  that,  in  1837,  while  experimenting  with  a  modification 
of  a  Daniell's  battery,  he  used  a  penny  piece  instead  of  a  plain  piece 
of  copper,  as  a  pole.  Copper  was  deposited  from  the  solution  upon 
it,  and  on  removing  the  wire  which  attached  the  penny  to  the  zinc 
plate  he  also  pulled  off  a  portion  of  the  deposited  copper,  which  he 
found  to  be  an  exact  counterpart  or  mould  of  a  part  of  the  head  and 
letters  of  the  coin  as  smooth  and  sharp  as  the  original  But  this  did 
not  suggest  to  him  any  useful  application,  until  sometime  after  he 
dropped,  accidentally,  a  little  varnish  upon  a  slip  of  copper  which  he 
was  about  to  use  in  the  same  way  as  he  had  used  the  penny  piece. 
On  finding  that  no  deposit  of  copper  took  place  on  the  parts  where 
the  varnish  had  dropped,  he  then  conceived  the  idea  of  applying  this 
principle  to  the  arts,  by  coating  a  piece  of  copper  with  varnish  or 
wax,  and  cutting  a  design  through  the  wax  or  varnish,  leaving  the 
copper  bare,  and  then  depositing  upon  these  parts,  so  that  upon 
removing  the  varnish  the  design  would  be  left  in  relief. 

JACOBI'S  EXPERIMENTS. — While  Mr.  Spencer  was  following  up 
these  ideas,  the  following  paragraph  appeared  in  the  Athenseum  for 
4th  May,  1839 : 

"Galvanic  Engraving  in  Relief. — While  M.Daguerre  and  Mr.  Fox 
Talbot  have  been  dipping  their  pencils  in  the  solar  spectrum,  and 
astonishing  us  with  their  inventions,  it  appears  that  Professor 
Jacobi,  at  St.  Petersburgh,  has  also  made  a  discovery  which  prom- 
ises to  bo  of  little  less  importance  to  the  arts.  He  has  found  a 
method — if  we  understand  our  informant  rightly — of  converting 


disposal,  funds  to  enable  him  to  perfe 
In  consequence  of  this  announcement,  Mr.  Spencer,  on  the  8th 


494  THE  PEACTICAL   METAL-WOEKEB's  ASSISTANT. 

of  May,  1839,  gave  notice  to  the  Liverpool  Polytechnic  Institution, 
that  he  should  make  a  communication  to  them  of  his  process  for 
effecting  results  similar  to  those  of  Professor  Jacobi.  But  Mi. 
Spencer  appears  to  have  changed  his  design  of  reading  it  to  the 
above  Institution,  in  order  to  have  it  read  at  the  meeting,  of  the 
British  Association,  which  was  to  take  place  a  short  time  after. 

JOEDAN'S  EXPEEIMENTS. — Meanwhile  the  announcement  of  the 
Athenseum  was  quoted  in  the  London  Mechanics'  Magazine  for  May 
llth,  1839,  which  brought  forth  a  letter  from  Mr.  C.  J.  Jordan,  a 
book-printer,  dated  22d  May,  1839,  and  published  on  the  8th  June 
of  the  same  year  in  the  London  Mechanics'  Magazine.  In  this  letter 
Mr.  Jordan  describes  his  experiments  upon  the  same  subject,  detail- 
ing the  method  of  procuring  electrotypes,  and  offering  hints  for 
their  application  which  have  since  been  acted  upon  with  considera- 
ble success.  The  following  is  a  copy  of  Mr.  Jordan's  letter,  which 
was,  no  doubt,  the  first  published  description  of  the  art  in  this 
country : 

"Engraving  by.  Galvanism. 

"  Sir : — Observing  in  the  last  page  of  a  recent  Number  of  your 
Magazine,  a  notice  extracted  from  the  Athenaeum,  relative  to  a  dis- 
covery of  Professor  Jacobi,  its  perusal  occasioned  the  recollection 
of  some  experiments  performed  about  the  commencement  of  last 
summer,  with  the  view  of  obtaining  impressions  from  engraved 
copper  plates,  by  the  aid  of  galvanism,  which  led  me  to  infer  some 
analogy  in  principle  with  those  of  the  Eussian  Professor,  and  may 
probably  give  me  the  right  to  claim  priority  in  its  discovery  and 
application.  These  experiments  were  abandoned  from  the  want  of 
that  most  important  element  in  pursuits  of  this  nature— time ;  the 
writer's  share  of  the  said  element  being  occupied  in  a  manner  more 
imperative  than  pleasing.  I  regret,  however,  not  having  made  it 
the  subject  of  an  earlier  communication,  as  this  would  have  placed 
my  pretensions  beyond  doubt;  but,  inasmuch  as  the  notice  alluded 
to  is  given  from  memory,  and  is  undescriptive,  while  I  may  be 
enabled  to  exhibit  the  modus  operandi,  my  assertion  may  be  at 
least  partially  substantiated. 

"  It  is  well  known  to  experimentalists  on  the  chemical  action  of 
voltaic  electricity,  that  solutions  of  several  metallic  salts  are  decom- 
posed by  its  agency,  and  the  metal  procured  in  a  free  state.  Such 
results  are  very  conspicuous  with  copper  salts,  which  metal  may  be 
obtained  from  its  sulphate  (blue  vitriol),  by  simply  immersing  the 
poles  of  a  galvanic  battery  in  its  solution,  the  positive  wire  becoming 
gradually  coated  with  copper.  This  phenomenon  of  metallic  reduc- 
tion is  an  essential  feature  in  the  action  of  sustaining  batteries,  the 
effect,  in  this  case,  taking  place  on  more  extensive  surfaces.  But 
the  form  of  voltaic  apparatus  which  exhibits  this  result  in  the  most 
interesting  manner,  and  relates  more  immediately  to  the  subject  of 
the  present  communication,  may  be  thus  described: — It  consists  of 
a  glass  tube,  closed  at  one  extremity  with  a  plug  of  plaster  of  Paris, 


HISTORY   OF   ELECTRO- METALLURGY.  495 

and  nearly  filled^with  a  solution  of  sulphate  of  copper ;  this  tube 
and  its  contents  are  immersed  in  a  solution  of  common  salt.  A  plate 
of  copper  is  placed  in  the  first  solution,  and  is  connected,  by  means 
of  a  wire  and  solder,  with  a  zinc  plate  which  dips  into  the  latter. 
A  slow  electric  action  is  thus  established  through  the  pores  of  the 
plaster,  which  it  is  not  necessary  to  mention  here — the  result  of 
which  is  the  precipitation  of  minutely  crystallized  copper  on  the 
plate  of  that  metal,  in  a  state  of  greater  or  less  malleability  accord- 
ing to  the  slowness  or  rapidity  with  which  it  is  deposited.  In 
some  experiments  of  this  nature,  on  removing  the  copper  thus 
formed,  I  remarked  that  the  surface  in  contact  with  the  plate 
equalled  the  latter  in  smoothness  and  polish,  and  mentioned  this 
fact  to  some  individuals  of  my  acquaintance.  It  occurred  to 
me,  therefore,  that  if  the  surface  of  the  plate  was  engraved,  an 
impression  might  be  obtained.  This  was  found  to  be  the  case ; 
for,  on  detaching  the  precipitated  metal,  the  most  delicate  and 
superficial  markings,  from  the  fine  particles  of  powder  used  in 
polishing,  to  the  deeper  touches  of  a  needle  or  a  graver,  exhibited 
their  correspondent  impressions  in  relief,  with  great  fidelity.  It 
is,  therefore,  evident  that  this  principle  will  admit  of  improvement, 
and  that  casts  and  moulds  may  be  obtained  from  any  form  of 
copper. 

"  This  rendered  it  probable  that  impressions  may  be  obtained 
from  those  other  metals  having  an  electro-negative  relation  to  the 
zinc  plate  of  the  battery.  With  this  view,  a  common  printing- 
type  was  substituted  for  the  copper  plate,  and  treated  in  the  same 
manner.  This  also  was  successful ;  the  reduced  copper  coated  that 
portion  of  the  type  immersed  in  the  solution.  This,  when  re- 
moved, was  found  to  be  a  perfect  matrix,  and  might  be  employed 
for  the  purpose  of  casting,  where  time  is  not  an  object. 

It  appears,  therefore,  that  this  discovery  may  be  turned  to  some 
practical  account.  It  may  be  taken  advantage  of  in  procuring 
casts  from  various  metals,  as  above  alluded  to;  for  instance,  a 
copper  die  may  be  formed  from  a  cast  of  a  coin  or  medal,  in  silver, 
type  metal,  or  lead,  etc.,  which  may  be  employed  in  striking  im- 
pressions in  soft  metals.  Casts  may  probably  be  obtained  from  a 
plaster  surface  surrounding  a  plate  of  copper ;  tubes  or  any  small 
vessels  may  also  be  made  by  precipitating  the  metal  around  a  wire, 
or  any  kind  of  surface,  to  form  the  interior,  which  may  be  removed 
mechanically,  by  the  aid  of  an  acid  sblvent,  or  by  heat. 

"  C.  J.  JORDAN." 

"  To  the  Editor  of  the  London  Mechanics'  Magazine." 

Clear  and  perspicuous  as  this  letter  is,  it  did  not  attract  the 
slightest  notice.  And  a  few  weeks  after,  we  find  that  its  existence 
was  forgotten  even  by  the  editor  of  the  magazine  in  which  it 
appeared. 

SPENCER'S  FIRST  PRINTED  PAPER  UPON  ELECTROTYPE. — Mr. 
Spencer's  communication,  referred  to  above,  was,  in  consequence 


496  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

of  some  misunderstanding,  not  read  at  the  meeting  of  the  British 
Association,  but  it  was  immediately  afterwards  read  before  the 
Polytechnic  Institution  of  Liverpool,  at  their  meeting  on  the  13th 
September,  1839,  which  was  upwards  of  three  months  after  the 
publication  of  Mr.  Jordan's  letter  in  the  London  Mechanics'  Maga- 
zine. Mr.  Spencer's  paper  was  accompanied  with  specimens  both 
of  electrotypes  and  of  printing  from  electrotypes.  The  publica- 
tion of  this  paper  acted  like  an  electric  shock  upon  society,  and 
men  both  of  science  and  art  became  active  competitors  in  this  new 
field  of  application ;  the  one  class  anxious  to  bear  away  the  honors 
arising  from  some  important  improvement ;  the  other,  the  profits 
which  might  follow  some  novel  application  of  the  process  to  their 
own  or  some  other  branch  of  manufacture.  Indeed,  thousands  of 
all  classes  and  ages,  who  had  never  previously  given  science  a 
passing  thought,  became  fascinated  with  the  new  art,  and — the 
process  being  simple  and  easy  to  perform — the  amateurs  soon  be- 
came excellent  electrotypists.  With  these  combined  efforts,  it 
need  not  be  wondered  at  that  in  a  very  short  time  improvements 
of  great  scientific  interest  were  pointed  out,  and  applications  of  the 
greatest  importance  to  the  arts  and  manufactures  of  this  country 
were  introduced.  In  consequence,  some  of  our  old  and  standard 
manufactures,  as  we  shall  subsequently  have  occasion  to  notice  at 
some  length,  have  already  been  revolutionized. 

HISTORICAL  ANOMALY. — During  a  period  of  nearly  five  years 
— while  the  country  was  passing  through  an  electrotyping  mania 
— Mr.  Spencer  held  the  undivided  honor  of  being  the  first  to 
apply  the  deposition  of  metals  to  practical  purposes  in  this  coun- 
try, but  early  in  1844,  Mr.  Henry  Dircks,  in  a  letter  to  the  London 
Mechanics'  Magazine,  revived  Mr.  Jordan's  letter,  and  told  us  that 
he  was  aware  of  its  existence  from  the  time  of  its  first  publication. 
We  cannot  eulogise  either  the  policy,  or  the  love  of  scientific 
truth,  which  induced  Mr.  Dircks  to  remain  silent  so  long,  and  see 
the  claims  of  Mr.  Jordan  set  aside  by  one  whom  he  considered  to 
be  a  mere  pretender  to  the  merit  of  the  discovery.  Nor,  after  a 
careful  and  impartial  examination  of  all  the  details  published  on 
the  subject,  can  we  agree  to  his  condemnation  of  Mr.  Spencer's 
prior  claims ;  as  he,  Mr.  Spencer,  upon  the  8th  of  May,  as  already 
noticed,  stated  to  a  public  meeting  of  the  Polytechnic  Society  of 
Liverpool,  that  he  had  made  a  similar  discovery  previous  to 'any 
knowledge  of  either  what  Jordan  or  Jacobi  had  done,  and  which 
was  a  publication  as  much  as  if  printed  in  the  Times  or  Athenseum, 
and  especially  when  followed  by  a  detailed  description  of  the  dis- 
covery. 

It  is  to  be  regretted  that  Mr.  Jordan's  diffidence,  which  in  this 
case  was  far  from  being  commendable,  prevented  his  setting  the 
public  right  upon  this  important  matter.  As  a  consequence,  he 
must  now  be  content  with  a  much  smaller  share  of  the  honor  of 
the  discovery  than  he  might  have  enjoyed. 

CT*  reviewing  the  circumstances  of  this  discovery,  it  strikes  us 


HISTORY   OF   ELECTRO-METALLURGY.  497 

as  being  a  remarkable  instance  of  the  unity  of  intellectual  percep- 
tion in  reference  to  the  general  principles  of  Nature  and  their  ap- 
plications ;  for  we  believe  that  Professor  Jacobi,  Mr.  Spencer,  and 
Mr.  Jordan,  viewed  the  subject  of  electro  depositions  in  the  same 
light,  and  about  the  same  time  ;  and  each,  according  to  their  sev- 
eral abilities,  presented  to  the  public  the  same  discovery,  indepen- 
dent of  the  other,  excepting  the  announcement  made  by  one  having 
hastened  the  publication  of  the  observations  of  the  others. 

The  following  is  Mr.  Spencer's  original  paper  on  electro-metal- 
lurgy, which  we  give  at  length,  trusting  that  its  importance  in  con- 
nection with  the  history  of  the  art,  and  the  lucid  description  of  its 
practice,  will  serve  as  a  sufficient  apology  for  not  abridging  it : 

"  On  Working  in  Metal  by  Voltaic  Electricity,  reprinted  from  the  Pa- 
per Published  by  the  Liverpool  Polytechnic  Society,  and  read  at  the 
Meeting  of  September  the  Vlih,  1839,  Notice  being  given  May  the 
8th:  Henry  Booth,  Esq.,  President,  in  the  Chair. 

"  In  the  paper  that  I  have  the  honor  to  lay  before  the  society,  I 
do  not  profess  to  have  brought  forward  a  perfect  invention.  My 
only  object  is  to  point  out  a  means  by  which,  I  hope,  practical 
men  may  be  enabled  to  apply  a  great  and  universal  principle  of 
Nature  to  the  useful  and  ornamental  purposes  of  life.  In  this  I 
may  be  considered  sanguine — an  error,  I  am  aware,  too  often  fallen 
into  by  those  who,  like  myself,  imagine  they  have  discovered  a 
useful  application  of  an  important  principle ;  but  however  this 
may  fall  out,  I  shall  lay  an  account  of  its  results,  with  specimens, 
successful  and  unsuccessful,  before  the  members  and  the  public — 
previously  stating,  however,  that  all  my  first  experiments  were 
made  on  a  small  scale — a  method  of  procedure  attended  Avith  many 
advantages  to  the  experimentalist  himself,  but  having  its  disadvan- 
tage when  laid  before  the  public.  In  this  first  respect,  perhaps, 
the  chemical  experimenter  has  an  advantage  over  the  mechanical 
one,  as  the  success  of  his  experiment,  when  tried  on  a  small  scale, 
doubly  guarantees  it  if  conducted  on  a  still  larger  scale :  with 
mechanical  results  I  believe  in  most  instances  it  is  the  reverse.  But 
when  the  chemist  produces  his  microscopic  proofs,  the  public 
are  generally  slow  to  believe  that  such  minute  appearances  should 
warrant  him  in  coming  to  any  general  conclusion. 

"In  the  latter  part  of  September,  1837,  I  was  induced  to  make 
some  electro-chemical  experiments,  with  single  pairs  of  plates> 
consisting  of  small  pieces  of  zinc  and  equal-sized  pieces  of  copper,, 
connected  together  with  wires  of  the  latter  metal.  It  was  intended 
that  the  action  should  be  slow :  the  fluids  in  which  the  metallic 
electrodes  were  immersed  were  in  consequence  separated  by  thia 
discs  of  plaster  of  Paris.  In  one  cell  thus  formed  was  placed  sul- 
phate of  copper  in  solution — in  the  other,  a  weak  solution  of 
common  salt.  I  need  scarcely  add  thqrf,  the  copper  electrode  was 
placed  in  the  cupreous  solution,  the  other  being  in  that  of  the  salt. 
32 


498  THE   PRACTICAL   METAL-WORKER' S  ASSISTANT. 

I  mention  these  experiments  briefly — not  because  they  are  directly 
connected  with  what  I  shall  have  to  lay  before  the  society,  but 
because,  by  a  portion  of  their  results,  I  was  induced  to  come  to 
the  conclusions  I  have  done  in  the  following  paper.  I  was  desir- 
ous that  no  action  should  take  place  on  the  wires  by  which  the 
electrodes  were  held  together ;  and  to  attain  this  object  I  varnished 
them  with  sealing-wax  varnish :  but,  in  one  instance,  I  dropt  a 
portion  on  the  copper  electrode  that  was  attached.  I  thought 
nothing  of  this  circumstance  at  the  moment,  but  put  the  experi- 
ment in  action. 

"  This  operation  was  conducted  in  a  glass  vessel ;  I  had  conse- 
quently an  opportunity  of  occasionally  examining  its  progress  from 
the  exterior.  After  the  lapse  of  a  few  days,  metallic  crystals  had 
covered  the  copper  electrode — with  the  exception  of  that  portion 
which  had  been  spotted  with  the  drops  of  varnish.  I  at  once  saw 
that  I  had  it  in  my  power  to  guide  the  metallic  deposition  in  any 
shape  or  form  I  chose,  by  a  corresponding  application  of  varnish 
or  other  non-metallic  substance. 

"  I  had  been  aware  of  what  every  one  who  uses  a  sustaining 
galvanic  battery  with  sulphate  of  copper  in  solution  must  know — 
that  the  copper  plates  acquire  a  coating  of  copper  from  the  action 
of  the  battery ;  but  I  had  never  thought  of  applying  it  to  a  useful 
purpose,  except  to  multiply  the  plates  of  a  species  of  battery, 
which  I  did  in  1836.  My  present  attempt  was  with  a  piece  of  thin 
copper  plate,  having  about  four  inches  of  superfices,  with  an  equal 
sized  piece  of  zinc,  connected  as  before  by  a  piece  of  copper  wire. 
I  gave  the  copper  a  coating  of  soft  cement,  consisting  of  beeswax, 
resin,  and  a  red  earth.  It  was  compounded  in  the  manner  recom- 
mended by  Dr.  Faraday,  in  his  work  on  Chemical  Manipulation, 
but  with  a  larger  proportion  of  wax.  The  plate  received  its  coat- 
ing while  hot.  When  it  was  cold,  I  scratched  the  initials  of  my 
name  rudely  on  the  plate,  taking  special  care  that  the  cement  was 
quite  removed  from  the  scratches,  that  the  copper  might  be  thor- 
oughly exposed.  This  was  put  in  action  in  a  cylindrical  glass 
vessel,  about  half  filled  with  a  saturated  solution  of  sulphate  of 
copper.  I  then  took  a  common  gas  glass,  similar  to  that  used  to 
envelope  an  argand  burner,  and  filled  one  end  of  it  with  plaster  of 
Paris,  to  the  depth  of  three-quarters  of  an  inch.  Into  this  I  put 
water,  adding  a  few  crystals  of  sulphate  of  soda  to  excite  action, 
the  plaster  of  Paris  acting  as  a  partition  to  separate  the  fluids,  but, 
at  the  same  time,  being  sufficiently  porous  to  allow  the  electro- 
chemical action  to  permeate  its  substance. 

"  I  now  bent  the  wire  in  such  a  manner  that  the  zinc  end  of  the 
arrangement  should  be  in  the  saline  solution,  while  the  copper 
end,  when  in  its  place,  should  be  in  the  cupreous  solution.  The 
gas  glass,  with  the  wire,  was  then  placed  in  the  vessel  containing 
the  sulphate  of  copper. 

"It  was  then  suffered  to  remain  at  rest,  when  in  a  few  hours  I 
perceived  that  action  had  commenced,  and  that  the  portion  of  the 


HISTORY   OF   ELECTRO- METALLURGY.  499 

copper  rendered  bare  by  the  scratches  had  become  gradually 
coated  with  pure  bright  deposited  metal,  whilst  all  the  surround- 
ing portions  were  not  at  all  acted  on.  I  now  saw  my  former  obser- 
vations realized;  but  whether  the  deposition  so  formed  would 
retain  its  hold  on  the  plate,  and  whether  it  would  be  of  sufficient 
solidity  or  strength  to  bear  working  if  applied  to  a  useful  pur- 
pose,' became  questions  which  I  now  determined  to  solve  by  experi- 
ment. It  also  became  a  question — should  I  be  successful  in  these 
two  points — whether  I  should  be  able  to  produce  lines  sufficiently 
in  relief  to  print  from.  This  latter  appeared  to  depend  entirely 
on  the  nature  of  the  cement  or  etching-ground  I  might  use. 

"  This  I  endeavored  to  solve  at  once ;  and,  I  may  state,  it  ap- 
peared at  the  time  to  be  the  main  difficulty,  as  my  impression  then 
was,  that  little  less  than  one-eighth  of  an  inch  of  relief  would  be 
requisite  to  print  from. 

"  I  now  procured  a  piece  of  copper,  and  gave  it  a  coating  of  a 
modification  of  the  cement  I  have  already  mentioned,  and  having 
covered  it  to  about  one-eighth  of  an  inch  in  thickness,  I  took  a  steel 
point  and  endeavored  to  draw  lines  in  the  form  of  net- work,  that 
should  entirely  penetrate  the  cement,  and  leave  the  surface  of  the 
copper  exposed.  But  in  this  I  experienced  much  difficulty,  from 
the  thickness  I  deemed  it  necessary  to  use ;  more  especially  when 
I  came  to  draw  the  cross  lines  of  the  net- work.  JThe  cement  being 
soft,  the  lines  were  pushed  as  it  were  into  each  other,  and  when  it 
was  made  of  harder  texture,  the  intervening  squares  of  the  net- 
work chipped  off  the  surface  of  the  metallic  plate.  However, 
those  that  remained  perfect  I  put  in  action  as  before. 

"In  the  progress  of  this  experiment  I  discovered  that  the  solidity 
of  the  metallic  deposition  depended  entirely  on  the  weakness  or 
intensity  of  the  electro-chemical  action,  which  I  knew  I  had  in  my 
power  to  regulate  at  pleasure,  by  the  thickness  of  the  intervening 
wall  of  plaster  of  Paris,  and  by  the  coarseness  or  fineness  of  the 
material.  I  made  three  similar  experiments,  altering  the  texture 
and  thickness  of  the  plaster  each  time,  by  which  I  ascertained  that 
if  the  partitions  were  thin  and  coarse,  the  metallic  depositions  pro- 
ceeded with  great  rapidity,  but  the  crystals  were  friable  and  easily 
separated ;  on  the  other  hand,  if  I  made  them  thicker  and  of  a  little 
finer  material,  the  action  was  slower,  but  the  metallic  deposition 
was  as  solid  and  ductile  as  copper  formed  by  the  usual  methods 
— indeed,  when  the  action  was  exceedingly  slow,  I  have  had  a 
metallic  deposition  apparently  much  harder  than  common  sheet 
copper,  but  more  brittle. 

"There  was  one  most  important  and,  to  me,  discouraging  circum- 
stance attending  these  experiments,  which  was,  that  when  I  heated 
the  plates  to  get  off  the  covering  of  cement,  the  meshes  of  copper 
net- work  occasionally  came  off  with  it.  I  at  one  time  imagined  this 
difficulty  inseparable,  as  it  appeared  that  I  had  cleared  the  cement 
entirely  from  the  surface  of  the  copper  that  I  meant  to  have  ex- 
posed ;  and  I  concluded  that  there  must  be  difference  in  the  mole- 


500  THE  PRACTICAL   METAL-WORKER'ri   ASSISTANT. 

cular  arrangement  of  copper  prepared  by  beat  and  that  prepared 
by  voltaic  action,  which  prevented  their  chemical  combination. 
However,  I  determined,  should  this  prove  so,  to  turn  it  to  account 
in  another  manner,  which  I  shall  relate  in  the  second  portion  of 
the  paper. 

''  I  now  occupied  myself  for  a  considerable  period  in  making 
experiments  on  this  latter  section  of  the  subject. 

"  In  one  of  them  I  found,  on  examination,  that  a  portion  of  the 
copper  deposition,  which  I  had  been  forming  on  the  surface  of  a 
coin,  adhered  so  strongly  that  I  was  quite  unable  to  get  it  off — 
indeed,  a  chemical  combination  had  apparently  taken  place.  This 
was  only  on  one  or  two  spots  on  the  prominent  parts  of  the  coin. 
I  immediately  recollected  that,  on  the  day  I  put  the  experiment  in 
action,  I  had  been  using  nitric  acid  for  another  purpose,  on  the 
table  I  was  operating  on,  and  that  in  all  probability  the  coin  might 
have  been  laid  down  where  a  few  drops  of  the  acid  had  accidentally 
fallen.  Bearing  this  in  view,  I  took  a  piece  of  copper,  coated  it 
with  cement,  made  a  few  scratches  on  its  surface  until  the  copper 
appeared,  and  immersed  it  for  a  short  time  in  dilute  nitric  acid, 
until  I  perceived,  by  an  elimination  of  nitrous  gas,  that  the  exposed 
portions  were  acted  upon  sufficiently  to  be  slightly  corroded.  I 
washed  the  copper  in  water,  and  put  it  in  action  as  before  described. 
In. forty-eight  hours  I  examined  it,  and  found  the  lines  were  en- 
tirely filled  with  copper,  I  applied  heat,  and  then  spirits  of  turpen- 
tine, to  get  off  the  cement,  and,  to  my  satisfaction,  I  found  that  the 
voltaic  copper  had  completely  combined  itself  with  the  sheet  on 
which  it  was  deposited. 

"  I  then  gave  a  plate  a  coating  of  cement  to  a  considerable  thick- 
ness, and  sent  it  to  an  engraver ;  but  when  it  was  returned  I  found 
the  lines  were  cleared  out  so  as  to  be  wedge-shaped,  or  somewhat 
in  the  form  of  a  V,  leaving  a  hair  line  of  the  copper  exposed  at 
the  bottom,  and  a  broad  space  near  the  surface ;  and  where  the 
turn  of  the  letters  took  place,  the  top  edges  of  the  lines  were 
galled  and  rendered  rugged  by  the.  action  of  the  graver.  This,  of 
course,  was  an  important  objection,  which  I  have  since  been  able  to 
remedy  in  some  degree  by  an  alteration  in  the  shape  of  the  graver, 
which  should  be  made  of  a  shape  more  resembling  a  narrow  par- 
allelogram than  those  in  cornrnon  use :  some  engravers  have  many 
of  their  tools  so  made.  I  diid  not  put  this  plate  in  action,  as  I  saw 
that  the  lines,  when  in  relief,  would  have  been  broad  at  the  top 
and  narrow  at  the  bottom.  I  took  another  plate,  gave  it  a  coating 
of  the  wax,  and  had  it  written  on  with  a  mere  point.  I  deposited 
copper  on  the  lines,  and  afterwards  had  it  printed  from.* 

"  I  now  considered  part  of  the  difficulties  removed :  the  prin- 
cipal one  yet  remaining  was  to  find  a  cement  or  etching-ground, 
the  texture  of  which  should  be  capable  of  being  cut  to  the  re- 

*  This  plate  was  shown  to  friends,  and  also  specimens  of  printing  from  it. 
in  1838. 


HISTORY   OF   ELECTRO-METALLURGY.  501 

quired  depth,  without  raising  what  is  technically  termed  a  burr, 
and,  at  the  same  time,  of  sufficient  toughness  to  adhere  to  the 
plate,  when  reduced  to  a  small  isolated  point,  which  would  neces- 
sarily occur  in  the  operation  which  wood-engravers  term  cross- 
hatching. 

"  I  have  since  learned,  from  practical  engravers,  that  much  less 
relief  .is  necessary  to  print  from  than  I  had  deemed  indispensable, 
and  that,  on  becoming  more  familiar  with  the  cutting  of  the  wax- 
cernent,  they  would  be  enabled  to  engrave  in  it  with  great  facility 
and  precision. 

"  I  tried  a  number  of  experiments  with  different  combinations 
of  wax,  resins,  varnishes,  earths,  and  metallic  oxides,  all  with  more 
or  less  success.  One  combination  that  exceeded  all  others  in  its 
texture  was  principally  composed  of  beeswax,  resin,  and  white 
lead.  This  had  nearly  every  requisite,  so  that  I  was  enabled  to 
polish  the  surface  of  the  plate  with  it  until  it  was  nearly  as  smooth 
as  a  plate  of  glass.  With  this  compound  I  had  two  plates,  five 
inches  by  seven,  coated  over,  and  portions  of  maps  cut  on  the 
cement,  which  I  had  intended  should  have  been  printed  off.  I  ap- 
plied the  same  process  to  these  as  to  the  others,  immersing  them 
into  dilute  nitric  acid  before  putting  them  in  action ;  indeed  I  suf- 
fered them  to  remain  about  ten  minutes  in  the  solution.  I  then  put 
them  into  the  voltaic  arrangement.  The  action  proceeded  slowly 
and  perfectly  for  a  few  days,  when  I  removed  them.  I  applied 
heat  as  usual,  to  remove  the  cement,  but  all  came  away,  as  in  a 
former  instance — the  voltaic  copper  peeling  off  the  plate  with  the 
greatest  facility.  I  was  much  puzzled  at  this  unexpected  result ; 
but,  on  cleaning  the  plate,  I  discovered  a  delicate  trace  of  lead,  ex- 
actly corresponding  to  the  lines  drawn  on  the  cement  previous  to 
the  immersion  in  the  dilute  acid.  The  cause  of  this  failure  was 
at  once  obvious :  the  carbonate  of  lead  I  had  used  to  compound 
the  etching-ground  had  been  decomposed  by  the  dilute  nitric  acid, 
and  the  metallic  lead  thus  reduced  had  deposited  itself  on  the- ex- 
posed portions  of  the  copper  plates,  preventing  the  voltaic  copper 
from  chemically  combining  with  the  sheet  copper.  I  was  now 
with  regret  obliged  to  give  up  this  compound,  and  to  adopt  another, 
consisting  of  beeswax,  common  resin,  and  a  small  portion  of 
plaster  of  Paris.  This  seems  to  answer  the  purpose  tolerably, 
though  I  have  no  doubt,  by  an  extended  practice,  a  better  may 
still  be  obtained  by  a  person  practically  acquainted  with  the  etch- 
ing-grounds in  use  among  engravers. 

"  I  now  proceed  to  the  second,  and  I  believe  the  most  satisfac- 
tory portion  of  the  subject.  Although  I  have  placed  these  experi- 
ments last,  some  of  them  were  made  at  the  same  time  with  the 
others  already  described,  and  some  of  them  before ;  but,  to  render 
the  subject  more  intelligible,  I  have  placed  them  thus. 

"  The  members  of  the  society  will  recollect  that,  on  the  first 
evening  it  met,  I  read  a  paper  on  the  '  production  of  metallic  veins 
in  the  crust  of  the  earth,'  and  that  among  other  specimens  of  cupre- 


502  THE   PRACTICAL   METAL -WORKERS   ASSISTANT. 

ous  crystallization  which  I  produced  on  that  occasion,  I  exhibited 
three  coins — one  wholly  covered  with  metallic  crystals,  the  other 
on  one  side  only.  It  was  used  under  the  following  circumstances. 
When  about  to  make  the  experiment,  I  had  not  a  slip  of  copper 
at  hand  to  form  the  negative  end  of  my  arrangement,  and,  as  a 
good  substitute,  I  took  a  penny  and  fastened  it  to  one  end  of  the 
wire,  and  put  it,  in  connection  with  a  piece  of  zinc,  in  thexapparatus 
already  described. 

"  Voltaic  action  took  place,  and  the  copper  coin  became  covered 
with  a  deposition  of  copper  in  a  crystalline  form.  But,  when 
about  to  make  another  experiment,  and  being  desirous  of  using 
the  piece  of  wire  used  in  the  first  instance,  I  pulled  it  off  the  coin 
to  which  it  was  attached.  In  doing  this,  a  piece  of  the  deposited 
copper  came  off  with  it ;  on  examining  the  under  portion  of  which, 
I  found  it  contained  an  exact  mould  of  a  part  of  the  head  and 
letters  of  the  coin,  as  smooth  and  sharp  in  every  respect  as  the 
original  on  which  it  was  deposited.  I  was  much  struck  with  this 
at  the  time ;  but,  on  examination,  the  deposition  metal  was  very 
brittle.  This,  and  the  fact  that  it  would  require  a  metallic  nucleus 
to  aggregate  on,  made  me  apprehensive  that  its  future  usefulness 
would  be  materially  abridged ;  but  it  was  reserved  for  future  ex- 
periment, and  in  consequence  laid  aside  for  a  time,  until  my  atten- 
tion was  recalled  to  the  subject  in  a  subsequent  experiment,  already 
detailed,  by  the  drops  of  varnish  on  a  slip  of  copper.  Finding  in 
that  instance  that  the  deposit  would  take  the  direction  of  any  non- 
conducting material,  and  be,  as  it  were,  guided  by  it,  I  was  induced 
to  give  the  previous  branch  of  the  subject  a  second  trial,  because 
I  had,  in  the  first  instance,  supposed  that  the  deposition  would 
only  take  place  continuously,  and  not  on  isolated  specks  of  a 
metallic  surface,  as  I  now  found  it  would ;  but  the  principal  in- 
ducement to  investigate  the  subject  was  the  fact  of  finding  that 
deposited  copper  had  much  more  tenacity  than  I  at  first  imagined. 

"  Being  aware  of  the  apparent  natural  law  which  limits  metallic 
deposition  by  voltaic  electricity,  excepting  in  the  presence  of  a 
metallic  body,  I  perceived  that  the  uses  of  the  process  would,  in 
consequence,  be  extremely  limited,  except  in  the  multiplication  of 
already  engraved  plates,  as,  whatever  ornament  it  might  produce, 
it  would  only  be  done  by  adhering  to  the  condition  of  a  metallic 
mould. 

"  I  accordingly  determined  to  make  an  experiment  on  a  very 
prominent  copper  medal.  It  was  placed  in  a  voltaic  circuit,  as 
already  described,  and  deposited  a  surface  of  copper  on  one  of  its 
sides  to  about  the  thickness  of  a  shilling.  I  then  proceeded  to  get 
the  deposition  off.  In  this  I  experienced  some  difficulty,  but  ulti- 
mately succeeded.  On  examination  with  a  lens,  every  line  was  as 
perfect  as  the  coin  from  which  it  was  taken.  I  was  then  induced 
to  use  the  same  piece  again,  and  let  it  remain  a  much  longer  time 
in  action,  that  I  might  have  a  thicker  and  more  substantial  mould, 
in  order  to  test  fairly  the  strength  of  the  metal.  It  was  accord- 


HISTORY   OF   ELECTRO-METALLURGY.  503 

ingly  put  again  in  action,  and  let  remain  until  it  had  acquired  a 
much  thicker  coating  of  the  metallic  deposition  ;  but  on  attempt- 
ing to  remove  it  from  the  medal  I  found  I  was  unable.  It  had, 
apparently,  completely  adhered  to  it. 

"I  had  often  practised,  with  some  degree  of  success,  a  method 
of  preventing  the  oxidation  of  polished  steel,  by  slightly  heating 
it  until  it  would  melt  fine  beeswax ;  it  was  then  wiped,  apparently 
completely  off,  but  the  pores  or  surface  of  the  metal  became  im- 
pregnated with  the  wax. 

"  I  thought  of  this  method,  and  applied  it  to  a  copper  coin. 

"  I  first  heated  it,  applied  wax,  and  then  wiped  it  so  completely 
off,  that  the  sharpness  of  the  coin  was  not  at  all  interfered  with.  I 
proceeded  as  before,  and  deposited  a  thick  coating  of  copper  on 
its  surface.  Being  desirous  to  take  it  off,  I  applied  the  heat  of  a 
spirit-lamp  to  the  back,  when  a  sharp  crackling  noise  took  place, 
and  I  had  the  satisfaction  of  perceiving  that  the  coin  was  com- 
pletely loosened.  In  short,  I  had  a  most  complete  and  perfect 
copper  mould  of  one  side  of  a  half-penny. 

"I  have  snuje  taken  some  impressions  from  the  mould  thus 
taken,  and,  by  adopting  the  above  method  with  the  wax,  they  are 
separated  with  the  greatest  ease. 

"  By  this  experiment  it  would  appear  that  the  wax  impregnates 
the.  surface  of  the  metal  to  an  inconsiderable  depth,  and  prevents 
a  chemical  adhesion  from  taking  place  on  the  two  surfaces ;  and  I 
can  only  account  for  the  crackling  noise,  on  separation,  by  suppos- 
ing it  probable  that  the  molecular  arrangement  of  the  voltaic 
metal  indifferent  from  that  subjected  to  percussion,  and  this  differ- 
ence causes  an  unequal  degree  of  expansibility  on  the  application 
of  heat. 

"  I  became  now  of  opinion,  that  this  latter  method  might  be 
applied  to  engraving  much  better  than  the  method  described  in 
the  first  portion  of  this  paper.  Having  found  in  a  former  experi- 
ment that  copper  in  a  voltaic  circuit  deposited  itself  on  lead  with 
as  much  rapidity  as  on  copper,  I  took  a  silver  coin,  and  put  it  be- 
tween two  pieces  of  clean  sheet-lead,  and  placed  them  under  a 
common  screw-press.  From  the  softness  of  the  lead,  I  had  a  com- 
plete and  sharp  mould  of  both  sides  of  the  coin,  without  sustain- 
ing injury.  I  then  took  a  piece  of  copper  wire,  soldered  the  lead 
to  one  end,  and  the  piece  of  zinc  to  the  other,  and  put  them  into 
the  voltaic  arrangement  I  have  already  described.  I  did  not,  in 
this  instance,  wax  the  mould,  as  I  felt  assured  that  the  deposited 
copper  would  easily  separate  from  the  lead  by  the  application  of 
heat,  from  the  different  expansibility  of  the  two  metals. 

"  In  this  result  I  was  not  disappointed.  When  the  heat  of  a 
spirit-lamp  was  applied  for  a  few  seconds  to  the  lead,  the  copper 
impression  carne  easily  off.  So  complete  do  I  think  this  latter 
portion  of  the  subject,  that  I  have  no  hesitation  in  asserting  that 
fac-similies  of  any  coin  or  medal,  no  matter  of  what  size,  may 
be  readily  taken,  and  as  sharp  as  the  original.  To  test  further  the 


50-i  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

capabilities  of  this  method,  I  took  a  piece  of  lead  plate,  and  stamped 
some  letters  of  its  surface  to  a  depth  sufficient  to  print  from,  when 
in  relief.  I  deposited  the  copper  on  it,  and  found  it  came  easily 
off,  the  letters  being  in  relief. 

"  Finding  from  this  experiment  that  the  extreme  softness  of  lead 
allowed  it  to  be  impressed  on  by  type  metal,  I  caused  a  small  por- 
tion of  ornamental  letter-press  to  be  set  up  in  type,  and  placing  it 
on'  a  planed  piece  of  sheet  lead,  it  was  subjected  to  the  action  of  a 
screw  press. 

"After  considerable  pressure,  it  was  found  that  a  perfectly  sharp 
mould  of  the  whole  had  been  obtained  in  the  lead.  A  wire  was 
now  soldered  to  it,  and  it  was  placed  in  an  apparatus  similar  in 
principle,  but  larger  than  the  one  already  described.  At  the  end 
of  eight  days  from  this  time,  copper  was  deposited  to  one-eighth  of 
an  inch  in  thickness  ;  it  was  then  removed  from  the  apparatus,  and 
the  rough  edges  of  the  deposited  copper  being  filed  off,  it  was  sub- 
jected to  heat,  when  the  two  metals  began  to  loosen.  The  separa- 
tion was  completed  by  inserting  a  piece  of  wedge-shaped  wood 
between  them. 

"  I  had  now  the  satisfaction  of  perceiving  that  I  had  by  these 
means  obtained  a  most  perfect  specimen  of  stereotyping  in  copper, 
which  had  only  to  be  mounted  on  a  wooden  block  to  be  ready  to 
print  from. 

"  From  the  successful  issue  of  this  experiment,  which  was  mainly 
due  to  the  susceptibility  of  the  lead,  I  was  induced  to  attempt  to 
copy  a  wood  engraving  by  a  similar  method,  provided  the  wood 
would  bear  the  requisite  pressure.  Knowing  that  wood  engrav- 
ings are  executed  on  the  end  of  the  block,  I  had  better  hopes  of 
succeeding,  the  wood  being  less  likely  to  sustain  injury. 

"  I  accordingly  procured  a  small  wood  block,  and  placed  its  en- 
graved surface  in  contact  with  a  piece  of  sheet  lead  made  very  clean, 
and  subjected  it  to  pressure,  as  in  the  former  instance.  I  had  now, 
as  before,  the  gratification  of  perceiving  that  a  perfect  mould  of  the 
little  block  had  been  obtained,  and  no  injury  done  to  the  original. 
Several  wood  engravings  and  copperplates  were  subjected  to  similar 
treatment,  and  are  now  in  process  of  being  deposited  on  in  the 
apparatus  before  me. 

"I  now  come  to  the  third  and  concluding  portion  of  the  experi- 
ments on  this  subject.  The  object  being  to  deposit  a  metallic  sur- 
face on  a  model  of  clay,  wood,  or  other  ?wn-metallic  body — as, 
otherwise,  I  imagined  the  application  of  this  principle  would  be 
extremely  limited.  Many  experiments  were  made  to  attain  this 
result,  which  I  shall  not  detail,  but  content  myself  with  describing 
those  which  were  ultimately  most  successful. 

"  I  procured  two  models  of  an  ornament,  one  made  of  clay,  and 
the  other  of  plaster  of  Paris,  soaked  them  for  some  time  in  linseed- 
oil,  took  them  out,  and  suffered  them  to  dry — first  getting  the  oil 
clean  off  the  surface.  When  dry,  I  gave  them  a  thin  coat  of  mastic 
varnish.  When  the  varnish  was  nearly  dry,  but  not  thoroughly  so,  I 


HISTORY   OF   ELECTRO-METALLURGY.  505 

sprinkled  some  bronze  powder  on  that  portion  I  wished  to  make  a 
mould  of.  This  powder  is  principally  composed  of  mercury  and 
sulphur,  or  it  may  be  chemically  termed  a  suLphuret  of  mercury. 
There  is  a  sort  that  acts  much  better,  in  which  is  a  portion  of  gold. 
I  had,  however,  a  complete  metalliferous  coating  on  the  surface 
of  the  model,  by  which  I  was  enabled  to  deposit  a  surface  of  cop- 
per on  it,  by  the  voltaic  method  I  have  already  described.  I  have 
also  gilt  the  surface  of  a  clay  model  with  gold  leaf,  and  have  been 
successful  in  depositing  copper  on  its  surface.  There  is  likewise 
another,  and  as  I  trust  it  will  prove,  a  simpler  method  of  attaining 
this  object ;  but  as  I  have  not  yet  sufficiently  tested  it  by  experiment, 
I  shall  take  another  opportunity  of  describing  it." 

[At  the  close  of  the  paper,  several  specimens  of  coins,  medals,  and 
copper  plates,  some  of  them  in  the  act  of  formation  by  the  voltaic 
process,  were  exhibited  by  Mr.  Spencer  to  the  Society.] 


PLUMBAGO  AS  A  COATING. — Shortly  after  Mr.  Spencer's  paper 
was  published,  several  important  improvements  were  introduced, 
one  or  two  of  which  we  will  refer  to  here,  and  will  give  the  others 
when  detailing  the  processes  to  which  the  improvements  were  ap- 
plied. The  first  was  the  use  of  plumbago  or  black  lead,  to  give 
the  surface  of  non-metallic  bodies  a  conducting  property.  This 
was  the  discovery  of  Mr.  Eobert  Murray,  a  gentleman  of  high  at- 
tainments and  unassuming  manners,  who  communicated  the  process 
to  the  members  of  the  Koyal  Institution  orally.  The  Society  of 
Arts  afterwards  awarded  to  Mr.  Murray  a  silver  medal,  as  an  ex- 
pression of  their  sense  of  the  value  of  the  discovery.  Seldom  was 
reward  more  deserving,  or  a  discovery  more  important  to  the  pur- 
poses to  which  it  was  to  be  applied,  for  this  application  at  once 
freed  electro-metallurgy  from  every  bond:  it  was  no  longer  necess- 
ary to  use  either  metallic  moulds,  or  moulds  having  metal  reduced 
upon  their  surfaces  by  chemical  means — which,  according  to  the 
processes  then  known,  was  both  tedious  and  uncertain,  and  only 
applicable  to  certain  substances.  Plumbago  possessed  all  the  re- 
quisite properties :  it  was  convenient,  plentiful,  and  cheap,  easily 
applied,  and  equally  effective  for  every  substance  on  which  the 
electrotypist  desired  to  obtain  a  deposit,  or  which  he  could  wish  to 
cover  with  metal,  either  for  useful  or  ornamental  purposes. 

SEPARATE  BATTERY. — The  second  improvement  to  be  noticed  is 
one  that  must  have  followed  the  original  discovery  very  soon,  namely, 
the  application  of  a  separate  battery  for  the  purposes  of  deposition. 
This  was  suggested  by  Mr.  Mason.  Although  those  instances  of 
deposition  of  metals  which  have  been  referred  to  in  the  early  history 
of  galvanism  were  effected  by  means  of  separate  batteries,  namely, 
by  placing  the  ends  of  the  wires  attached  to  the  terminals  of  the 
battery  in  the  solution  to  be  decomposed,  still  the  discovery  under 


506 


THE   PRACTICAL   METAL-WORKEB'S   ASSISTANT. 


Fig.  541. 


consideration  was  made  by  means  of  what  is  termed  the  single  cell. 
It  consisted  in  simply  attaching  by  a  wire  the  article  upon  which 
a  deposition  was  to  be  made  to  a  piece  of  zinc,  and  immersing  the 
zinc  in  diluted  acid,  and  the  other  article  in  a  solution  of  the  metal 
to  be  deposited ;  the  two  liquids  being  separated  by  a  porous  par- 
tition, or  diaphragm,  such  as  moist  bladder,  or  unglazed  porcelain. 
In  this  case,  the  whole  electricity  was  expended  within  the  cell,  to 
deposit  the  metal  within  or  upon  the  mould.  By  Mr.  Mason's  dis- 
covery, the  electricity  generated  in  the  cell  could  be  made  to  do  an 
equivalent  of  work  in  a  separate  cell  as  well — making  the  original 
arrangement  the  generating  cell  or  battery  to  the  second  cell.  In 
this  last  cell  was  also  a  solution  of  a  metal  having  in  it  a  sheet  of 
similar  metal  attached  to  the  copper  of  the  first  cell,  and  the  mould 
to  be  covered  was  attached  to  the  zinc  of  the  first  cell.  Fig.  541 
is  an  illustration  of  Mason's  improvement,  which  consisted  in  caus- 
ing a  medal,  in  the  act  of  being  deposited,  to  serve  as  part  of  a 
battery  for  the  deposition  of  another  medal. 

o2,  Outer  vessel  filled  with  sulphate  of  copper ;  o1,  another  ves- 
sel, with  P,  a  porous  cell  filled  with  dilute  acid,  in  which  is  placed 
z,  a  zinc  plate,  which  is  connected  by  a  wire  with  a  medal  m!  in 
the  second  vessel  charged  with  sul- 
phate of  copper.  The  medal,  m,  in 
the  first  cell,  is  connected  by  a  wire 
to  a  piece  of  copper,  c,  in  the  second 
cell :  the  electricity  passes  from  the 
zinc  z  to  m,  and  by  the  wire  to  c, 
then  to  m',  and  by  the  wire  back  to 
the  zinc  z. 

The  use  of  a  separate  battery,  how- 
ever self-evident,  was  a  valuable  ad- 
dition to  the  electro-metallurgist  for 
many  of  his  operations;  although 
for  some  purposes  the  original  single 
cell  is  to  be  preferred. 
LAWS  OF  DEPOSITION. — As  might  have  been  expected  in  the 
excitement  occasioned  by  the  announcement  of  a  new  art,  every 
individual  experimenter  became  so  engrossed  by  his  own  investi- 
gations and  their  results,  as  to  overlook  the  labors  of  others,  and 
at  last  to  lay  claim  to  the  honor  of  originating  all  the  discoveries 
they  announced;  while  the  truth  is,  that  nearly  "all  the  important 
facts  of  electro-metallurgy  appear  to  have  occurred  almost  simul- 
taneously to  various  experimenters.  We  shall  quote  one  or  two 
instances  of  these  absorbing  claims,  as  it  is  important  to  rectify  the 
errors  they  contain,  because  no  successful  laborer,  however  humble, 
in  the  field  of  science  or  art,  should  be  overlooked  by  his  fellow- 
laborer  whose  opportunities  for  research  may  be  much  more  favor- 
able. 


HISTORY   OF   ELECTRO-METALLURGY. 


507 


Extract  from  Sinews  "Electro-Metallurgy" 

"The  laws  regulating  the  reduction  of  all  metals  in  different 
states  were  first  given  in  this  work  as  the  result  of  my  own  dis- 
coveries. By  these  we  can  throw  down  gold,  silver,  platinum,  pal- 
ladium, copper,  iron,  and  almost  all  other  metals,  in  three  states, 
namely,  as  a  black  powder,  as  a  crystalline  deposit,  or  as  a  flexible 
plate.  These  laws  appear  to  me  at  once  to  raise  the  isolated  facts 
known  as  the  electrotype  into  a  science,  and  to  add  electro-metal- 
lurgy as  an  auxiliary  to  the  noble  arts  of  this  country." 

That  Mr.  Smee  discovered  the  laws  referred  to  we  have  not  the 
slightest  doubt :  they  were  published  as  laws  in  his  book,  and  they 
are  commonly  quoted  as  Mr.  Smee's ;  nevertheless,  he  was  not  the 
first  who  discovered  them ;  the  same  laws  were  pointed  out  by 
Mr.  Spencer,  in  his  original  paper  just  quoted,  published  eighteen 
months  previously  to  the  appearance  of  Mr.  Smee's  work,  as  will 
be  seen  from  the  following  extracts : 


Laws  given  by  Spencer. 
"I  discovered  that  the  solidity 
of  the  metallic  deposition  de- 
pended entirely  on  the  weakness 
or  intensity  of  the  electro-chem- 
ical action,  which  I  knew  I  had 
in  my  power  to  regulate  at 
pleasure,  by  the  thickness  of  the 
intervening  wall  of  plaster  of 
Paris,  and  by  the  coarseness  or 
fineness  of  the  material.  I  made 
three  similar  experiments,  alter- 
ing the  texture  and  thickness 
each  time,  by  which  I  ascer- 
tained, that  if  the  partitions  were 
thin  and  coarse,  the  metallic  de- 
position proceeded  with  great 
rapidity,  but  the  crystals  were 
friable  and  easily  separated ;  on 
the  other  hand,  if  I  made  them 
thicker,  and  of  a  little  finer  ma- 
terial, the  action  was  slower,  but 
the  metallic  deposition  was  as 
solid  and  ductile  as  copper  formed 
by  the  usual  methods.  Indeed, 
when  the  action  was  exceedingly 
slow,  I  have  had  a  metallic  depo- 
sition much  harder  than  common 
sheet  copper,  but  more  brittle." 

The  identity  of  these  deductions  or  laws  requires  no  comment ; 
and,  comparing  the  circumstances  of  the  one  having  nothing  but 


Laws  given  by  Smee. 
"Law  I. — The  metals  are  in- 
variably thrown  down  as  a  black 
powder,  when  the  current  of 
electricity  is  so  strong,  in  rela- 
tion to  the  strength  of  the  solu- 
tion, that  hydrogen  is  evolved 
from  the  negative  plate  of  the 
decomposition  cell. 

"Law  II.  —  Every  metal  is 
thrown  down  in  a  crystalline 
state,  when  there  is  no  evolution 
of  gas  from  the  negative  plate, 
or  no  tendency  thereto, 

"Law  III.  —  Metals  are  re- 
duced in  the  reguline  state,  when 
the  quantity  of  electricity,  in 
relation  to  the  strength  of  the 
solution,  is  insufficient  to  cause 
the  production  of  hydrogen  in 
the  negative  plate  of  the  decom- 
position trough,  and  yet  the  quan- 
tity of  electricity  very  'nearly 
suffices  to  induce  that  phenom- 
enon." 


508  THE   PRACTICAL   METAL-WOEKER'S   ASSISTANT. 

the  rude  apparatus  of  a  new-born  art  suggested  by  himself,  to  that 
of  the  other,  enjoying  the  advantage  of  eighteen  months  improve- 
ments, Mr.  Spencer  is  astonishingly  correct,  and  his  name  should 
be  identified  with  the  discovery  of  these  laws.  The  claim  of  origi- 
nality involved  in  the  inference  drawn  by  Mr.  Smee,  though  for- 
midable at  first  sight,  is  nevertheless,  without  foundation.  Mr. 
Smee  says :  "  These  laws  appear  to  me  at  once  to  raise  the  isolated 
facts  known  as  the  electrotype  into  a  science,  and  to  add  electro- 
metallurgy as  an  auxiliary  to  the  noble  arts  of  this  country"  Unfor- 
tunately for  the  validity  of  Mr.  Smee's  claim,  patents  were  taken 
out  long  previous,  both  in  England  and  France,  for  the  applica- 
tion of  the  electro-depositions  to  the  arts.  And  Messrs.  Elkington's 
patent  for  silvering  and  gilding  by  this  process — a  patent  which 
has  not  yet  been  superseded — was  not  only  published  in  full  detail, 
but  was  in  extensive  operation  months  before  the  publication  of 
Mr.  Smee's  book.  Nevertheless,  the  publication  of  Mr.  Smee's 
book  did  good  service  to  the  art  of  electrotyping ;  and  the  inven- 
tion of  his  battery  has  so  identified  his  name  with  the  science,  that 
it  will  go  down  to  posterity  as  that  of  an  active  and  successful 
laborer  in  the  field  of  electricity :  to  Mr.  Smee  we  owe,  moreover, 
the  very  appropriate  name  for  the  art,  Electro-metallurgy. 

WORKS  PUBLISHED  ON  ELECTRO-METALLURGY. — Besides  many 
interesting  papers  in  journals  and  magazines,  several  separate  works 
were  published  on  this  art.  Some  months  previously  to  the  publi- 
cation of  Mr.  Smee's  work,  Mr.  Spencer  had  given  the  world  "In- 
structions for  the  multiplication  of  works  of  art  in  metal  by  voltaic 
electricity;"  and  shortly  after  Mr.  Smee's  work  appeared,  we  had,  in 
rapid  succession,  Walker's  Electrotype  Manipulation,  Sturgeon's  Art 
of  Ekctrotyping,  Shaw's  Manual  of  Ekctro-metallurgy,  etc.,  all  show- 
ing much  practical  knowledge  of  the  subject.  Walker's  Manipu 
lation,  from  its  practical  nature  and  its  concise  form,  became  the 
favorite  of  the  amateur,  and  did  more  to  popularize  the  art  than  all 
the  others  put  together ;  and  although  little  pretensions  were  made 
to  originality,  the  author  will  not  fail  to  have  an  honorable  remem- 
brance in  the  history  of  the  art. 

PATENTS  TAKEN  OUT  FOR  ELECTRO-METALLURGY.— The  applica- 
tion of  the  art  to  useful  purposes  was  so  self-evident  and  so  eagerly 
sought  after,  that  no  less  than  ten  patents  were  taken  out  for  useful 
applications,  between  the  discovery  of  the  art  and  the  close  of  1841 ; 
and  not  a  year  has  passed  since,  without  adding  patents  for  certain 
improvements,  and  applications  of  Electro-metallurgy  to  some  par- 
ticular branch  of  manufacture,  several  of  which  will  be  noticed  in 
their  proper  places,  as  many  of  them,  although  based  upon  right 
principles,  were  commercially  speaking,  entire  failures. 


DESCRIPTION  OF   GALVANIC  BATTERIES.  509 


CHAPTER  XXV-. 

DESCRIPTION    OF    GALVANIC    BATTERIES,    AND    THEIR    RESPECTIVE 
PECULIARITIES. 

NOMENCLATURE. — The  terms  that  are  employed  to  denote  the 
various  parts  of  a  galvanic  battery,  and  of  other  electrotype  arrange- 
ments, frequently  puzzle  the  student,  and  lead  him  into  difficulties. 
Before  we  proceed  to  describe  the  various  forms  of  the. battery,  we 
shall,  for  this  reason,  give  a  preliminary  account  of  the  nomencla 
ture  of  galvanism. 

The  two  extremities  of  a  battery  have  long  been  called  Poles — 
one  of  them  the  Positive,  and  the  other  the  Negative,  Pole.  But 
objections  have  been  taken  to  the  use  of  the  terms  negative,  positive, 
and  pole,  on  the  ground  that  such  terms  do  not  convey  a  correct 
idea  of  the  circumstances  or  of  the  effects  produced.  Before  con- 
necting the  two  metals  or  extremities  of  a  battery,  there  is  no  elec- 
tricity evolved,  nor  is  there  any  electrical  tension  on  any  part  of 
the  arrangement ;  and  when  the  connection  is  formed  the  electricity 
simply  makes  a  circuit,  it  is  therefore  supposed  that  no  particular 
portion  of  that  circuit  can  be  said  to  be  either  negative  or  positive 
to  another  portion. 

PROPOSED  TERMS. — Various  terms  have  been  suggested  as  sub- 
stitutes for  negative  and  positive,  and-  also  for  pole.  Dr.  Faraday 
has  proposed  the  following :  for  pole,  he  substitutes  electrode,  which 
signifies  a  way;  for  the  negative  pole,  cathode,  signifying  downwards; 
and  for  the  positive  pole,  anode  or  upwards.  To  understand  these 
terms  properly,  we  must  suppose  a  battery  lying  upon  the  ground 
with  its  copper  (positive)  end  to  the  east,  and  the  wire  connecting 
the  ends  of  the  battery  bent  into  an  arch  similar  to  the  course  of 
the  sun ;  the  electric  current  will  thus  flow  up  from  the  east  end  of 
the  battery,  and  descend  into  ft  at  the  west  end.  The  fluid  that  is 
decomposed  by  a  current  of  electricity  passing  through  it  is  termed 
by  Faraday  an  electrolyte;  the  elements  liberated  by  this  decomposi- 
tion he  terms  ions,  distinguishing  those  liberated  at  the  cathode  as 
cations,  which  in  sulphate  of  copper  would  be  the  metal,  and  those 
liberated  at  the  anode  as  anions,  which  would  be  the  acid  portion 
of  the  sulphate  of  copper. 

The  late  Professor  Daniell,  disapproving  of  the  terms  cathode 
and  anode,  substitued  platinode  for  the  negative,  and  zincode  for  the 
positive,  pole.  We  think  these  terms  are  better  adapted  for  electro- 
metallurgy than  cathode  and  anode,  which  have  no  direct  refer- 
ence to  ordinary  conditions;  while  zincode  distinctly  expresses 
the  substance  dissolved,  and  platinode  the  element  not  acted  upon. 

Professor  Graham  adopts  the  terms  zincous  and  chlorous  poles,  as 
synonymous  with  zincode  and  platinode,  or  positive  and  negative. 

Although  the  terms  positive,  negative,  and  pole,  may  not  be  the 


510  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

best,  still,  under  all  tlie  conditions  of  electro -metallurgy,  we  deem 
them  as  appropriate  as  any  of  the  proposed  substitutes,  some  of 
which  are  based  on  supposed  conditions  which  have  not  been 
proved,  and  may  be  found  incorrect. 

When  we  shall  have  occasion  to  use  the  two  terms  pole  and  eke- 
trode,  these  will  be  used  synonymously:  positive  and  negative  elec- 
trode are  synonymous  with  positive  and  negative  pole. 

Electrolyte  will  be  applied  to  a  solution  when  undergoing  decom- 
position by  the  electric  current  passing  through  it. 

The  positive  electrode,  or  pole,  is  that  metal  in  the  electrolyte 
which  is  being  dissolved,  or,  if  not  capable  of  being  dissolved,  at 
which  the  acid  or  solvent  of  the  electrolyte  is  being  liberated,  as 
when  sulphate  of  copper  forms  the  electrolyte,  the  sulphuric  acid 
is  liberated.  The  negative  electrode,  or  pole,  is  that  metal  or  sub- 
stance in  the  electrolyte  upon  which  the  metal  is  being  deposited 
by  the  influence  of  the  electric  current,  such  as  a  medal  upon  which 
copper  is  being  deposited  in  an  electrotype  process. 

BATTERIES. 

SINGLE  PAIR  OF  PLATES. — If  a  piece  of  ordinary  metallic  zinc 
be  put  into  dilute  sulphuric  acid,  it  is  speedily  acted  upon  by  the 
acid,  and  hydrogen  gas  is  at  the  same  time  evolved  from  its  sur- 
face, having  a  disagreable  smell  arising  from  impurities  contained 
in  the  zinc  or  acid.  If  the  zinc  be  taken  out,  and  a  little  mercury 
be  rubbed  over  its  surface,  an  amalgamation  takes  place  between 
the  two  metals:  the  plate  'becomes  of  a  beautiful  bright  silver 
appearance.  If  the  zinc  thus  amalgamated  be  again  put  into  the 
dilute  acid,  there  is  no  action,  for  the  mercury  retains  the  zinc  with 
sufficient  force  to  protect  it  from  the  acid.  If  a  piece  of  copper  be 
immersed  along  with  the  zinc,  and  the  two  metals  be  made  to  touch, 
each  other,  a  particular  influence  is  induced  among  the  three  ele- 
ments, zinc,  copper,  and  acid ;  the  acid  again  acts  upon  the  zinc  as 
if  no  mercury  was  upon  it,  but  the  hydrogen  is  now  seen  to  escape 
from  the  surface  of  the  coppery  this  action  will  go  on  as  long  as 
the  two  metals  are  kept  in  contact.  Or  if,  instead  of  causing  the 
two  metals  to  touch,  a  wire  be  attached  to  each,  and  their  opposite 
ends  are  placed  in  a  little  dilute  acid  in  another  vessel,  the  same 
action  will  take  place  between  the  zinc  and  copper  as  when  they 
were  in  contact ;  but  in  this  instance,  the  ends  of  the  two  wires 
which  dip  into  the  vessel  containing  acid  will  undergo  a  change : 
the  one  attached  to  the  zinc  will  give  off  a  quantity  of  hydrogen 
gas,  while  the  one  attached  to  the  copper,  supposing  it  to  "be  also 
copper,  will  rapidly  dissolve. 

Figure  542.  Represents  the  zinc  and  copper,  placed  in  dilute 
sulphuric  acid,  brought  into  contact ;  in  this  experiment,  gas  will 
be  seen  escaping  from  the  copper. 

Figure  543.  Zinc  and  copper,  placed  in  dilute  acid,  and  wires 
attached,  which,  when  connected,  will  exhibit  the  same  effects  as 
in  the  first  case. 


DESCRIPTION  OF   GALVANIC   BATTERIES. 


511 


Figure  544.  Shows  the  wires  connected  by  means  of  a  liquid, 
such  as  acid  and  water,  sulphate  of  copper,  etc. 


Figs.  542 


544. 


The  copper  and  zinc,  c  and  z,  with  the  acid  in  the  first  vessel, 
Figure  544,  constitute  a  battery  of  one  pair.  The  wine  glass  e,  wi 
acid,  in  which  the  wires  are  placed,  is  termed  the  decomposition 
cell. 

BEST  KIND  OF  ZINC. — The  zinc  used  for  the  battery  should  be 
milled  or  rolled  zinc,  not  thinner  than  £th  of  an  inch,  otherwise  the 
waste  will  be  very  great ;  for  amalgamated  zinc,  when  it  becomes 
thin,  is  so  tender  and  brittle,  that  the  utmost  care  cannot  preserve 
it  whole.  The  best  thickness  for  the  zincs,  when  their  size  is 
upwards  of  four  inches  square,  is  £th  of  an  inch ;  but  if  under 
this  size,  £th  to  T3gth  of  an  inch  is  the  proper  thickness.  Cast 
plates  of  zinc  should  not  be  used,  as -they  are  negative  to  rolled 
zinc,  and  give  less  electrical  power :  they  are  so  porous  that  no 
amalgamation  will  protect  them  from  the  action  of  the  acid — pro- 
ducing "  local  action,"  as  it  is  termed,  which  is  not  only  a  waste  of 
zinc  and  acid,  but  prevents,  to  a  great  extent,  the  production  of  the 
quantity  of  electrical  force  which  the  surface  of  the  zinc  in  use  is 
calculated  to  give.  9 

AMALGAMATION  OF  THE  ZINC  PLATES. — The  amalgamation  of 
zinc  is  a  process  exceedingly  simple ;  nevertheless,  if  care  be  not 
taken,  a  very  great  loss  in  mercury  and  zinc  is  soon  effected. 
A  stoneware  pan  is  best  to  use,  and  should  be  sufficiently  capa- 
cious to  allow  the  zinc  plate  to  lie  flat  within  it :  a  mixture  of 
eight  parts  water,  and  one  part  sulphuric  acid,  should  be  put  into 
the  pan,  sufficient  in  quantity  to  cover  the  zinc  plate,  whicn  should 
lie  in  it  till  the  surface  is  perfectly  bright.  The  pan  is  now  raised 
on  the  one  side,  and  a  little  mercury  put  into  the  lower  part,  care 
being  taken  that  the  zinc  does  not  touch  the  mercury,  to  prevent 
which  is  the  object  of  raising  the  pan  on  one  side.  A  little  coarse 
tow,  tied  to  the  end  of  a  piece  of  wood,  is  dipped  into  the  mercury, 
which  lifts  small  portions  of  the  metal  mechanically,  which  is  then 
rubbed  with  considerable  pressure  upon  both  sides  of  the  zinc 
plate,  over  which  the  mercury  flows  easily :  the  plate  is  then 
washed,  by  dipping  it  into  clean  water,  and  is  next  made  to  stand 
upon  its  edge  in  another  pan,  with  two  small  pieces  of  wood  under 


512  THE   PRACTICAL   METAL-WORKER  S  ASSISTANT. 

it,  so  as  to  allow  the  mercury  to  drain  from  it.  Instead  of  tow,  an 
old  scratch  brush  is  generally  used  in  plating  factories :  this  is  a 
brush  made  of  fine  brass  wire,  tied  upon  a  piece  of  wood ;  but  we 
prefer  tow,  when  carefully  employed,  as  the  brass  wire  amalga- 
mates with  the  mercury,  and  causes  a  loss  of  that  metal.  After 
the  zincs  have  drained  for  a  few  hours,  the  process  should  be 
repeated,  only  it  is  not  necessary  to  allow  the  metal  to  lie  in  the 
acid  in  the  second  process  previous  to  rubbing  in  the  mercury : 
after  draining  a  few  hours  the  second  time,  amalgamation  is  com- 
pleted. In  the  first  process  a  plate,  of  a  foot  square,  amalgamated 
on  both  sides,  will  retain  three  ounces  of  mercury ;  but  for  the 
second  process,  or  any  time  after,  the  same  size  of  plate  will  only 
retain  1£  ounces  of  mercury. 

Zinc  rapidly  absorbs  mercury,  which  permeates  the  whole  metal. 
If  the  mercury  was  in  quantity,  the  zinc  would  dissolve  in  it ; 
hence  the  propriety  of  rubbing  the  mercury  into  the  zinc,  only  in 
small  portion,  for  if  allowed  to  imbibe  as  much  as  it  is  capable  of 
doing,  it  would  not  only  be  a  loss  of  mercury,  but  the  plate  would 
become  exceedingly  brittle.  When  too  much  mercury  is  used,  a 
portion  of  it  will  filter  out  from  the  plate  by  standing,  but  it  carries 
with  it  some  zinc  dissolved,  which  tends  to  deteriorate  the  quality 
of  the  metal  for  the  battery. 

The  zinc  in  the  battery,  after  being  used,  should  never  be  allowed 
to  lie  in  the  acid  when  the  battery  is  not  in  use,  but  should  be  taken 
out,  and  the  surface  carefully  brushed  with  a  hard  hair  brush,  in 
water,  and  then  laid  by  in  a  safe  place.  The  matter  thus  brushed 
off;  being  an  amalgam  of  zinc,  is  to  be  carefully  collected,  and  kept 
in  dilute  sulphuric  acid,  or  in  the  waste  acid  from  the  batteries : 
most  of  the  zinc  in  this  amalgam  will  dissolve  out,  so  that  a  great 
portion  of  the  mercury  may  be  recovered,  or  by  placing  these 
brushings  in  a  coarse  cloth  bag,  and  subjecting  it  to  pressure  in  a 
screw-press,  most  of  the  mercury  may  by  this  means  be  recovered. 

ECONOMY  IN  AMALGAMATION.— If  the  battery  is  to  be  used  sel- 
dom, and  only  for  a  short  period  at  a  time,  another  method  of 
amalgamation  may  be  adopted.  The  zinc  plate,  after  lying  in  the 
dilute  acid  till  the  surface  is  bright,  may  be  rubbed  over  with  a 
solution  of  nitrate  of  mercury,  which  gives  a  very  thin  amalgama- 
tion ;  but  this  method  is  unsuitable  if  the  battery  is  to  be  in  use 
for  several  hours  together. 

When  a  battery  is  being  worked  daily,  it  will  be  advisable  to 
repeat  the  amalgamation  from  time  to  time,  otherwise  local  action 
will  begin,  and  the  working  power  of  the  battery  be  weakened, 
while  the  loss  in  zinc  will  be  increased. 

The  following  is  the  proportional  rate  which  we  have  found  on 
the  large  scale  under  the  most  favorable  circumstances.  A  new 
zinc  plate,  amalgamated  as  described,  working  continuously — 

24  hours,  zinc  lost  12 J  ounces — copper  deposited  12    ounces; 

48  hours,  zinc  lost  20|  ounces — copper  deposited  17    ounces ; 

60  hours,  zinc  lost  34    ounces — copper  deposited  24£  ounces. 


DESCRIPTION   OF   GALVANIC   BATTERIES.  513 

From  these  and  similar  data  we  found  that  the  most  economical 
way  of  using  zincs  is  the  following :  after  being  in  the  battery 
twenty-four  hours,  they  are  to  be  taken  out,  brushed,  and  laid 
aside ;  after  working  other  twenty -four  hours,  they  are  to  be  again 
brushed  and  immediately  re-amalgamated :  if  these  directions  are 
attended  to,  £  ounce  of  mercury  will  be  sufficient  for  one  foot 
square  of  zinc,  both  sides. 

The  advantages  of  proper  amalgamation  will  be  made  more  evi 
dent  in  the  sequel.  We  have  only  to  add  here,  in  consequence  of 
an  oft-expressed  fear  of  the  danger  of  working  with  quicksilver, 
that  no  apprehension  need  be  felt :  the  skin  does  not  absorb  it,  and 
there  being  no  heat  required  in  the  operation  that  could  convert 
the  mercury  into  vapor,  the  only  state  in  which  it  is  dangerous,  no 
salivation  can  take  place. 

DISTANCE  BETWEEN  THE  BATTERY  PLATES. — To  return  again 
to  the  battery-cell.  It  will  be  found  that  if  the  two  metals — the 
zinc  and  copper  in  acid,  Fig.  544 — be  put  very  close  to  each  other, 
the  action  will  be  much  more  rapid  than  when  they  are  far  apart. 
It  will  also  be  found  that,  allowing  the  zinc  and  copper  to  be  kept 
at  one  distance,  but  the  wires  in  the  decomposition-cell  to  be  put  at 
different  distances,  similar  results  will  take  place.  When  the  wires 
are  close  the  action  in  the  battery-cell  will  be  more  powerful  than 
when  the  two  wires  are  put  farther  apart :  these  properties  are  ap- 
plicable to  all  batteries  and  decomposition-cells .  of  every  kind. 
The  following  results  will  give  an  idea  of  .the  relations  of  these 
several  conditions : 

1st.  One  pair  of  copper  and  zinc  plates,  measuring  superficially 
6  square  inches,  were  immersed  in  a  solution  consisting  of  1  acid 
to  35  water :  plates  of  copper  of  equal  size  to  those  of  zinc  and 
copper  were  laid  in  the  decomposition-cell,  which  was  then  filled 
with  a  liquid  of  equal  strength  to  that  in  the  battery-cell ;  the 
plates  in  the  battery-cell  and  the  decomposition-cell  were  then 
placed  one  inch  apart :  in  four  hours 

The  zinc  in  the  battery-cell  lost  by  dissolving  10|  grains ; 
,    '      The  copper  dissolved  in  decomposition-cell  10  grains. 

2d.  The  battery-plates  were  put  12  inches  apart,  and  the  plates 
in  decomposition-cell  1  inch  apart :  in  four  hours 

There  were  dissolved  in  the  battery-cell,  zinc  7  grains ; 
In  decomposition-cell,  copper  6  grains. 

8d.  The  battery  plates  were  placed  1  inch  apart,  and  the  platea 
in  decomposition-cell  12  inches  apart :  in  four  hours 
The  zinc  in  battery-cell  lost  4  J  grains ; 
The  copper  in  decomposition-cell  lost  3J-  grains. 

These  results  show  the  importance  of  attending  to  the  condi- 
tions of  the  respective  agents,  and  also,  that  distance  in  the  decom- 
position-cell oft'ers  greater  resistance  than  distance  in  the  battery- 
cell. 

DIFFERENT  ELEMENTS  OF  BATTERIES. — Although  our  observa- 
tions have  been  made  on  zinc,  copper,  and  dilute  sulphuric  acid  in 

* 


514:  THE   PRACTICAL   METAL-WORKER'ri  ASSISTANT. 

the  battery -cell,  still  these  are  not  the  only  essential  elements  in  a 
battery,  as  almost  any  two  metals  with  a  liquid  similarly  arranged 
will  produce  an  electric  current ;  but  the  current  will  vary  accord- 
ing to  the  nature  of  the  metals  employed,  and  the  effects  produced 
upon  them  by  the  solution  in  which  they  are  placed.  If  the  ex- 
citing solution  has  the  power  of  acting  upon  both  metals,  as  when 
zinc  and  copper  are  immersed  in  dilute  nitric  acid,  the  current  of 
electricity  produced  by  the  action  of  the  acid  upon  the  zinc  will 
be  neutralized  to  an  extent  corresponding  to  the  relative  action  of 
the  acid  upon  the  copper.  To  have  any  effective  electrical  power, 
it  is  necessary  that  one  of  the  metals  employed  be  capable  of  com- 
bining easily  with  one  of  the  elements  of  the  solution  in  which 
they  are  placed,  and  forming  a  soluble  salt,  while  the  other  does 
not ;  and  the  power  obtained  under  proper  circumstances  has  an 
intimate  relation  with  these  two  properties  in  contrast.  The  metal 
which  undergoes  solution  is  termed  the  positive  metal,  the  other 
the  negative  metal.  Metals  are  not  considered  to  possess  any  in- 
trinsic negative  or  positive  principle ;  their  relations  in  this  respect 
are  governed  solely  by  the  circumstances  in  which  they  may  be 
placed.  For  instance,  if  we  connect  a  piece  of  copper  and  a  piece 
of  iron,  and  immerse  them  in  acidulated  water,  the  iron  is  dissolved, 
and  is  positive  in  relation  to  the  copper  ;  but  if  the  same  metals 
are  immersed  in  a  solution  of  yellow  hydro-sulphuret  of  potassium, 
the  copper  is  dissolved,  and  is  positive  relatively  to  the  iron. 
Hence,  to  obtain  a  galvanic  battery,  the  conditions  are  simply  to 
provide  two  metals,  and  immerse  them  in  a  solution  capable  of 
acting  upon  the  one  and  not  upon  the  other.  The  first  table  shows 
the  order  in  which  the  common  metals  stand  to  each  other,  in  re- 
spect of  their  relative  negative  and  positive  properties,  when  im- 
mersed in  water  acidulated  with  sulphuric  acid.  The  second  table 
is  given  by  Gmelin  as  the  relations  of  the  metals,  in  water  and  sea 
water,  the  most  intensely  negative  metal  standing  highest,  and  the 
metal  which  acts  most  positively  standing  lowest : 

Platinum  Platinum 

Gold  Gold 

Antimony  Silver 

Silver  Copper 

Nickle  Bismuth 

Bismuth  Antimony 

Copper  Iron 

Lead      \  Tin 

Iron  Lead 

Tin  Cadmium 

Cadmium  Zinc 
Zinc 

According  to  this  arrangement,  each   metal   is  positive  with 
respect  to  all  that  stand  before  it,  and  the  electrical  conditions  of 


DESCRIPTION  OF   GALVANIC  BATTERIES.  515 

any  pair  become  the  more  contrasted  the  further  apart  they  stand 
in  the  scale.  Thus,  a  battery  composed  of  zinc  and  platinum  is 
much  more  powerful  than  one  composed  of  zinc  and  copper;  and 
again,  copper  and  iron  make  a  very  weak  battery. 

A  battery  may  also  be  formed  by  having  one  metal  and  two 
kinds  of  solutions,  separated  by  a  porous  diaphragm.  For  example, 
we  may  have  strong  nitric  acid  in  one  division,  and  dilute  sulphuric 
or  muriatic  acid  in  the  other ;  and  by  putting  into  each  a  piece  of 
clean  iron,  a  powerful  current  is  obtained.  These  and  several 
other  arrangements  of  solutions  and  metals,  are  expensive  and 
troublesome  to  keep  in  order,  and  are  therefore  never  used  for 
practical  purposes  in  the  art  of  electro-metallurgy. 

PROPERTIES  OF  METALS  FIT  FOR  BATTERIES.— In  looking  to  the 
above  table,  it  may  be  asked,  "  Since  lead  stands  next  to  copper, 
and  is  so  much  cheaper,  why  should  it  not  be  used  instead?"  The 
reason  is,  that  there  are  other  properties  which  a  metal,  especially 
that  used  as  the  negative  element,  ought  to  possess  to  fit  it  for  use 
in  a  voltaic  arrangement ;  such  as  the  power  of  freely  conducting 
an  electric  current,  of  keeping  a  bright  surface,  and  not  becoming 
oxidized ;  none  of  which  properties  belong  to  lead.  Could  that 
metal  be  kept  from  oxidizing,  a  very  powerful  current  of  electricity 
might  be  obtained  by  using  it  with  zinc ;  but  its  surface  soon  gets 
coated  with  an  oxide  possessing  none  of  the  properties  of  the  metal, 
and  hence  the  arrangement  becomes  zinc  and  oxide  of  lead,  which 
produces  but  a  weak  current  of  electricity.  These  remarks  refer 
to  any  metal  that  is  subject  to  oxidization — an  incident  which  is 
often  a  source  of  annoyance  to  the  electrotypist  when  using  copper 
plates. 

Lead  slightly  amalgamated,  and  used  as  the  negative  metal  with 
zinc,  produces  a  very  constant  current  for  a  time. 

Lead  is  also  a  very  bad  conductor  of  the  electric  current,  which 
renders  it  unsuitable  for  an  element  in  the  battery,  the  negative 
metal  being  considered  as  only  acting  the  part  of  a  conductor:  this 
property  materially  affects  the  available  power  of  an  arrangement. 

The  following  table  shows  the  relative  Conducting  power  of  the 
respective  metals : 

Silver  .        .        .  120 

Copper  .        .        .  120 

Gold  ...  80 

Zinc  ...  40 

Platinum          .        .  24 

Iron  ...  24 

Tin  ...  20 

Lead  ...  12 

We  have  just  stated  that  a  battery  composed  of  zinc  and  pla- 
tinum will  be  more  powerful  than  one  composed  of  zinc  and  cop- 
per, so  far  as  regards  their  negative  and  positive  tendencies ;  but 


516  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

so  much  does  the  conducting  power  of  the  negative  metal  affect 
the  practical  usefulness  of  a  battery,  that  notwithstanding  the  fact 
that  platinum  is  much  more  negative  than  copper,  there  is  so  much 
of  the  effective  electricity  expended  in  overcoming  the  resistance 
which  the  inferior  conductibility  of  the  platinum  offers  to  the  pro- 
gress of  the  current  that  a  battery  of  zinc  and  copper  proves  to  be 
a  more  effective  and  useful  battery  for  electro-metallurgy  than  one 
made  of  zinc  and  platinum.  Hence  also  the  reason  that  iron  and 
copper,  or  iron  and  any  other  metal,  make  but  an  indifferent  battery 
— iron  being  a  bad  conductor ;  while  lead,  which  will  be  seen  in 
the  table,  stands  lowest  in  this  property,  is  therefore  unfit  for  bat- 
teries. 

In  fitting  up  a  voltaic  arrangement  with  a  negative  metal  that  is 
not  a  good  conductor,  such  as  platinum,  the  closer  it  is  placed  to 
the  exciting  liquid,  in  connection  with  another  metal  that  is  a  good 
conductor,  the  better ;  because  the  current  obtained  will  be  the 
more  effectual. 

The  following  experiments  will  illustrate  these  remarks  with  a 
few  of  the  common  metals  used  as  negative  electrodes.  There 
were,  in  each  battery,  six  square  inches  of  each  metal  exposed  to  the 
action  of  the  acid,  which  was  sulphuric  acid  diluted  with  25  parts 
of  water.  The  poles  were  of  the  same  size,  of  copper,  placed  in 
sulphate  of  copper;  and  the  quantity  of  copper  deposited  was 
taken  as  the  data,  each  trial  being  of  a  different  length  of  time : 

FIRST,   IN  ACTION  HALF  AN  HOUR. 

BATTERY.  DEPOSITED. 

Tin  and  zinc     ....  1'7  grains. 

Copper  and  zinc        .    '    V —  '    .  1*8       " 
Platinum  and  zinc    .         .  *5       " 

Platinized  silver  and  zinc          .  2'0       " 

SECOND,  IN  ACTION  TWO  AND  A-HALF  HOURS. 

Tin  and  zinc     ....  5'9  grains. 

Copper  and  zinc        .         .         .  8'8       " 

Platinum  and  zinc    .         ,         .  4'5       " 

Platinized  silver  and  zinc          .  97       " 

THIRD,  IN  ACTION  SIXTEEN  HOURS. 

Tin  and  zinc     ....  64*5  grains. 
Copper  and  zinc       .         .         .  50*5       " 
Platinum  and  zinc    .         .         .  43'0       " 
Platinized  silver  and  zinc        .  67'3       " 

From  these  few  experiments  it  appears  that  tin  and  zinc,  when 
used  for  a  long  time,  constitute  a  very  effective  battery.  It  is 
very  constant  in  its  action,  and  thus  suited  for  time.  It  stands 
next  to  platinized  silver.  The  whole,  in  nineteen  hours,  gave 
respectively — 


DESCRIPTION  OF   GALVANIC  BATTERIES. 


517 


Platinized  silver 

Tin  .  .,.  ..,. 
Copper  .  .  . 
Platinum 


79-    grains. 
72-1       " 
61-1 

48-0      " 


BABINGTON'S  BATTERY. — If  we  look  back  to  tk£  description 
given  of  the  voltaic  pile  (page  489),  and  the  improvement  made  upon 
it  by  Cruikshanks,  we  perceive  the  relation  they  bear  to  the  pieces 
of  copper  and  zinc  mentioned  in  page  510  ;  but  the  relation  is  more 
apparent  in  Babington's  improvement  upon  Cruikshank's  battery. 
When  working  with  this  battery,  it  was  found  that  the  energy  of 


545 


546. 


Fig.   547. 


the  battery  did  not  depend,  as  was  supposed,  upon  the  extent  of 
surface  of  the  zinc  and  copper  which  were  in  contact,  but  upon 
the  extent  of  surface  of  these  metals  in  contact  with  the  liquid 
with  which  the  battery  was  excited  ;  and  that  it  was  sufficient  if 
the  zinc  and  copper  touched  each  other  in  a  single  point ; — pro- 
vided that  the  plates  were  plunged  into  the  liquid,  and  that  the 
copper  plate  should  be  exactly  opposite  to  a  zinc  plate  in  the  same 
cell,  a  space  between  them.  Hence,  instead  of  soldering  the  zinc 
and  copper  together,  as  Mr. 
Cruikshanks  did,  it  was 
enough  to  effect  a  communi- 
cation by  turning  over  a  por- 
tion of  the  copper  plate  at 
the  top,  and  soldering  it  to 
the  upper  extremity  of  the 
zinc.  Thus — c,  the  copper, 
is  bent  over  to  touch  and  be 
soldered  to  the  zinc  plate  z. 
For  this  arrangement,  the 
wooden  trough  was  diyided, 
by  plates  of  glass  or*  var- 
nished wood,  into  as  many 
cells  as  there  were  pairs  of 
zinc  and  copper.  The  cells 
being  filled  with  the  acid,  or 
exciting  solution,  the  metals 
were  then  placed  into  them  in  such  a  manner  that  each  pair  of 


518 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 


zinc  and  copper  plates  had  a  partition  between.  By  this  arrange- 
ment the  zinc  of  one  pair  faced  the  copper  of  the  next  pair  in  the 
cell,  as  shown  in  Figures  546  and  547.  The  former  represents  the 
plates  immersed  in  the  solution  ;  the  latter,  the  plates  suspended  on 
a  rack  over  the  solution.  This  arrangement  was  termed  Babing- 
ton's  Battery. 

WOLLASTON'S  BATTERY. — Although  we  have  spoken  of  the 
great  value  of  amalgamated  zinc  for  batteries,  still  at  the  period 
when  the  arrangement  just  described  was  introduced,  amalgama- 
tion was  not  known ;  and  the  zinc  plates  were,  therefore,  always 
liable  to  be  destroyed  by  the  acid.  It  was,  consequently,  of  im- 
portance that  no  zinc  should  be  exposed  to  the  action  of  the  acid 
that  was  not  calculated  to  give  electricity,  as  the  energy  of  each 
pair  of  plates  depends  upon  the  extent  of  surface  of  the  two  metals 
exactly  opposite  to  each  other.  It  will  be  evident  that  in  Babington's 
arrangement  only  one  side  of  the  zinc  was  effective  in  giving  elec- 
tricity, while  both  sides  were  exposed  to  the  action  of  the  acid.  To 

obviate    this    defect,    Dr. 

Fis-  548.  Wollaston  caused  the  cop- 

per plate  to  surround  the 
zinc,  by  which  the  whole 
surface  of  the  zinc  exposed 
to  the  acid  was  made  effec- 
tive in  producing  electric- 
ity, and  thereby  doubling 
its  quantity  without  further  cost.  The  accompanying  figure  (Fig. 
548)  shows  the  manner  in  which  this  battery  was  originally  con- 
structed. 

This  improvement,  if  we  except  several  modifications  of  con- 
struction for  the  facility  of  taking  the  plates  asunder  for  cleaning, 
etc.,  did  all  for  this  kind  of  battery  that  could  be  done. 

MODIFICATION  OF  WOLLASTON'S  BATTERY  NOW  IN  USE. — Wol- 
laston's  battery  is  still  generally  used  in  large  factories  for  deposit- 
ing metals ;  and  it  is  found  by  experience  to  be  the  most  convenient 
and  economical  of  all  the  batteries  yet  contrived.  The  modifica- 
tion we  have  found  to  be  very  suitable,  and  practically  useful,  may 
-be  thus  described.  In  the  arrangement  represented  above,  when 
amalgamated  zincs  are  used,  small  quantities  of  amalgam  fall  from 
the  zinc  plates  upon  the  copper,  which  not  only  occasion  local 
action,  but  the  mercury  amalgamates  with  the  copper,  spreads  over 
it,  and  to  a  great  extent  lessens  its  efficiency ;  and  as  the  copper 
must  be  red  hot  to  expel  the  mercury, 
much  loss  of  copper  as  well  as  mercury 
is  the  result.  To  obviate  this  defect,  the 
copper  is  connected  above  the  zinc  and 
left  open  at  bottom;  as,  for  example,  a 
thin  sheet  of  copper,  of  dimensions  accord 
ing  with  the  size  of  the  cells  in  the  battery,  is  cut  thus :  This  cop- 
per is  bent  in  the  middle  at  I,  the  ends  a  a  dip  into  the  cells,  while 


Fig.  540. 


DESCRIPTION   OF   GALVANIC   BATTERIES. 


519 


c  is  bent  over  to  connect  with  the  zinc  plate  of  the  neighboring 
cell,  thus : 

Figs.  550  551. 


The  zinc  plates  are  placed  between  the  bent  copper  a  a.  The  fol- 
lowing diagram  of  a  battery  of  several  pairs  of  plates  will  illustrate 
these  observations : 


Fig.  552. 


z  z  z  z.  The  zinc  plates. 

c  c  c  c,  Copper  plates. 

PPP,  Partitions  of  trough, 
which  are  generally  made 
of  thin  wood. 

ww, Wires  from  battery. 


NJDI 


I — Jh==v 


The  zinc  and  copper  are  connected  together  by  a  binding  screw. 
To  construct  this  battery  the  zinc  plates  are  put  in  first,  being 
made  to  slide  in  grooves,  cut  in  the  sides  of  the  trough,  the  plates 
standing  in  the  centre  of  their  respective  cells:'  the  copperplates 
are  put  in,  and  the  copper  bands  marked  c  are  made  fast  To  the 
zincs  by  binding  screws,  care  being  taken  that  the  parts  where 
they  are  connected  are  clean  and  bright,  and  that  the  copper  and 
zinc  touch  nowhere  else.  A  battery  of  nine  pairs  of  plates  can 
be  fitted  up  and  made  ready  for  action  in  ten  minutes. 

In  fitting  up  batterieS  of  this  sort,  we  are  aware  that  sometimes 
great  care  is  taken  that  the  partitions  in  the  trough  be  perfectly 
water-tight,  and  also  formed  of  some  non-conducting  material,  such 
as  glass,  or  of  wood,  either  pitched  or  saturated  with  some  non-con- 
ducting substance ;  but  we  have  found  in  practice  that  these  pre- 
cautions are  not  required,  the  principal  thing  to  attend  to  being, 
that  the  metals  should  not  be  allowed  to  touch,  except  in  their 
proper  connections. 

DEFECTS  OF  COMMON  ACID  BATTERIES. — Although  we  have 
spoken  thus  favorably  of  the  principles  upon  which  Wollaston's 
battery  is  constructed,  still  as  a  philosophical  instrument  it  is  far 
from  being  perfect:  hence  the  many  modifications  of  it  which  have 
been  recommended.  Indeed,  electro-chemists,  since  the  time  of 
Yolta,  have  been  endeavoring  to  invent  an  instrument  free  from 
the  defects  which  attach  to  Wollaston's — one  capable  of  giving,  at 


520  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

the  same  time,  a  constant  and  powerful  current,  abundant  in  quan- 
tity, and  of  great  intensity.  The  success  and  results  of  these  en- 
deavors are  so  closely  connected  with  the  art  of  electro-metallurgy, 
and  the  knowledge  of  them  is  so  essential  to  a'  successful  prosecu- 
tion of  the  art,  that  we  must  not  be  sparing  in  our  descriptive  details. 

In  operating  with  a  Wollaston's  battery,  or  any  other  arrange- 
ment composed  of  similar  elements,  such  as  zinc,  sulphuric  or 
muriatic  acid,  and  copper,  silver  or  platinum,  it  will  be  found  that  the 
current  of  electricity  obtained  diminishes  in  quantity  and  strength 
in  proportion  to  the  time  of  action.  This  is  the  result  of  various 
causes : 

1st.  The  hydrogen  which  is  evolved  at  the  surface  of  the  nega- 
tive metal  in  the  battery,  which  we  shall  say  is  copper,  adheres 
with  considerable  force  to  the  surface  of  the  metal,  and  consequently 
obstructs  its  superficial  influence,  so  that  the  quantity  of  electricity 
which  the  surface  of  the  two  metals  is  calculated  to  give  is  much 
lessened. 

2d.  After  the  battery  is  in  action  a  short  time,  a  portion  of  the 
sulphate  or  chloride  of  zinc,  formed  in  the  battery  by  the  solution 
of  the  zinc,  becomes  reduced  upon  the  surface  of  the  copper.  This 
reduction  is  supposed  to  be  owing  to  the  electrolyzation  of  the  zinc 
solution  by  the  passage  of  electricity,  but  it  is,  more  probably, 
caused  by  a  galvanic  action  upon  the  copper  plate  and  the  solution 
in  the  battery.  It  generally  begins  at  the  lower  edge  of  the  copper 
plate,  and  spreads  upwards.  This  weakens  the  electric  current, 
both  by  inducing  a  galvanic  action  between  the  zinc  and  the  cop- 
per, upon  which  it  is  deposited,  and  by  its  tendency  to  send  a  cur- 
rent of  electricity  in  an  opposite  direction  to  the  main  current,  thereby 
neutralizing  to  a  great  extent  the  original  power  of  the  circle. 

3d,  When  copper  is  used  it  becomes  gradually  covered  over  with 
a  thin,  black,  slimy  coating  of  oxide  and  other  impurities,  which 
materially  affects  the  regularity  and  strength  of  the  current :  this 
is  a  source  of  considerable  annoyance  in  working,  and  necessitates 
a  regular  cleaning  of  the  coppers,  which  should  be  done  immedi- 
ately on  being  taken  out  of  the  battery,  by  brushing  with,  a  hard 
hair  brush  in  water;  but  when  the  battery  has  been  long  in  action, 
this  mode  of  cleaning  is  insufficient:  the  plates  will  then  require 
to  be  rubbed  over  with  a  little  dilute  nitric  acid,  and  then  washed. 
If  the  black  coating  be  allowed  to  dry  upon  the  coppers,  they  must 
then  be  dipped  into  strong  nitric  acid  till  their  surfaces  are  acted 
upon ;  or  they  may  be  moistened  with  a  little  urine,  then  brought 
to  a  dull  red  in  the  fire,  and  immediately  plunged  into  water;  but 
in  both  cases  there  is  a  loss  of  copper.  A  small  quantity  of  the 
black  matter,  upon  being  tested,  gave  oxide  of  copper,  with  a  trace 
of  iron,  antimony,  and  lead,  which  are  the  general  impurities  of 
sheet  copper. 

Max,  Duke  of  Leuchtenberg,*  has  giving  the  following  results 

i __ 

*  Progress  of  General  Science,  vol.  ii. 


DESCRIPTION  OF  GALVANIC  BATTERIES.  521 

of  an  analysis  of  the  black  matter  found  upon  the  copper  plate 
forming  the  positive  electrode  in  a  copper  solution. 

Sand    .     '  ,'        ;  :-'••.         .         .  1'90 

Antimony  .     TI  ;»>..,*•.         .         .  9'22 

Tin       .  .        .    .     .         .         .  33-50 

Arsenic  .        .         .    *  :v>   *  .  7'40 

Platinum  .        •.      '  .  -  i*v<  •  '  .  0*44 

Gold     .  .    •**'.»&  .     --.-.v  .  0-98 

Silver  .  .    '    .        .  &$$$!  .  4-45 

Lead Olo 

Copper 9'24 

Iron 0-30 

Nickle  .....  2-26 

Cobalt 0-86 

Vanadium 0'64 

Sulphur  .         .        .        ...  2-46 . 

Selenium  .     ~  ..  .•'-•#. <*'••' -;  v^   •*.'  1*27 

Oxygen 24-82 


99-98  M 

An  analysis  of  this  sort  invests  the  subject  with  great  interest. 
We  wish  there  had  also  been  given  an  anai}rsis  of  the  copper  that 
was  used  as  the  electrode,  and  the  quantity  of  black  matter  obtained, 
and  the  quantity  of  copper  dissolved  to  yield  that  product :  for  the 
analysis  indicates  an  amount  and  diversity  of  impurities  in  copper 
that  has  never  hitherto  been  thought  of.  Both  the  number  and 
the  proportions  are  startling.  However,  it  is  a  known  fact,  that 
the  more  impure  the  copper  is  that  is  used  for  a  pole,  the  black 
matter  is  not  only  more  easily,  but  more  abundantly  produced. 

Another  source  of  weakness  to  the  electric  current,  and  which 
affects  more  or  less  all  batteries  of  whatever  construction,  arises 
from  the  action  of  the  acid  upon  the  zinc.  The  more  freely  this 
action  is  allowed  to  proceed  the  more  constant  and  powerful  is  the 
battery.  The  acid  in  combining  with  the  zinc  forms  a  salt,  which, 
if  it  adhered  to  the  surface  of  the  plate,  would  soon  stop  further 
action ;  but  this  salt  being  soluble  in  water,  is  dissolved  from  the 
surface- of  the  plate  as  soon  as  formed,  allowing  a  new  surface  to 
be  exposed.  But  water  can  only  dissolve  a  certain  quantity  of 
the  salt,  and  its  power  of  dissolving  decreases  as  it  approaches  to 
the  limit  of  saturation :  hence  there  is  a  constant  tendency  to  a 
decrease  of  power  in  the  battery,  and  if  means  be  not  taken  to  with- 
draw the  salt  of  zinc  formed,  the  battery  will  continue  to  decrease 
in  power,  till  at  length  it  ceases  to  act.  But  long  before  the  battery 
ceases  to  act,  the  presence  of  sulphate  of  zinc  manifests  itself  in 
several  ways,  neutralizing  the  efficacy  of  the  battery.  The  zinc 
salt,  as  it  dissolves  from  the  plate,  being  heavier  than  the  acid  solu- 
tion, falls  to  the  bottom ;  hence  in  a  very  short  time  the  solution  is 


522  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

formed  of  strata  of  different  densities,  and  this  induces  a  galvanic 
action  between  the  lower  and  upper  portions  of  the  plates,  both  cop- 
per and  zinc,  and  accounts  for  the  deposition  of  zinc  on  the  bottom 
part  of  the  plates,  as  above  referred  to.  This  local  galvanic  action 
between  the  bottom  and  top  parts  of  the  zinc  plate  is  sometimes  so 
great  when  the  battery  has  been  long  in  action,  as  to  double  the 
thickness  of  the  zinc  plate  at  bottom,  while  the  part  near  the  surface 
of  the  solution  is  nearly  penetrated  by  the  acid ;  and  when  a  battery 
is  formed  of  a  number  of  pairs,  the  terminal  zincs  are  those  most 
affected,  the  one  forming  the  negative  terminal  or  pole  more  so 
than  the  other.  We  have  found  a  deposition  of  6|  ounces  of  zinc 
upon  the  two  lower  inches  of  a  plate  terminal,  which  measured,  in 
the  solution,  six  inches  by  five,  the  battery  having  been  in  opera- 
tion but  eighteen  hours.  When  this  occurs,  the  quantity  of  elec- 
tricity circulating  through  the  battery  is  very  small.  Although 
this  evil  may  not  proceed  to  the  extent  of  having  quantities  of 
zinc  deposited  upon  the  bottom  part  of  the  plates,  still  the  tendency 
to  deposition  which  every  one  who  employs  a  battery  must  have 
observed,  as  also  the  more  rapid  action  of  the  acid  on  the  upper 
parts  of  the  plates,  shows  that  the  action  of  the  acid  over  the  sur- 
face  of  the  plate  is  very  irregular,  and  consequently  the  quantity 
of  electricity  must  be  irregular  in  the  same  degree,  often  produc- 
ing in  the  battery  an  intermittent  action. 

Various  means  have  been  devised  for  removing  the  sulphate  of 
zinc,  and  adding  corresponding  quantities  of  new  acid  water ;  the 
most  simple  and  effective  of  which,  according  to  our  experience, 
is  to  make  the  battery  trough  much  deeper  than  is  required  for 
the  plates,  which  may  be  supported  either  by  grooves  in  the  side 
of  the  trough,  cut  to  the  proper  depth,  or  by  a  fillet  of  wood,  or 
perforated  false  bottom ;  so  that  the  zinc  salt  when  formed  may 
fall  under  the  plates,  and  thus  a  much  longer  time  elapse  before 
its  presence  produces  any  decidedly  bad  effect. 

There  can  be  no  doubt,  we  think,  that  some  easy  means  will  yet 
be  devised  for  carrying  off  the  dense  solution  of  sulphate  of  zinc, 
before  it  rises  to  the  plates,  and  for  replacing  it  by  acid  water  from 
above,  thus  giving  to  the  battery  a  uniformity  and  steadiness  of 
action  it  does  not  at  present  possess.  There  have  been  many  in- 
genious contrivances  tried  for  this  purpose  by  the  amateur,  but 
we  have  seen  none  so  'simple  and  economical  for  manufacturing 
purposes,  as  that  referred  to. 

DANIELL'S  BATTERY.— A  few  years  ago,  some  of  the  disadvan- 
tages now  detailed  were  to  a  great  extent  overcome  by  a  very  in- 
genious arrangement  discovered  by  the  late  Professor  Daniell. 
The  discovery  consists  in  the  separation  of  the  zinc  from  the 
copper  by  a  porous  diaphragm,  such  as  bladder,  unglazed  porce- 
lain, etc.,  and  the  use  of  two  distinct  fluids.  The  portion  of  the  bat- 
tery containing  the  zinc  is  charged  with  dilute  acid  as  before,  but 
the  portion  containing  the  copper  is  filled  with  a  solution  of  sul- 
phate of  copper.  The  action  in  this  battery  is  similar  to  that 


DESCRIPTION   OF   GALVANIC  BATTERIES. 


523 


Fig.  553. 


described  in  the  ordinary  battery ;  the  zinc  is  dissolved  by  the 
acid,  but  the  hydrogen,  instead  of  being  evolved  at  the  copper 
plate,  combines  with  the  acid  of  the  sulphate  of  copper :  metallic 
copper  is  thu^  set  at  liberty  upon,  and  combines  with,  the  copper 

Elate  of  the  battery,  not  only  maintaining  but  improving  its  sur- 
ice,  during  the  evolution  of  a  constant  cur- 
rent of  electricity.  From  the  constancy  of  the 
current  maintained  the  battery  has  been  termed 
the  Constant  Battery.  The  construction  of  a 
single  pair  is  described  by  Professor  Daniell 
in  the  following  terms : 

"A  cell  of  this  battery  consists  of  a  cylin- 
der of  copper  3£  inches  in  diameter,  which 
experience  has  proved  to  afford  the  most  ad- 
vantages between  the  generating  and  conduct- 
ing surfaces,  but  which  may  vary  in  height 
according  to  the  power  which  it  is  wished  to  obtain.  A  mem- 
branous tube,  formed  of  the  gullet  of  an  ox,  is  hung  in  the  centre 
by  a  collar,  and  a  circular  copper  plate,  resting  upon  a  rim,  is 
placed  near  the  top  of  the  cylinder,  and  in  this  is  suspended,  by  a 
wooden  cross-bar,  a  cylindrical  rod  of  amalgamated  zinc,  half  an 
inch  in  diameter;  the  "cell  is  charged  with  eight  parts  of  water,  and 
one  of  oil  of  vitriol,  which  has  been  saturated  with  sulphate  of 
copper,  and  portions  of  the  solid  salt  are  placed  upon  the  upper 
copper  plate,  which  is  perforated  like  a  collander  for  the  purpose 
of  keeping  the  solution  always  in  a  state  of  saturation.  The  in- 
ternal tube  is  filled  with  the  same  acid  mixture  without  the  copper. 
A  tube  of  porous  •  earthenware  may  be  substituted  for  the  mem- 
brane with  great  convenience,  but  probably  with  some  little"  loss 
of  power.* 

A  number  of  such  cells  may  be  connected  very  readily,  by  attach- 
ing the  zinc  of  the  one  tg  the  copper  of 
the  other,  and  (as  shown  in  Fig.  554)  thus 
forming  an   intensity  arrangement   of 
great  power  and  constancy. 

This  arrangement  of  battery  is  emi- 
nently suited  to  all  kinds  of  electrical 
operations,  and  it  may  be  borne  in  mind 
that  it  was  by  operating  with  this  bat- 
tery the  idea  of  electro-metallurgy  first 
occurred.  In  tlfis  battery  we  see  that  the  evils  arising  from  the 
slow  liberation  of  the  hydrogen  from  the  surface  of  the  negative 
metal,  and  the  deposition  of  the  zinc  upon  the  copper,  and  also 
the  blackening  of  the  surface  of  the  copper,  are  all  surmounted. 
Nevertheless  it  is  not  used  to  any  extent  in  the  art  of  electro- 
metallurgy, it  being  much  less  economical  than  the  ordinary  bat- 
teries, from  the  quantity  of  copper  salt  necessary  to  keep  it  in  a  work- 


Fig.  554. 


*  Daniell's  Chemical  Philosophy,  2d  edition,  1843,  p.  504. 


524  THE    PRACTICAL    METAL-WORKER'S  ASSISTANT. 

ing  condition,  and  from  the  necessity  of  using  porous  diaphragms, 
which  speedily  wear  out.  If  the  diaphragm  is  made  of  animal 
membrane,  the  acid  very  soon  destroys  it ;  and  although  unglazed 
porcelain  lasts  a  little  longer,  the  acid  acts  upon  thq  alumina,  so 
that  after  a  few  days'  working  the  diaphragm  becomes  too  porous  ; 
and  if  the  zinc  plate  touches  the  porous  vessel,  a  circumstance  very 
difficult  to  avoid,  there  is  very  soon  formed  in  and  upon  the  porous 
surface  a  deposit  of  copper  which  speedily  renders  the  cell  useless, 
besides  producing  a  loss  of  copper.  The  saturation  of  the  zinc 
solution,  already  spoken  of,  not  unfrequently  produces  the  same 
effects — the  saturated  portion  of  the  bottom  becomes  reduced  by 
the  local  action,  and  thus  often  a  minute  point  of  metallic  zinc 
touches  the  cell,  and  forms  a  nucleus  for  a  deposit  of  copper  upon 
the  porous  cell,  which  spreads  over  the  surface  very  rapidly. 
There  are  always  pieces  of  amalgamated  zinc,  like  fine  scales,  fall- 
ing to  the  bottom  of  the  cell,  which  also  form  nuclei  for  the  deposi- 
tion of  qbpper  upon  the  porous  cell. 

After  the  cells  have  been  some  time  in  use,  if  they  are  laid  aside 
and  allowed  to  dry,  they  are  very  liable  to  break.  Care  should  ibe 
taken  to  keep  them  in  clean  water  till  the  salts  within  the  pores 
are  dissolved  out ;  but  if  this  precaution  is  taken  they  may  be 
preserved  for  a  long  time  if  only  used  occasionally. 

The  remarks  upon  the  economy  of  the  arrangement  just  de- 
scribed have  reference  to  its  use  as  an  instrument,  or  separate  bat- 
tery, for  the  deposition  of  a  metal  in  a  separate  cell  (decomposi- 
tion cell) ;  but  not  to  the  arrangement  known  in  electro-metallurgy 
as  the  single  cell  process,  which  is  simply  a  modification  of  one 
pair  of  Daniell's  arrangement;  a  description  of  which,  with  its 
comparative  economy,  will  be  given  in  another  part  of  this  treatise. 
Professor  Daniell  says  that  any  depth  of  cell  may  be  used  ac- 
cording to  the  power  required,  but  this  cannot  be  done  with  equal 
advantage,  for  a  large  surface  of  zinc  in  a  cell  is  not  the  most 
economical,  when  a  great  quantity  of  electricity  is  required. 

GROVE'S    BATTERY. — Another   battery,  constructed  upon  the 
same  principle  as  Daniell's,  but  differing  in  the  arrangement  of  the 
metals,  and  the  substances  used  to  excite  them,  was  invented  by 
Mr.  Grove,  and  is  known  as   Grove's  Battery.     Tn  this  arrange- 
ment, platinum  is  used  instead  of  copper,  and  strong  nitric  acid  in- 
stead of  the  sulphate  of  copper  of  Daniell's  bat- 
Fig.  555.  tery.     Qne  pair  may  ke  fitted  up  conveniently 
J       in  a  tumbler  or  jelly-pot.     A  c^inder  of  zinc  is 
placed  inside  the  tumbler ;  within  this  cylinder  is 
placed  a  porous  vessel,  in  which  is  a  slip  of  pla- 
tinum either  in  sheet  or  foil ;  the  porous  vessel 
is  filled  with  strong  nitric  acid,  and  the  tumbler 
with  dilute   sulphuric  acid:    a  wire  is  next  at- 
tached to  each  metal,  and  the  battery  is  complete. 
When  a  series  of  pairs  is  to  be  used,  the  form  we  have  found  most 
convenient  is  to  arrange  the  metals  in  the  same  manner  as  we  have 


DESCRIPTION"   OF   GALVANIC   BATTERIES. 


525 


described  for  "Wollaston's  trough  (page  518).  The  zinc  is  formed 
in  the  same  shape  as  shown  by  Fig.  555.  The  zinc  is  placed  in  the 
cell  of  the  trough,  and  the  porous  vessel  which  should  be  flat  is 
placed  within  the  zinc,  so  that  the  platinum  in  it  may  be  con- 
nected with  the  zinc  of  the  neighboring  pair,  as  represented  in 
figure  556. 

zzz,  Are  the  zinc  plates  of  Fig.  556. 

the  form  of  figure  555.  s-\  ^ 

aaa,  Porous  cells  filled  with       '      ^^ 
nitric  acid. 

ccc,  Plates  of  platinum 
united  to  the  zinc  at  top  by 
binding  screws. 

pp,  Are  partitions.  The  di- 
visions of  the  battery  trough 
need  not  be  water  tight,  but 
merely  such  as  will  prevent  the  zincs  from  touching  one  another. 

It  will  be  seen  that  by  this  means  any  number  of  pairs  may  be 
easily  arranged.  Care,  however,  must  be  taken,  when  fitting  up 
such  an  arrangement,  that  the  platinum  be  kept  closely  connected 
with  the  zinc  by  a  large  surface,  otherwise  the  platinum  will  be 
fused  at  the  connections.  A  flat  piece  of  wood,  with  a  groove  to 
fit  the  zinc,  is  often  made  the  means  of  keeping  the  two  metals 
together,  but  we  prefer  flat  binding  screws  of  brass,  for  if  kept 
clean  they  assist  the  connection,  being  good  conductors.  The 
fusion  of  the  platinum  connections,  a  practical  and  often  expensive 
annoyance,  may,  however,  be  completely  prevented  by  coating 
about  half  an  inch  of  the  end  of  the  platinum,  either  with  copper 
or  silver,  which  is  easily  effected  by  the  electro-process :  the  coated 
part  is  then  connected  with  the  zinc  by  any  convenient  means 
without  the  risk  of  fusing. 

Figure  557  represents  a  section  of  Mr.  Grove's  nitric  acid  bat- 
tery, in  a  series  of  four  pairs  of  zinc  and  platinum.  The  outer 
thick  line,  A  B  c  D,  is  an  earthenware  trough,  which  is  divided 
into  four  cells.  The  dotted  lines  represent  four  porous  vessels,  of 
a  size  sufficient  to  contain  about  double  the  quantity  of  liquid  that 
is  contained  between  the  outer  surfaces  of  the  porous  vessels  and 
the  earthenware  cells.  The  dark  central  lines  are  the  plates  of 
amalgamated  zinc ;  and  the  thinner  lines,  that  bend  round  under 
the  porous  cells,  show  the  position  of  the  platinum  foil,  which  is 
attached  to  the  zinc  plate  by  small  screws. 

This  form  of  battery  is  also  free  from  some  of  the  objections  to 
the  common  battery,  but  it  is  seldom  or  never  used  in  the  ordinary 
processes  of  electro-metallurgy.  Its  advantages  over  every  other 
known  form  of  battery  are,  its  great  activity  of  action,  and  inten- 
sity or  power  of  current — a  circumstance  not  generally  sought 
after  by  electro-metallurgists.  But  if  it  were  duly  considered  that 
a  battery  consisting  of  three  pairs  of  zinc  and  platinum  is  far 
more  effective  than  an  ordinary  battery  of  ten  or  twelve  pairs 


526 


THE   PEACTICAL   METAL- WORKER'S  ASSISTANT. 


(although  the  elements  of  its  construction  are  more  expensive),  it 
would  stand  a  fair  chance  of  being  adopted  as  the  more  economical 
battery  of  the  two. 

Fig.  557. 


The  porous  cells  have  not  the  objection  of  being  closed  up  by 
the  deposition  of  metals  upon  or  within  them ;  but  they  are  affected 
by  the  acids,  and  by  long  working  they  become  too  porous,  the 
nitric  acid  passing  through  and  causing  rapid  destruction  of  the 
zinc.  It  wants  the  constancy  of  Daniell's,  its  quantity  declining 
rapidly  when  long  in  action — one  feature  we  have  often  experi- 
enced which  we  have  not  seen  observed  by  other  experimenters. 
When  working  with  a  Grove's  battery  of  from  eight  to  twelve 
pairs,  the  platinum  being  six  inches  by  seven  inches,  after  the  bat- 
tery was  in  action  for  four  or  five  hours,  during  which  it  dimin- 
ished in  quantity  gradually,  all  of  a  sudden  it  seemed  to  recover 
its  energy,  giving  a  quantity  and  power  not  much  less  than  it  gave 
in  the  first  hour,  and  then  declined  again  rapidly,  but  occasionally 
renewing  its  vigor  for  short  periods.  We  have  thought  it  proba- 
ble that  this  reaction  may  be  caused  by  the  formation  of  nitrate 
of  ammonia  in  the  rapid  decomposition  of  the  nitric  acid  during 
the  first  action  of  the  battery,  which,  as  it  accumulates,  may  be 
reacted  upon. 

The  prevailing  and  permanent  objection  to  the  use  of  this 
arrangement,  not  only  for  manufacturing  purposes,  but  for  many 
experimental  purposes,  is  this,  that  it  emits  nitrous  fames  which 
corrode  every  thing  within  their  reach,  and  prove  very  disagreeable 
to  every  person  breathing  them.  For  a  small  single  pair  of 
Grove's  battery  it  is  very  convenient  to  use  a  circular  form,  in 
which  case  a  little  cylinder  of  wood,  bored  so  that  its  sides  be 
about  £th  of  an  inch "  thick,  does  well  for  a  porous  cell,  and  will 
last  a  long  time. 

BUNSEN'S  BATTERY  is  a  modification  of  Groves'  and  much  used 
on  the  continent  for  electrical  purooses.  Carbon  is  used  instead 


DESCRIPTION   OF   GALVANIC   BATTERIES.  527 

of  the  platinum,  and  for  convenience  it  is  generally  made  cylin- 
drical. The  mode  of  construction  is  to  form  a  hollow  cylinder  by 
coking  pounded  coal  in  an  iron  mould,  then  soaking  the  coke  cyl- 
inder in  a  solution  of  sugar  and  calcining  a  second  time,  which 
gives  great  compactness.  The  porous  cell  containing  the  zinc  and 
dilute  acid  is  placed  in  this  cylinder,  and  the  whole  put  into  a 
glass  or  stoneware  vessel  charged  with  nitric  acid ;  of  course  the 
coke  cylinder  and  zinc  are  connected,  and  thus  the  battery  is  com- 
pleted.* Nitrous  fumes  are  evolved  from  this  battery  also. 

SMEE'S  BATTERY. — Some  of  the  defects  in  the  common  battery 
of  zinc  and  copper  were  much  lessened  by  an  ingenious  contrivance 
of  Mr.  Alfred  Smee.  This  gentleman  had  observed  that  if  the 
copper  plate  of  the  battery  be  roughened,  either  by  corrosive  acids 
or  by  rubbing  the  surface  with  sand  paper,  its  action  was  made 
much  more  efficient,  the  rough  surface  evolving  the  hydrogen 
much  more  freely. '  Taking  advantage,  therefore,  of  this  prin- 
ciple, he  covered  platinum  foil  with  a  finely  divided  black  powder 
of  platinum,  deposited  by  electricity  from  a  solution  of  that  metal, 
and  used  this  in  place  of  the  copper  in  the  ordinary  battery.  In- 
stead of  platinum  foil,  Mr.  Smee  soon  after  adopted  silver  foil, 
which  is  much  less  expensive.  The  method  of  preparing  these 
plates  is  given  by  Mr.  Smee  as  follows : — "  The  silver  to  be  pre- 
pared for  this  should  be  of  a  thickness  sufficient  to  carry  the  cur- 
rent of  electricity,  and  should  be  roughened  by  brushing  it  over  with 
a  little  strong  nitric  acid,  so  that  a  frosted  appearance  is  obtained. 
It  is  then  washed  and  placed  in  a  vessel  with  dilute  sulphuric  acid, 
to  which  a  few  drops  of  nitro-muriate  of  platinum  has  been  added. 
A  porous  tube  is  then  placed  into  this  vessel  with  a  few  drops  of 
dilute  sulphuric  acid  ;  into  this  tube  a  piece  of  zinc  is  put,  contact 
being  made  between  the  zinc  and  silver ;  the  platinum  will,  in  a 
few  seconds,  be  thrown  down  upon  the  silver  as  a  black  metallic 
powder.  The  operation  is  now  completed,  and  the  platinized 
silver  ready  for  use."f  A  simple  method,  which  obviates  the  use 
of  a  battery  is  thus  described :  lay  the  silver  between  two  pieces 
of  sand  paper,  and  press  it  with  a  common  smoothing  iron,  then 
pull  the  silver  out  while  under  the  pressure.  The  platinum  solu- 
tion is  made  very  hot,  and  the  silver  dipped  in  it  for  some  time, 
which  effects  the  coating. 

The  nitro-muriate  of  platinum  is  easily  prepared:  take  one  part 
of  nitric  acid,  and  two  parts  of  hydrochloric  acid  (muriatic  acid) ; 
mix  together  and  add  a  little  platinum,  either  as  metal  or  sponge ; 
keep  the  whole  at  or  near  a  boiling  heat ;  the  metal  is  then  dis- 
solved ;  forming  the  solution  required. 

*  A  more  simple  and  less  expensive  modification  of  this  arrangement,  is  to 
pat  a  solid  bar  of  carbon  or  coke  into  a  porous  cell  filled  with  nitric  acid, 
which  is  placed  in  a  stone  or  glass  jar  filled  with  dilute  sulphuric  acid,  hav- 
ing a  cylinder  of  zinc  surrounding  the  porous  cell,  leaving  about  one  inch  of 
space  between  the  porous  cell  and  zinc,  similar  to  a  Daniell's,  forming  a  mod- 
ification of  Grove's,  having  carbon  instead  of  the  platinum. 

t  Sinee's  Elements  of  Electro-Metallurgy,  2d  edition,  p.  24,  1843. 


528 


THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 


Fig.  558. 


Several  experiments  have  been  tried  with  a  view  to  substitute  a 
cheaper  metal  than  silver  to  deposit  the  platinum  upon,  but  not 
with  much  success.  Cheap  metals  have  also  been  coated  with 
silver  by  the  electro-process,  and  been  used  for  depositing  the  pla- 
tinum upon.  The  most  successful  is  a  composition  metal  made  of 
tin,  lead,  and  a  little  antimony,  rolled  into  sheet  and  plated  by  silver; 
this  was  found  very  convenient,  because  it  could  be  easily  bent 
into  any  required  shape,  and  it  keeps  its  place  without  the  neces- 
sity of  fixing  in  frames  as  required  by  thin  silver ;  nevertheless, 
for  constant  work  these  plates  are  found  not  to  present  any  per- 
manent advantage,  and  have  been  abandoned ;  besides,  to  give  a 
sufficient  coating  of  silver,  becomes  as  expensive  as  silver  foil. 

Mr.  Smee,  in  constructing  his  battery,  has  been  guided  by  the 
expense  of  the  silver,  and  therefore  reverses  the  order  of  arrange- 
ment introduced  by  Wollaston,  by  surrounding  the  platinized  silver 
with  the  zinc.  Fig.  558  represents  a  single  cell  of  this  form  of  bat- 
tery. A,  is  the  jar  containing  the  solution,  z  z, 
the  two  amalgamated  zinc  plates,  s,  the  platinized 
silver  plate.  The  whole  are  suspended  by  a  cross 
bar  of  wood;  and  as  it  is  essential  to  the  proper 
working  of  the  battery  that  the  plates  be  always 
parallel  to  one  another,  the  wooden  frame  is  gen- 
erally extended  round  the  edge  of  the  thin  silver 
plate,  though  it  is  not  so  represented  in  the  figure. 
One  of  the  clamps  at  the  top  of  the  wooden  bar 
is  connected  with  the  platinized  silver  plate,  and 
the  other  with  a  pair  of  zinc  plates.  Instead  of 
a  glass  or  stoneware  jar,  small  square  troughs, 
made  of  gutta  percha,  are  often  used  for  the 
Smee's  battery,  as  they  suit  admirably,  and  are 
not  liable  to  break. 
"When  intensity  of  electricity  is  required,  it  is  necessary  to  use  a 
number  of  such  cells,  which  may  be  arranged  in  a  wooden  frame, 
in  the  manner  shown  by  Fig.  559,  where  a  b  represent  the  two 
559  poles  of  the  battery,  and  c  c  the  wires  by 

which  the  cells  are  connected  with  one 
another. 

A  superior  form  of  compound  Smee's 
battery,  contrived  by  Acland,  is  repre- 
sented in  Fig.  560.  In  this  apparatus 
the  plates  are  all  connected  to  a  frame 
that  can  be  elevated  or  depressed  by 
means  of  an  iron  rod  and  rachet  wheel,' so  that  the  plates  may  be 
either  partially  or  entirely  immersed  in  the  solution,  or  raised  at 
pleasure  out  of  it.  The  connections  are  so  contrived,  that  by  a 
slight  alteration  the  battery  is  adapted  to  afford  either  quantity  or 
intensity  of  electric  power.  It  is  usually  made  to  contain  six  cells, 
any  number  of  which  can  be  used  at  once  that  a  given  process  may 
require.  The  exciting  fluid  is  contained  in  an  incorrodible  stone- 


.  ,   DESCRIPTION   OF   GALVANIC   BATTERIES.  529 

ware  trough,  placed  in  a  mahogany  box.  A  battery  of  this  des- 
cription, each  silver  plate  of  which  measures  20  square  inches,  has 
sufficient  power,  when  decomposing  water,  to  disengage  one  cubic 
inch  of  mixed  gases  in  50  seconds,  and  will  heat  to  redness  4  inches 
of  platinum  wire. 

Letter  B  in  Fig.  560  represents  an  apparatus  for  showing  the  de- 
Fig.  560. 


composition  of  water  into  oxygen  and  hydrogen  gas  by  the  voltaic 
battery. 

It  will  be  observed  in  Smee's  arrangement  that  there  are  two 
surfaces  of  zinc,  in  every  pair  exposed  to  the  acid,  which  do  not 
give  oft'  any  electricity,  but  when  long  in  use  are  much  acted  upon, 
forming  a  consideration  of  some  value  to  a  manufacturer. 

The  silver  used  is  very  thin,  and  liable  to  crack  when  taken 
from  its  frame,  and  therefore  cannot  be  made  into  different  con- 
structions of  battery  in  the  same  manner  as  we  can  do  with  cop- 
per. It  is  also  liable  to  have  zinc  deposited  upon  its  surface  when 
long  in  action. 

There  is  we  believe  no  arrangement  of  battery  better  known 
and  more  used  by  amateur  electrotypists  than  Smee's,  and  there 
are  probably  none  better  adapted  for  small  operations;  but  it  has 
not  been  introduced  to  any  extent  in  the  factory.  When  used  in 
series,  the  advantages  it  possesses  over  Wollaston's  do  not  counter- 
balance the  extra  labor  and  expense  attending  its  use,  and  many 
who  have  tried  it  in  the  operations  of  the  factory  have  for  those 
reasons  given  it  up. 

Numerous  modifications  of  these  different  batteries  have  been 
proposed  from  time  to  time,  intended  for  different  objects,  but  those 
given  embrace  all  that  are  used  for  electro-metallurgical  purposes. 
Owing  to  the  apparent  advantages  of  certain  forms  of  battery,  the 
following  may  be  referred  to : 

EARTH  BATTERY.— The  fact  that  when  a  piece  of  copper  and  a 


530  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

piece  of  zinc  are  imbedded  in  the  earth  and  connected  by  a  wire, 
there  is  a  current  of  electricity  obtained  from  them,  in  the  same 
way  as  if  they  were  placed  in  any  battery  trough,  instantly  sug- 
gested the  application  of  the  earth,  or  what  is  termed  an  earth 
battery,  to  the  purposes  of  depositing.  We  need  hardly  say  these 
trials  were  without  success.  The  electricity  obtained  in  this  way 
is  very  weak,  depending  wholly  upon  the  moisture  of  the  earth, 
and  the  arrangement  forming  therefore  simply  a  water  battery. 
We  have  made  electrotypes  by  this  means,  and  also  plated  small 
articles,  but  the  action  or  deposition  is  very  slow.  We  have  ob- 
tained a  greater  amount  of  deposition  in  five  minutes  from  one 
square  inch  of  zinc  and  copper  placed  in  dilute  sulphuric  acid, 
than  from  four  feet  of  zinc  and  copper  placed  in  the  earth  in  the 
space  of  an  hour.  An  earth  battery  adapted  to  deposit  from  150 
to  200  ounces  of  silver  per  day,  would  require  acres  of  land. 

In  this  as  in  all  other  forms  of  battery  the  deposit  is  in  relation 
to  the  zinc  oxidated  in  the  battery  ;  there  would  therefore  be  no 
economy  in  using  the  earth  battery,  and  to  lessen  the  amount  of 
surface  required  by  an  intensity  arrangement,  would  not  alter  the 
law,  but  rather  add  to  the  expense,  as  it  would  require  upwards  of 
100  pairs  in  the  earth  to  be  equal  to  3  or  4  pairs  of  Wollaston's 
for  the  object  of  depositing ;  and  would  thus  be  adding  to  the  cost 
of  depositing  one  hundred  times  the  equivalent  of  zinc  instead  of 
four  times  its  equivalent. 

MAGNETO-ELECTRIC  MACHINE. — Several  years  ago,  Mr.  Wool- 
rich,  of  Birmingham,  patented  a  discovery  for  applying  to  the 
deposition  of  metals  the  electricity  obtained  from  magnetism  or  the 
magneto-electric  current,  instead  of  voltaic  electricity.  We  have 
never  had  an  opportunity  of  operating  with  Mr.  Woolrich's  ma- 
chine, nor  of  seeing  it  in  operation  for  the  purpose  of  deposition. 
We  cannot  speak  of  it  from  experience ;  but,  from  a  statement 
made  at  the  meeting  of  the  British  Association  in  1850,  by  Mr. 
Elkington,  of  Birmingham,  who  is  the  proprietor  of  the  patent, 
and  a  gentleman  of  most  extensive  experience,  it  would  seem  that 
he  had  up  to  that  time  never  been  induced  to  give  up  the  ordinary 
battery  in  favor  of  magnetism  or  any  other  suggested  improve- 
ment. We  understand  however  that  this  means  of  obtaining  the 
electricity  for  the  purposes  of  electro-metallurgy  has  recently  been 
much  improved,  by  forms  of  magnets,  etc.,  patented  by  Mr.  Mill- 
ward,  and  described  by  him  as  follows  :  "  The  first  branch  of  the 
improvement  is  carried  into  effect  by  the  employment  of  an  electro- 
magnet formed  by  a  current  of  electricity  produced  from  a 
magneto-electric  machine,  instead  of  that  generated  in  a  voltaic 
battery;  and  such  an  electro- magnet  may  be  very  advantageously 
used  for  magnetizing  large  bars  of  steel,  or  for  producing  very 
powerful  magnets.  Any  of  the  known  forms  of  magneto-electric 
machines  will  serve  thus  to  convert  a  bar  of  steel  to  an  electro- 
magnet, but  the  patentee  prefers  to  use  one  composed  of  four, 
eight,  or  any  other  number  of  permanent  magnets,  having  double 


DESCRIPTION   OF   GALVANIC   BATTERIES.  531 

the  number  of  armatures,  and  coiled  with  strong  wire  of  about  60 
feet  in  length.  The  machine  about  to  be  described  has  been  found 
to  answer  well  in  practice.  In  this  machine  the  steel  magnets  are 
composed  of  eight  plates  of  a  U  form,  weighing  about  30  Ibs. 
each  plate,  and  there  are  eight  such  compound  magnets,  all  the 
north  poles  of  which  are  arranged  on  one  side  of  the  machine, 
and  the  south  poles  on  the  other  side,  although  this  precise  ar- 
rangement is  not  essential,  and  may  be  varied.  The  armatures  are 
of  soft  iron,  Aveighing  about  15  Ibs.,  and  are  coiled  about  with  60 
feet  of  copper  wire  of  No.  4  gauge,  and  insulated  in  the  usual 
manner.  The  armatures  revolve  in  a  brass  wheel,  and  are  caused 
to  pass  as  near  to  the  poles  of  the  magnets  as  practicable,  the  com- 
mutator or  break  acting  on  the  whole  eight  magnets  at  the  same 
instant,  so  that  the  current  of  electricity  shall  always  pass  in  one 
direction,  and  the  surface  of  the  whole  of  the  64  plates  be  in  com- 
bination at  the  same  time.  The  bar  of  soft  iron  used  as  the 
electro-magnet  with  this  machine  weighs  about  500  Ibs.,  and  is 
coiled  with  bundles  of  about  30  copper  wires  of  No.  16  gauge, 
and  about  60  feet  in  length  (the  bundles  are  formed  by  binding  a 
series  of  uncovered  wires  together  into  one  covered  strand  or 
bundle),  and  the  power  of  the  electro-magnet  will  depend  upon  the 
power  of  the  permanent  magnets  used  in  the  machine,  both  as  to 
the  weight  it  will  support  from  a  keeper,  and  as  to  its  capability 
of  rendering  bars  of  steel  permanently  magnetic  by  contact  there- 
with. It  will  therefore  be  evident  that  by  having  two  sets  of  the 
permanent  magnets,  and  changing  them  in  such  machine,  their 
supporting  power  may  be  increased  by  continued  charges  or  passes 
from  the  electro-magnet  thus  produced.  In  one  form  of  electro- 
magnetic machine  represented  and  described  under  the  second 
head  of  the  invention,  the  steel  bars  or  permanent  magnets  are 
eight  in  number  (these  bars  may  be  of  cast  or  soft  iron,  but  when 
soft  iron  is  employed,  bars  of  steel  permanently  magnetized  will 
have  to  be  used  in  conjunction  with  them),  of  a  U  form,  and  ar- 
ranged around  a  circle  with  their  poles  pointing  towards  the  centre. 
Each  arm  of  each  of  the  magnets  has  attached  to  it  straight  bars 
of  steel,  also  rendered  permanently  magnetic  (of  which  any  desired 
number,  and  of  any  length  or  size,  may  be  employed,  according  to 
the  strength  of  magnet  required),  which  are  so  placed  as  to  be  out 
of  the  influence  of  the  armatures  when  the  latter  are  revolving. 
The  poles  of  the  U-shaped  magnets  are,  on  the  contrary,  as  nearly 
as  possible  in.  contact  with  the  armatures  which  revolve  within  the 
circle  formed  by  them,  either  between  the  poles  or  in  front  of  them. 
Instead  of  the  bars  which  form  the  circle  being  of  steel  and  mag- 
netized, they  may  be  made  of  soft  iron,  and  depend  for  their  mag- 
netism upon  the  magnetic  bars  before  named  placed  around  them. 
In  another  form  of  machine  both  the  magnets  and  armatures  are 
stationary,  and  the  commutator  alone  has  motion  between  the  poles 
of  the  horse-shoe  magnets  and  the  armatures,  being  mounted  on  a 
spindle  and  caused  to  revolve  by  a  band  from  some  driving  ma- 


532 


THE   PKACTICAL   METAL-WORKER'S   ASSISTANT. 


chinery.  The  commutator,  or  break-piece,  is  composed  of  a  brass 
centre,  with  four  radial  arms  of  soft  iron,  either  solid  or  formed 
of  two  or  more  plates." — See  Repertory  of  Patent  Inventions,  vol.  18, 
for  1851,  and  Sketches  therein. 

The  quality  of  these  machines  for  depositing  depends  much  upon 
their  sustaining  power.  Eight  of  these  sets  of  plates  or  magnets, 
containing  altogether  about  12  cwt.  of  steel,  in  a  proper  state  of 
working,  are  said  to  form  a  battery  capable  of  depositing  from  12 
to  20  ounces  of  silver  per  hour,  but  it  is  not  stated,  however,  upon 
what  extent  of  surface  this  takes  place.  The  relative  economy  of 
these  magnets  over  the  galvanic  battery  has  not  been  so  great  as 
to  recommend  their  general  adoption.  We  have,  however,  no 
doubt  that,  as  such  a  machine  gives  electricity  of  great  intensity,  it 
may  be  superior  to  the  galvanic  battery  for  some  purposes,  and 
may  give  properties  to  the  deposited  metals  which  the  ordinary 
battery  does  not.* 

Before  concluding  the  description  of  batteries,  we  may  briefly 
notice  one  or  two  little  conveniences  which  are  indispensable  to  the 
operation.  The  first  of  these  is  what  are  termed  binding  screws,  by  ' 
which  the  parts  of  batteries,  as  we  have  shown  by  numerous  figures, 
are  connected  together,  or  by  which  their  poles  are  connected  to 
the  objects  through  which  the  voltaic  current  is  to  be  passed.  They 
are  usually  made  of  brass,  and  of  various  forms,  according  to  the 
shape  of  the  objects  that  are  to  be  connected. 

Figures  561  to  566  represent  some  of  the  most  useful  kinds;  Fig. 

F}  561  is  used  to  connect 

561    562     563        664        565          566.          wires  together;  Figs  563 

and  5  60  are  required  ior 
Smee's  battery  (see  Fig. 
559);  Kg  565  to  con- 
nect  the  plates  of  Grove  s 
battery  (Fig.  557) ;  Figs. 
563  and  564  are  used  for 
Daniell's  battery;  the  latter  for  connection  with  a  zinc  rod,  the 
Figs.  567  568.  . 


*  For  some  particulars  of  the  working  of  electro-magnetic  machines,   see 
Shaw's  Manual  of  Electro-Metallurgy,  2d  edition,  1843. 


ELECTROTYPE   PROCESSES.  533 

former  to  bind  plates  together.     In  all  cases,  the  parts  that  touch 
the  surfaces  to  be  connected  must  be  perfectly  clear  and  bright. 

In  many  cases,  when  a  complicated  apparatus  has  been  put 
together,  it  is  desirable  to  ascertain  whether  the  connections  are 
all  perfect.  This  is  best  determined  by  means  of  a  galvanometer, 
two  varieties  of  which  are  represented  by  Figs.  567  and  568. 


CHAPTEE  XXVI. 

ELECTROTYPE   PROCESSES.        • 

SINGLE-CELL  OPERATIONS. — "We  shall  now  proceed  to  detail 
the  process  of  electrotyping,  the  materials  for  which  are  of  the 
most  simple  nature.  Let  us  suppose  that  the  object  of  the  student 
is  to  copy  a  copper  medal — for  example,  the  side  of  a  penny-piece. 
Dissolve  a  quantity  of  the  crystals  of  sulphate  of  copper  in  any- 
convenient  vessel;  if  distilled  water  can  be  had,  the  better.  This 
is  conveniently  done  by  suspending  the  crystals  in  a  coarse  cloth 
on  the  surface  of  the  water,  or  the  crystals  may  be  put  into  the 
water,  and  well  stirred,  till  dissolved ;  crushing  the  crystals  facili- 
tates their  solution.  The  water  should  be  kept  cold  and  be  fully 
saturated  with  the  salt,  and  the  solution  allowed  to  stand  untouched 
for  several  hours.  This  last  precaution  is  not  always  essential,  but 
only  necessary  when  the  copper  solution  is  not  perfectly  clear  and 
transparent. 

The  sulphate  of  copper  of  commerce  has  often  a  large  quantity 
of  iron  in  it,  a  portion  of  which  becomes  per-oxidized,  and  will 
precipitate  or  fall  to  the  bottom  of  the  solution  on  standing ;  in- 
deed, when  it  is  known  that  the  salt  contains  much  iron,  it  is  best 
to  crush  the  salt  very  fine,  and  expose  it  to  the  air  for  some  time; 
when  dissolved,  after  this  exposure,  a  great  quantity  of  iron  will 
settle  at  the  bottom  of  the  solution,  which  should  be  carefully 
decanted  and  the  last  portion  filtered.  The  clear  solution  should 
now  have  about  one-fourth  of  its  quantity  of  water  added  to  it,  as 
a  completely  saturated  solution  is  not  the  best.  A  newly-formed 
solution  does  not  deposit  so  freely  as  one  that  has  been  in  use  for 
some  time.  The  addition  of  a  few  drops  of  sulphuric  acid,  or,  what 
we  have  found  better,  a  little  sulphate  of  zinc — about  one  ounce  to 
the  pound  of  sulphate  of  copper — improves  the  condition  of  a  new 
solution. 

Next,  put  the  solution  of  sulphate  of  copper  into  the  vessel  in- 
tended for  use,  say  it  is  a  large  jelly-pot,  in  which  let  a  vessel  of 
unglazed  porcelain  (porous  vessel)  be  placed,  filled  to  within  half 
«,n  inch  of  the  mouth  with  a  mixture  of  2-i  parts  water  and  1  sul- 
phuric acid,  taking  care  that  the  copper  solution  is  of  the  same 
depth  as  the  solution  in  the  porous  cell. 


«534  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

PREPARATION  OF  THE  COIN. — A  fine  copper  wire  must  now  be 
put  round  the  edge  of  the  coin  and  fastened  by  twisting.  Then 
CDver  the  back  part,  upon  which  the  deposit  is  not  required,  with 
beeswax  or  tallow,  or,  what  is  better,  imbed  the  back  of  the  coin 
with  gutta  percha.  Have  the  fore  part  or  face  well  cleaned,  and 
the  surface  moistened  with  sweet  oil,  by  a  camel's  hair  pencil,  and 
then  cleaned  off  by  a  silk  cloth,  till  the  surface  appears  dry ;  or, 
instead  of  oil,  the  surface  may  be  brushed  over  with  black  lead,  which 
will  impart  to  it  a  bronze  appearance.  The  use  of  the  oil  or  black 
lead  is  to  prevent  the  deposit  adhering  to  the  face  of  the  coin.  A 
very  common  and  excellent  method  to  prevent  the  copper  deposit 
adhering  to  the  copper  mould  is  this : — Take  a  gill  of  rectified 
spirits  of  turpentine,  and  add  to  it  about  the  size  of  an  ordinary 
pea  of  beeswax.  When  this  is  dissolved,  wet  over  the  surface  of 
the  mould  with  it,  and  then  allow  it  to  dry :  the  mould  is  then 
ready  to  put  into  the  solution.  Medals  take*i  from  moulds  so  pre- 
pared retain  their  beautifully  bright  color  for  a  long  time.  But 
when  fine  line  engravings  are  to  be  coated,  the  little  wax  dissolved 
in  the  turpentine  may  be  objectionable ;  so  also  is  black  lead,  for 
both  have  a  tendency  to  fill  up  the  fine  lines.  In  this  case,  let  the 
wash  with  turpentine  be  wiped  off  by  a  silk  handkerchief,  instead 
of  drying  it :  but  for  ordinary  medals  this  objection  will  scarcely 
apply.  This  being  done,  the  opposite  end  of  the  copper  wire 
round  the  penny-piece  is  to  be  connected  with  a  piece  of  amalga- 
mated zinc,  either  by  means  of  a  binding  screw  or  a  hole  in  the 
zinc.  Then  place  the  zinc  in  the  acid  within  the  porous  cell,  and 
put  the  penny-piece  into  the  copper  solution :  bring  the  face  of  the 
coin  parallel  to  the  zinc,  at  the  distance  of  about  half  an  inch  or 
one  inch  from  the  porous  vessel.  Deposition  immediately  begins, 
and  the  metal  thickens  according  to  the  length  of  time  the  action 
is  kept  up.  In  about  twenty-four  hours,  the  deposit  will  be  of  the 
thickness  of  a  common  card,  and  it  may  then  be  taken  off.  The 
zinc  is  to  be  brushed  and  washed,  before  it  is  put  aside.  The  wire 
round  the  coin  is  now  to  be  untwisted,  and  by  a  slight  turn  will 
come  off  easily.  The  deposit  is  also  easily  separated  from  the 
mould,  which  will  be  a  perfect  counterpart  of  the  face  of  the  penny- 
piece. 

This  mould  is  next  to  be  treated  exactly  as  described  for  obtain- 
ing it  from  the  penny-piece,  and  the  deposit  from  it  will  be  a  fac- 
simile of  one  side  of  the  penny-piece.  With  care,  any  number  of 
duplicates  may  be  taken  from  this  mould. 

It  need  hardly  be  remarked,  that  as  copper  is  deposited  the 
solution  becomes  proportionally  exhausted,  and  in  a  short  time  the 
current  of  electricity  passing  will  be  too  much  for  the  strength  of 
the  solution,  which  will  then  give  a  deposit  of  a  sandy  consistence, 
without  tenacity.*  It  is  therefore  necessary,  while  the  deposition 
is  going  on,  to  suspend  some  crystals  of  sulphate  of  copper  at  the 

*  See  Laws  of  Deposition,  page  20. 


ELECTROTYPE   PROCESSES. 


585 


top  of  the  solution,  which,  as   they  dissolve,  will  maintain  its 
strength. 

FORMS  OF  APPARATUS. — It  will  be  observed  that  no  particular 
form  of  apparatus  is  required  for  electrotyping,  but  certain  modi- 
fications may  be  adopted  for  convenience  and  economy.  As  every 
portion  of  the  zinc  in  the  acid  is  capable  of  giving  off  electricity, 
by  placing  the  cell  that  contains  the  zinc  in  the  centre  of  the  cop- 
per solution,  moulds  may  be  suspended  on  each  side  of  that  cell. 
We  have  also  observed  that  the  zinc  plate  should  not  be  allowed 
to  touch  the  cell,  as  the  copper  will  be  reduced  upon  it  and  the 
cell  destroyed.  To  avoid  this,  the  zinc  may  be  suspended  by  a 
small  wooden  peg,  put  through  it  and  made  to  rest  upon  the  edges 
of  the  cell.  Figures  569, 570,  571,  572,  represent  several  convenient, 
forms  of  apparatus  for  electrotyping. 


Figs.  569 


570 


571. 


Fig.  572. 


Fig.  572  is  a  form  of  the  apparatus  which  the  author  has  used 
for  many  years  with  great  success,  being  both 
cheap  and  effective,  a  is  a  large  jelly-pot  hold- 
ing the  copper  solution;  b  is  a  flat  porous  cell, 
about  4  inches  square  and  half  inch  wide;  z 
the  zinc  plate.  Amalgamated  metals  may  be 
suspended  upon  both  sides,  and  the  strength 
of  the  solution  is  maintained  by  suspending  a 
few  crystals  of  the  salt  in  a  little  cloth  bag 
upon  the  surface  of  the  solution. 

Instead  of  porous  vessels  made  of  earthenware,  a  bladder  may 
be  used,  in  which  the  acid  and  zinc  are  placed.  We  have  also 
seen  a  vessel  divided  by  a  porous  partition,  being  either  a  plate  of 
biscuit  porcelain,  plaster  of  Paris,  very  thin  sycamore  wood,  or 
dressed  skin.  The  porcelain,  as  before  mentioned,  is  the  best: 
plaster  is  too  porous,  and  the  solution  soon  destroys  it :  wood  is 
too  close,  and  the  deposit  is  consequently  very  slow :  skin  doe? 
very  well  for  a  short  time,  but  it  is  soon  destroyed.  When  porous 
cells  were  not  convenient,  we  have  made  electrotypes  by  wrapping 
the  zinc  plates  in  two  or  three  folds  of  stout  cartridge  paper,  moist- 
ened with  a  solution  of  salt,  and  placing  this  in  the  copper  solution 
with  the  mould.  Of  course,  this  is  only  to  be  adopted  when  a 
porous  vessel  cannot  be  obtained.  The  paper  lasts  but  a  short 


536  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

time,  and  has,  therefore,  to  be  frequently  renewed ;  besides  which, 
there. is  always  a  deposit  of  copper  upon  the  paper,  thus  occasion- 
ing a  loss. 

Common  coarse  garden-pots  answer  excellently  for  porous  vessels, 
closing  the  aperture  at  bottom  by  a  cork. 

The  precautions  that  have  been  given  (see  Darnell's  Battery,  p. 
39),  as  to  the  preserving  of  the  porous  cells  when  not  in  use,  are 
applicable  to  the  cells  or  partitions  used  in  these  processes,  which, 
when  not  in  use,  should  be  kept  in  water,  or  should  not  be  allowed 
to  dry  until  they  have  been  in  water  long  enough  to  dissolve  out 
the  salts  that  were  within  the  pores  of  the  cell ;  otherwise  the  salts 
crystallize,  and  either  crack  the  cell  or  cause  it  to  scale  off'  in  small 
pieces.  Porous  cells,  when  not  thoroughly  washed  and  freed  from 
salts,  if  laid  aside  for  a  few  days,  often  thrown  out  an  efflorescence, 
or  crystalline  growth,  like  mould,  of  a  soft  silky  texture,  and  from 
one-half  to  one  inch  in  length.  An  analysis  of  this  efflorescent 
matter  gave 

Oxide  of  zinc  .  .*:  ,  f"'"  .  39'6 
Sulphuric  acid .  .  .  J  -.  26'0 
Water  .  . ..  -  ..  .  •  ,  34-2 

99-8 

COMPARATIVE  VALUE  OF  EXCITING  SOLUTIONS. — We  have 
recommended  the  porous  cell  being  filled  by  dilute  sulphuric  acid, 
which  we  consider  best ;  but  other  saline  solutions  will  serve  the 
same  purpose :  solutions  of  common  salt,  sal  ammoniac,  sulphate 
of  zinc,  have  been  recommended,  and  each  has  been  called  best  in 
its  turn.  The  following  results  of  experiments  with  these  solu- 
tions in  the  porous  cell  will  show  their  relative  qualities,  and  enable 
the  student  to  judge  for  himself.  The  size  of  the  zinc  plate  in  the 
cell  used  in  these  experiments  measured  6  inches  by  6  inches ;  the 
copper  plates  upon  which  the  deposits  were  formed  were  the  same 
size;  the  solution  of  copper  was  kept  at  the  same  strength;  the 
time  that  each  was  in  solution  was  16  hours. 


ELECTROTYPE   PROCESSES. 


537 


Solution  in  porous  Cell. 

Zinc  dissolved. 

Copper  deposited. 

/Sal  ammoniac. 

oz.     dwt.     gr. 

oz.     dwt.     gr. 

Saturated  solution     .... 

1         5       14 

1         2       12 

1  part  saturated  solution  ) 
1  part  water     .     .     .     .    j 

185 

1         3  ^    10 

1  part  saturated  solution    ) 
3  parts  water    .     .     .     .    j 

0      12      13 

0      10      17 

Common  Salt. 

Saturated  solution     .... 

0      16        3 

0      14      12 

1  part  saturated  solution  ) 
1  part  water      ....*) 

0      18        9 

0      17        8 

1  part  saturated  solution    ) 
3  parts  water    .     .     .     .    j 

105 

0       19       16 

Sulphate  of  Zinc. 
Saturated  solution      .     .     .     . 

1        3      18 

0      19        0 

1  part  saturated  solution 
1  part  water     .     .     .     . 

108 

0      19      18 

1  part  saturated  solution 
3  parts  water   .... 

0      14      16 

0      14        8 

Sulphuric  Acid. 

1  part  to  8  of  water  .... 

316 

148 

1  part  to  16  of  water     .     .     . 

2      11        8 

218 

1  part  to  24  of  water     .     .     . 

2        1        3 

256 

How  OFTEN  SOLUTIONS  SHOULD  BE  CHANGED  AND  ZINC  AMAL- 
GAMATED.— Students  have  often  put  this  question  to  us :  How  often 
should  the  solution  in  the  cell  be  renewed,  and  the  zinc  plate  be 
amalgamated  ?  The  following  are  the  results  of  many  trials  made 
to  ascertain  the  facts  necessary  to  answer  this  inquiry.  The  zinc 
plates  used  were  nearly  one  foot  square,  and  the  copper  plate  upon 
which  the  deposit  was  made  was  of  the  same  size  as  the  zinc  plates. 

In  the  first  series  the  zinc  plates  were  not  taken  out  either  to 
brush  or  re-amalgamate,  neither  were  the  solutions  renewed  during 
the  time  specified. 


2  Ib.  common  salt  in  one 
gallon  of  water 


24  hours 
48  hours 
60  hours 

ours 


2  Ib.  sulphate  of  zinc  in  one  j 

gallon  of  water  }  60  Ilour3 

1  Ib.  sulphuric  acid  to  24  j  24  hours 

of  water  1  48  hours 


Copper 
deposited. 

Zinc 

dtaotot 

oz.        dwt. 

or..       dwt. 

12       9 

12     17 

17     13 

20    17 

24    15 

34      3 

9     13 

9     18 

16      4 

17     10 

23     10 

24       8 

15     17 

17     15 

27     16 

32      3 

538  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

From  these  results  it  is  evident  that  the  best  and  most  economi- 
cal manner  of  treating  the  solution  and  the  zinc  would  be  to  renew 
the  solution  every  24  hours,  as  the  second  24  hours  do  not  give, 
without  renewal,  above  half  the  deposit  of  the  first  24  hours,  while 
the  waste  of  zinc  is  very  little  less  than  in  the  first. 

The  next  series  of  experiments  was  with  the  same  zinc  and  the 
same  kind  of  solutions,  but  the  zinc  was  taken  out  every  24  hours, 
and  brushed,  but  not  re-amalgamated,  and  put  back  again  with  new 
solution  in  the  porous  cell. 

Copper  Zinc 

deposited.  dissolved, 

oz.        dwt.  07..       dwt. 

Salt  and  water  .  4  days  of  24  hours  .  49  16  51  8 
Sulphate  of  zinc  .  4  days  of  24  hours  .  47  14  48  9 
Acid  and  water  .  3  days  of  24  hours*  .  48  13  53  7 

These  results  give  the  most  ample  reply  to  the  question  so  often 
put,  and  will  guide  the  manufacturer  as  well  as  the  student  in  his 
operations,  whether  time  or  material  be  of  the  greatest  consequence 
to  him. 

We  may  remark  that  the  sulphate  of  zinc  solution  does  not 
require  renewal,  but  simply  that  we  half  empty  the  cell  and  refill 
it  with  water.  The  sulphate  of  zinc  poured  out  being  nearly  satu- 
rated, may  be  crystallized,  and  will  serve  for  other  electro-metal- 
lurgical operations. 

MAKING  OF  MOULDS. — The  directions  giving  for  obtaining  a 
mould  from  a  penny-piece,  by  deposition,  are  applicable  to  taking 
moulds  from  any  metallic  medal,  engraving,  or  figure  that  is  not 
undercut ;  and  for  depositing  within  the  moulds  so  produced.  On 
the  first  discovery  of  this  art,  the  electrotypist  was  confined  to 
metallic  moulds,  as  the  deposition  would  not  take  place  except 
upon  metallic  surfaces;  but  the  discovery  that  plumbago,  or  black 
lead  polished,  had  a  conducting  power  similar  to  that  of  metal,  and 
that  the  deposit  would  take  place  upon  its  surface  with  nearly  the 
same  facility  as  upon  metal,  freed  the  art  at  once  from  many  of  its 
trammels,  and  enabled  the  operator  to  deposit  upon  any  substance 
— wood,  plaster  of  Paris,  wax,  etc. — by  brushing  over  the  surface 
with  black  lead.  It  obliged  the  electro-metallurgist,  however,  to 
render  himself  expert  in  the  art  of  moulding,  since  no  good  elec- 
trotype can  be  obtained  without  a  perfect  mould.  We  shall,  for 
this  reason,  endeavor  now  to  give  such  instructions  as  will  enable 
the  student  to  make  good  moulds  after  a  very  short  practice ;  but 
we  need  hardly  add,  that  in  this  as  well  as  in  every  operation, 
however  plain  maybe  the  instructions  and  easy  the  manipulations, 
practice  is  necessary  to  ensure  success ;  so  that  the  student  ought 
not  to  lose  patience  should  his  first  attempt  not  succeed  to  his 
wishes.  The  substances  used  for  taking  moulds  from  objects  to 
be  copied  by  electrotype  are  beeswax,  stearine,  plaster  of  Paris, 
and  fusible  metal ;  recently,  gutta  percha  has  been  very  success- 
fully used.  The  articles  to  be  copied  are  generally  composed  either 


ELECTROTYPE  PROCESSES. 

of  plaster  of  Paris  or  metal.  Suppose,  in  the  first  place,  the  article 
to  be  copied  is  of  metal,  and  a  mould  is  to  be  taken  from  it  in  wax 
or  stearine.  The  latter  we  have  not  found  to  answer  well  alone; 
when  used  it  should  be  mixed  with  wax,  about  half-and-half. 

PREPARATION  OF  WAX. — Whether  the  beeswax  have  stearine 
in  it  or  not,  it  is  best  to  prepare  it  in  the  following  manner : — Put 
some  common  virgin  wax  into  an  earthenware  pot  or  pipkin,  and 
place  it  over  a  slow  fire;  and  when  it  is  all  melted,  stir  into  it  a 
little  white  lead  (flake  white) — say  about  one  ounce  of  white  lead 
to  the  pound  of  wax;  this  mixture  tends  to  prevent  the  mould  from 
cracking  in  the  cooling,  and  from  floating  in  the  solution:  the  mix- 
ture should  be  re-melted  two  or  three  times  before  using  it  for  the 
first  time. 

To  TAKE  MOULDS  IN  WAX. — The  medal  to  be  copied  must  be 
brushed  over  with  a  little  sweet  oil:  a  soft  brush,  called  a  painter's 
sash  tool,  suits  this  purpose  well :  care  must  be  taken  to  brush  the 
oil  well  into  all  parts  of  the  medal,  after  which  the  superfluous  oil 
must  be  wiped  off  with  a  piece  of  cotton  or  cotton  wool.  If  the 
medal  has  a  bright  polished  surface,  very  little  oil  is  required,  but 
if  the  surface  be  matted  or  dead,  it  requires  more  care  with  the  oil. 
A  slip  of  card-board  or  tin  is  now  bound  round  the  edge  of  the 
medal,  the  edge  of  which  slip  should  rise  about  one-fourth  of  an 
inch  higher  than  the  highest  part  on  the  face  of  the  medal :  this 
done,  hold  the  medal  with  its  rim  a  little  sloping,  then  pour  the 
wax  in  the  lowest  portion,  and  gently  bring  it  level,  so  that  the 
melted  wax  may  gradually  flow  over ;  this  will  prevent  the  forma- 
tion of  air  bubbles.  Care  must  be  taken  not  to  pour  the  wax  on 
too  hot,  as  that  is  one  great  cause  of  failure  in  getting  good  moulds ; 
it  should  be  poured  on  just  as  it  is  beginning  to  set  in  the  dish. 
As  soon  as  the  composition  poured  on  the  medal  is  set  (becomes 
solid),  undo  the  rim,  for  if  it  was  allowed  to  remain  on  till  the  wax 
became  perfectly  cool,  the  wax  would  adhere  to  it,  and  being  thus 
prevented  from  shrinking,  which  it  always  does  a  little,  would  be 
liable  to  crack.  Put  the  medal  and  wax  in  a  cool  place,  and  in 
about  an  hour  the  two  will  separate  easily.  When  they  adhere, 
the  cause  is  either  that  too  little  oil  has  been  used,  or  that  the  wax 
was  poured  on  too  hot. 

Rosix  WITH  WAX. — Rosin  has  been  recommended  as  a  mixture 
with  wax;  mixtures  of  which,  in  various  proportions, we  have  used 
with  success;  but  when  often  used,  decomposition,  or  some  change 
takes  place,  which  makes  the  mixture  granular  and  flexible,  ren- 
dering it  less  useful  for  taking  moulds.  When  rosin  is  used,  the 
mixture,  when  first  melted,  should  be  boiled,  or  nearly  so,  and 
kept  at  that  heat  until  effervescence  ceases ;  it  is  then  to  be  poured 
out  upon  a  flat  plate  to  cool,  after  which  it  rnay  be  used  as  de- 
scribed. 

MOULDS  IN  PLASTER. — If  a  plaster  of  Paris  mould  is  to  be  taken 
from  the  metallic  medal,  the  preparation  of  the  medal  is  the  same 
as  described  above ;  and  when  so  prepared  with  the  rim  of  card- 


540  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

board  or  tin,  get  a  basin  with  as  much  water  in  it  as  will  be  suffi- 
cient to  make  a  proper  sized  mould  (a  very  little  experience  will 
enable  the  operator  to  know  this),  then  take  the  finest  plaster  of 
Paris  and  sprinkle  it  into  the  water,  stirring  it  till  the  mixture 
becomes  of  the  consistence  of  thick  cream;  then  pour  a  small  por- 
tion upon  the  face  of  the  medal,  and,  with  a  brush  similar  to  that 
used  for  oiling  it,  gently  brush  the  plaster  into  every  part  of  the 
surface,  which  will  prevent  the  formation  of  air-bubbles ;  then  pour 
on  the  remainder  of  the  plaster  till  it  rises  to  the  edge  of  the  rim : 
if  the  plaster  is  good,  it  will  be  ready  for  taking  oS'  in  an  hour. 
The  mould  is  then  to  be  placed  before  a  fire,  or  in  an  oven,  until  quite 
dry,  after  which  it  is  to  be  placed,  back  downwards,  in  a  shallow 
vessel  containing  melted  wax,  not  of  sufficient  depth  to  flow  over 
the  face  of  the  niQuld,  allowing  the  whole  to  remain  over  a  slow 
fire  until  the  wax  has  penetrated  the  plaster,  and  appears  upon  the 
face.  Having  removed  it  to  a  cool  place  to  harden,  it  will  soon  be 
ready  for  electrotyping.  If  the  mould  is  large  and  the  plaster 
thick,  the  wax  may  be  put  upon  the  surface,  and  only  as  much  as 
will  penetrate  a  small  way  into  the  plaster.  In  both  these  instances 
the  wax  used  is  generally  lost,  and  there  is  always  liability  of  the 
copper  solution  passing  through,  and  causing  what  is  termed  sur- 
face deposit,  making  the  face  of  the  medal  rough.  We  may  remark 
that,  although  occasionally  there  may  be  a  very  good  electrotype 
obtained  from  a  plaster  mould,  still  they  are  in  general  very  in- 
ferior ;  as  the  saturating  of  the  plaster  has  a  tendency  to  blunt  the 
impression,  and  the  wax  used  for  the  purpose  of  saturation  becomes 
expensive.  It  may  be  partially  recovered  by  boiling  the  plaster 
in  water:  the  wax  melts  out,  and  is  obtained  when  the  water  cools. 
Plaster  should  not  be  used  for  moulds  where  wax  can  be  employed, 
being  neither  so  good  nor  so  economical ;  but  there  are  cases  in 
which  the  moulds  being  very  large,  the  use  of  plaster  is  unavoid- 
able. 

MOULDS  IN  FUSIBLE  ALLOY.— The  next  means  of  taking  moulds 
is  by  fusible  metal.  This  name  is  given  to  alloys  of  two  or  more 
metals  which  melt  at  a  very  low  temperature ;  it  suits  the  purpose 
of  taking  moulds  of  small  objects  very  well.  The  following  are 
examples  of  such  compositions : 

Tin.  Lead.  Bismuth.  Zinc. 

1120 
1230 

1011 

These  all  melt  at  a  temperature  below  that  of  boiling  water. 
The  ingredients  are  melted  together  in  an  iron  ladle,  poured  out 
upon  a  flat  stone,  broken  up,  and  re-melted  in  the  same  way  two 
or  three  times,  in  order  that  they  may  be  thoroughly  mixed.  The 
medal  from  which  the  mould  is  to  be  taken  is  prepared  in  the 
same  manner  as  described  for  wax. 

The  fusible  alloy  is  melted  and  poured  into  a  saucer,  or,  what 


ELECTROTYPE   PROCESSES.  541 

does  better,  a  small  wooden  tray.  The  operator  now  watches  till 
it  cools  down  into  a  semifluid  state,  or  to  the  point  of  setting,  when 
he  brings  the  medal  suddenly  upon  it,  face  downwards,  and  holds 
it  there  until  the  alloy  has  fairly  set ;  he  then  allows  it  to  cool,  and 
undoes  the  slip  around  the  medal,  from  which  the  mould  will  easily 
separate.  The  height  of  the  slip  of  paper  above  the  surface  of 
the  medal  determines,  of  course,  the  thickness  of  the  mould.  The 
beginner  very  seldom  succeeds  in  his  first  attempts  at  making 
moulds  in  fusible  alloy ;  but  as  a  little  experience  teaches  more 
than  the  reading  of  an  essay  upon  the  subject,  he  will  soon  find 
both  his  patience  and  labor  rewarded  with  gratifying  success. 
Some  of  the  finest  moulds  are  taken  by  this  process,  but,  from  the 
constant  loss  of  the  materials  by  oxidation,  etc.,  it  is  expensive,  so 
that  its  use  amongst  electro-metallurgists  is  very  limited. 

MOULDS  IN  GUTTA  PERCHA. — Gutta  percha,  as  a  material  for 
moulding,  serves  the  purpose  most  admirably.  We  have  seen 
moulds  of  this  substance  equal  if  not  superior  to  any  that  we  ever 
saw  taken  in  wax,  and  of  a  depth  of  cutting  which  *it  would  have 
been  very  difficult  to  have  taken  in  wax.  The  method  adopted  for 
taking  moulds  is  to  heat  the  gutta  percha  in  boiling  water,  or  in  a 
chamber  heated  to  the  temperature  of  boiling  water,  which  makes 
it  soft  and  pliable.  The  medal  is  fitted  with  a  metallic  rim,  or 
placed  in  the  bottom  of  a  metal  saucer  with  a  cylindrical  rim  a 
little  larger  than  the  medal ;  the  medal  being  placed  back  down,  a 
quantity  of  gutta  percha  is  pressed  into  the  saucer,  and  as  much 
added  as  will  cause  it  to  stand  above  the  edge  of  the  rim.  It  is 
now  placed  in  a  common  copying-press  and  kept  under  pressure 
until  it  is  quite  cold  and  hard.  The  impressions  taken  in  this  way 
are  generally  very  fine.  When  the  medal  is  not  deep  cut  a  less 
pressure  may  suffice,  but  when  the  pressure  is  too  little  the  im- 
pression will  be  blunt. 

Gutta  percha  takes  a  coating  of  black  lead  readily,  and  the  de- 
posit goes  over  it  easily. 

A  mixture  of  gutta  'percha  and  marine  glue  has  been  recom 
mended  for  moulds  as  superior  to  gutta  percha  alone.  We  have 
not  had  an  opportunity  of  using  this  mixture,  but  have  every  con- 
fidence in  the  recommendations  given  of  it. 

MOULDS  FROM  FERNS,  SEA-WEED,  ETC. — A  method  of  taking 
impressions  of  fern-leaves  and  sea-weeds  has  recently  been  pro- 
posed by  Dr.  F.  Branson,  in  the  Athenseum.  It  is  thus  described : 

"A  piece  of  gutta  percha,  free  from  blemish,  and  the  size  of  the 
plate  required,  is  placed  in  boiling  water.  When  thoroughly 
softened  it  is  taken  out  and  laid  fiat  upon  a  smooth  metal  plate 
and  immediately  dusted  over  with  the  finest  bronze  powder  used 
for  printing  gold  letters.  The  object  of  this  is  threefold — to  drv 
the  surface,  to  render  the  surface  more  smooth,  and  to  prevent  ad- 
hesion. The  plant  is  then  to  be  neatly  laid  out  upon  the  bronze 
surface  and  covered  with  a  polished  metal  plate  either  of  copper 
or  of  German  silver.  The  whole  is  then  to  be  subjected  to  an 


542  THE   PRACTICAL   METAL-WORKERS   ASSISTANT. 

amount  of  pressure  sufficient  to  imbed  the  upper  plate  in  the  gutta 
percha.  When  the  gutta  percha  is  cold,  the  metal  plate  may  be 
removed  and  the  fern  gently  withdrawn  from  its  bed.  A  beauti- 
ful impression  of  the  fern  will  remain."  An  electrotype  may  be 
deposited  upon  the  bronzed  or  black  leaded  gutta  percha. 

We  have  seen  many  electrotype  leaves  done  by  this  method, 
which  were  certainly  very  pretty  as  electrotypes,  and  the  process 
is  well  adapted  for  flat  leaves ;  but  the  pressure  required  renders 
it  unsuitable  for  some  kinds  of  leaves — indeed,  it  destroys  the 
natural  forms  of  the  greater  number  both  of  leaves  and  sea- weeds. 
The  products  of  the  process  cannot,  indeed,  be  compared  with 
those  electrotype  leaves  the  moulds  of  which  are  taken  by  wax. 
The  great  merit  of  the  process  is  its  ease  and  simplicity.  The 
method  given  for  taking  the  mould  of  the  leaf  is  suitable  for  any 
kind  of  flat  mould  in  gutta  percha.  The  mould  of  a  leaf  may  be 
taken  in  plaster  by  placing  the  leaf  upon  dry  sand  and  pressing 
the  sand  under  and  on  each  side  to  fill  up  the  spaces  under  the 
leaf  so  as  to  bear  the  pressure  of  the  plaster,  putting  a  collar  of 
paper  round  the  sand  to  prevent  its  yielding,  and  then  pouring  the 
plaster  over  the  whole.  When  the  plaster  is  set,  the  leaf  is  re- 
moved and  the  plaster  trimmed  round  with  a  knife.  This  also  has 
its  difficulties ;  for  when  leaves  have  hairs  upon  them  they  stick 
into  the  plaster.  The  method  of  taking  moulds  of  leaves  in  wax 
is  by  holding  the  leaf  in  the  hand  and  brushing  a  thin  layer  of 
melted  wax  over  the  surface  to  be  moulded;  allowing  this  to 
harden,  and  then  brushing  on  another  layer — and  so  on  until  the 
wax  is  sufficiently  thick  to  suffer  handling.  The  leaf  is  then  gently 
drawn  off  the  wax,  which  is  to  be  black-leaded,  and  put  into  the 
electrotype  apparatus  to  receive  the  coating  of  copper.  A  type 
of  the  leaf  is  by  this  means  obtained  with  all  its  natural  convo- 
lutions. 

NATURE  PRINTING. — A  further  improvement  upon  making 
moulds  of  leaves  and  other  vegetable  objects,  has  been  practised 
by  an  eminent  firm  in  London.  The  leaf  is  carefully  dried  and 
laid  upon  a  smooth  piece  of  milled  lead,  which  is  placed  between 
two  steel  plates,  and  passed  between  rollers,  these  press  the  leaf 
into  the  lead,  and  produce  a  complete  mould.  Copies  from  this 
may  be  taken  with  gutta  percha  or  electrotype.  Printed  impres- 
sions of  leaves,  sea  weed,  and  such  like  objects,  prepared  in  this 
way,  may  be  seen  in  an  excellent  work  published  by  Bradbury 
and  Evans,  and  a  full  detail  of  the  process,  with  specimens,  will  be 
found  in  the  proceedings  of  the  Royal  Institution  for  1854. 

CASTING  OF  REPTILES,  ETC.— Imbed  the  subject  in  a  mould  made 
of  four  parts  of  plaster  of  Paris,  one  of  unburnt  lime  powder,  and 
one  of  Flanders  brick-dust.  Dry  the  mould  carefully,  then  make 
it  red  hot,  and  burn  the  subject  out  of  it,  taking  care  to  free  the 
mould  from  the  ashes.  Fusible  metal  may  be  cast  in  this  mould, 
and  then  be  covered  with  copper,  from  which  the  alloy  may  be 
afterwards  melted,  or  a  wax  model  may  be  taken  of  the  object, 


ELECTROTYPE   PROCESSES.  543 

pouring  the  wax  in  just  bofore  setting.  In  neither  case  must  the 
mould  be  melted  until  after  the  model,  whether  of  alloy  or  wax, 
is  taken,  when  the  whole  is  placed  in  watjr,  the  lime  causes  the 
mould  to  dissolve  or  break  up,  and  the  figure  modelled  within  it 
Viay  be  taken  and  covered  with  copper.  Flowers,  insects,  lizards, 
and  other  little  animals  may  be  typed  in  this  way.  In  all  these 
processes,  perseverance  and  care  are  the  best  cures  for  little 
difficulties. 

WAX  MOULDS  FROM  PLASTER. — If  the  object,  which  we  assume 
to  be  a  medal,  from  which  the  mould  is  to  be  taken,  be  composed 
of  plaster  of  Paris,  and  the  mould  to  be  taken  is  in  wax,  the  first 
operation  is  to  prepare  the  plaster  medal.  Some  boiled  linseed- 
oil,  such  as  is  used  by  house  painters,  is  to  be  laid  over  the  sur- 
face of  the  medal  with  a  camel's  hair  pencil,  and  continued  until  it 
is  perfectly  saturated,  which  is  known  by  the  plaster  ceasing  to  ab- 
sorb any  more  of  the  oil.  This  operation  succeeds  best  when  the 
medal  is  heated  a  little.  The  medal  should  now  be  laid  aside  till 
the  oil  completely  dries,  when  the  plaster  will  be  found  to  be  quite 
hard,  and  having  the  appearance  of  polished  marble ;  it  is,  conse- 
quently, fit  to  be  used  for  taking  the  wax  mould,  which  is  done  in 
the  same  manner  as  we  have  described  for  taking  a  wax  mould 
from  a  metallic  medal. 

Many  prefer  saturating  the  medal  with  water :  this  is  best  done 
by  placing  the  medal  back  down  in  the  water,  but  not  allowing  it 
to  flow  over  the  face ;  the  water  rises,  by  capillary  attraction,  to 
the  surface  of  the  medal,  rendering  the  face  damp  without  being 
wet.  The  rim  being  now  tied  on  the  plaster  medal,  the  melted 
wax  is  poured  upon  it.  This  method  is  equally  good,  but  liability 
to  failures  is  much  greater,  caused  generally  by  the  wax  being 
too  hot. 

The  plaster  medal  may  also  be  saturated  with  skimmed  milk 
and  then  dried ;  by  repeating  this  twice,  the  plaster  assumes  on  the 
surface  an  appearance  like  marble,  and  may  be  used  for  taking 
wax  moulds. 

MOULD  OF  PLASTER  FROM  PLASTER  MODELS. — When  a  plaster 
mould  is  to  be  taken,  the  face  of  the  model  is  prepared  differently 
to  that  described,  in  order  to  prevent  the  adhesion  of  the  two 
plasters.  The  best  substance  we  have  tried  for  this  purpose  is  a 
mixture  of  soft  soap  and  tallow,  universally  used  by  potters  for 
preparing  their  moulds,  and  called  by  them  lacquer.  It  is  pre- 
pared in  the  following  manner : — half-a-pound  of  soft  soap  is  put 
into  three  pints  of  clean  water,  which  are  set  OB  a  clear  fire,  iiml 
kept  in  agitation  by  stirring  ;  when  the  mixture  begins  to  boil,  add 
from  one  ounce  to  an  ounce  and  a-half  of  tallow,  and  keep  boiling 
till  it  is  reduced  in  bulk  to  about  two  pints,  when  it  is  ready  for 
use.  The  surface  of  the  medal  must  be  washed  over  with  this 
lacquer,  allowing  it  to  absorb  as  much  as  it  can,  when  it  assumes 
the  appearance  of  polished  marble  ;  it  is  now  prepared  with  a  rim 
of  paper,  and  the  mould  taken  as  directed  for  taking  plaster 


544  THE   PRACTICAL   METAL-WOEKER?S   ASSISTANT. 

moulds  from  metallic  medals.  When  hardened,  they  will  separate 
easily. — Wetting  the  plaster  model  with  a  solution  of  soap  before 
taking  the  cast  will  do,  or,  if  the  plaster  model  has  been  saturated 
with  oil  or  milk,  it  has  only  to  be  moistened  with  sweet  oil  the 
same  as  a  metal  model. 

FUSIBLE  ALLOY  FROM  PLASTER. — If  a  mould  of  fusible  metal 
be  required  from  a  plaster  medal,  the  plaster  may  be  saturated 
either  with  boiling  oil  or  the  soap  and  tallow  lacquer,  and  the 
mould  taken  in  the  same  manner  as  from  a  metallic  medal. 

COPPER  MOULDS  FROM  PLASTER. — Many  electro-metallurgists 
prefer  taking  a  mould  in  copper  when  the  medal  is  of  plaster  of 
Paris.  This  is  done  by  the  electrotype  process ;  the  plaster  model 
is  saturated  with  wax  over  a  slow  fire,  as  already  detailed,  and  then 
prepared  for  taking  an  electrotype  in  the  usual  manner  (see  page 
534).  We  need  hardly  mention  that  the  model  in  this  case  is  de- 
stroyed ;  but,  notwithstanding,  in  the  case  of  plaster  models,  to 
take  a  copper  mould  is  the  most  preferable,  as  it  may  be  repaired 
in  case  of  slight  defect?,  and  it  may  be  used  over  and  over  again 
without  deterioration. 

When  an  electrotype  is  required  of  a  model  that  is  undercut,  or 
of  a  bust  or  figure,  the  process  which  we  have  described  will  not 
answer,  as  the  mould  cannot  separate  from  the  model.  In  such 
circumstances  the  general  method  of  proceeding  is  to  part  the 
mould  in  separate  pieces,  and  then  join  these  together.  The 
material  used  for  this  purpose  is  plaster  of  Paris.  The  operation, 
however,  to  be  well  done,  requires  a  person  of  considerable  ex- 
perience. 

ELASTIC  MOULDING. — The  process  patented  by  Mr.  Parks  for 
taking  a  mould  of  any  kind  of  model  in  one  piece,  is  excellently 
adapted  for  the  electrotypist.  The  material  is  composed  of  glue 
and  treacle.  Twelve  pounds  of  glue  is  steeped  for  several  hours 
in  as  much  water  as  will  moisten  it  thoroughly ;  this  is  put  into  a 
metallic  vessel,  which  is  placed  in  boiling  water  as  a  hot  bath. 
When  the  glue  falls  into  a  fluid  state,  three  pounds  of  treacle  are 
added,  and  the  whole  is  well  mixed  by  stirring.  Suppose,  now, 
that  the  mould  of  a  small  bust  is  wanted,  a  cylindrical  vessel  is 
chosen  so  deep  that  the  bust  may  stand  in  it  an  inch  or  so  under 
the  edge.  The  inside  of  this  vessel  is  oiled,  a  piece  of  stout  paper 
is  pasted  on  the  bottom  of  the  bust  to  prevent  the  fluid  mixture 
from  going  inside,  and  if  it  is  composed  of  plaster,  sand  is  put  in- 
side to  prevent  it  from  swimming.  It  is  next  completely  drenched 
in_  oil  and  placed  upright  in  the  vessel.  This  done,  the  melted 
mixture  of  glue  and  treacle  is  poured  in  till  the  bust  is  covered  to 
the  depth  of  an  inch.  The  whole  must  stand  for  at  least  twenty- 
four  hours,  till  it  is  perfectly  cool  throughout — after  which  it  is 
taken  out  by  inverting  the  vessel  upon  a  table,  when,  of  course, 
the  bottom  of  the  bust  is  presented  bare.  The  mould  is  now  cut 
by  means  of  a  sharp  knife,  from  the  bottom  up  the  back  of  the 
bust  to  the  front  of  the  head.  It  is  next  held  open  by  the  opera- 


ELECTROTYPE  PROCESSES.  54:5 

tor,  when  an  assistant  lifts  out  tbe  bust  and  the  mould  is  allowed 
to  reclose.  A  piece  of  brown  paper  is  tied  round  it  to  keep  it 
firm.  The  operator  has  now  a  complete  mould  of  the  bust  in  one 
piece ;  but  he  cannot  treat  it  like  wax  moulds,  as  its  substance  is 
soluble  in  water,  and  would  be  destroyed  if  put  into  the  solution. 
A  mixture  of  wax  and  rosin,  with  occasionally  a  little  suet,  is 
melted  and  allowed  to  stand  till  it  is  on  the  point  of  setting,  when 
it  is  poured  carefully  into  the  mould  and  left  to  cool.  The  mould 
is  then  untied  and  opened  up  as  before  ;  the  wax  bust  is  taken  out ; 
and  the  mould  may  be  tied  up  for  other  casts.  Besides  wax  and  rosin 
there  are  several  other  mixtures  used — deer's  fat  is  preferable  to 
common  suet,  stearine,  etc.  The  object  is  to  get  a  mixture  that 
takes  a  good  cast,  and  becomes  solid  at  a  heat  less  than  that  which 
would  melt  the  mould. 

MOULDING  OF  FIGURES. — If  the  model  or  figure  be  composed 
of  plaster  of  Paris,  a  mould  is  often  taken  in  copper  by  deposition. 
The  figure  is  saturated  with  wax,  as  described  for  a  medal,  and 
copper  deposited  upon  it  sufficiently  thick  to  bear  handling  with- 
out damage  when  taken  from  the  model.  The  figure  with  the 
copper  deposit  is  carefully  sawn  in  two,  and  then  boiled  in  water, 
by  which  the  plaster  is  softened  and  easily  separated  from  the  cop- 
per, which  now  serves  as  the  mould  in  which  the  deposit  is  to  be 
made.  It  is  prepared  in  the  same  way  as  we  have  described  for 
depositing  in  copper  moulds.  When  the  deposit  is  made  suffi- 
ciently thick,  the  copper  mould  is  peeled  off  and  the  two  halves  of 
the  figure  soldered  together.  The  copper  moulds  which  are  de- 
posited upon  the  wax  models  taken  in  the  elastic  moulding  are 
often  treated  in  the  same  manner;  but  more  generally  these  moulds 
are  used  for  depositing  silver  or  gold  into  them,  to  obtain  fac- 
similes of  the  object  in  these  metals,  in  which  case  the  copper 
moulds  are  dissolved  off  by  acids,  as  will  be  described  in  a  subse- 
quent section. 

FIGURES  COVERED  WITH  COPPER. — When  plaster  busts  or  figures 
are  wanted  in  copper,  the  most  usual  way  is  to  prepare  the  figure 
with  wax  as  described,  and  to  coat  it  over  with  a  thin  deposit  of 
copper,  letting  the  copper  remain.  Some  operators,  when  it  can 
be  done,  remove  the  plaster  and  wash  over  the  inside  with  an  alloy 
of  tin  and  lead  melted.  In  this  case  the  copper  must  previously  be 
cleaned  by  washing  first  in  a  solution  of  potash,  and  then  with 
chloride  of  zinc.  The  latter  mode  will  cause  the  alloy  to  adhere 
to  the  copper  and  give  it  strength.  In  either  of  these  cases  the 
deposit  must  not  be  very  thick,  or  it  will  throw  the  figures  out 
of  proportion,  such  as  the  features  of  a  bust,  etc.  Any  slight 
roughness  of  deposit  may  be  easily  smoothed  down  by  means  of 
fine  emery. 

THE  PREPARATION  OF  NON-METALLIC  MOULDS  TO  RECEIVE 

DEPOSIT. — Having  detailed  what  we  have  found  best  for  obtaining 

moulds  of  objects  for  the  purpose  of  electrotyping,  we  proceed  to 

the  manner  of  obtaining  a  deposit  upon  these  moulds.     Were  any 

35 


546  THE   PRACTICAL   METAL-WORKER  S   ASSISTANT. 

of  the  plaster  or  wax  moulds  attached  to  the  zinc  and  immersed  in 
the  copper  solution  in  the  same  manner  as  described  with  the 
penny-piece  (page  534),  no  deposit  would  be  obtained,  because 
neither  the  plaster  nor  the  wax  is  a  conductor  of  electricity.  Some 
substance  must  now  be  applied  to  the  surface  in  order  to  give  it 
conducting  power.  There  are  several  ways  of  communicating  this 
property,  but  the  best  and  most  simple  for  the  articles  under  con- 
sideration is  to  apply  common  black  lead  (already  referred  to)  in 
the  following  manner : — A  copper  wire  is  put  round  the  edge  of 
the  medal,  or,  if  wax  moulds  are  used,  a  thin  slip  of  copper  may 
be  inserted  into  the  edge  of  the  mould — or,  being  slightly  heated 
and  laid  upon  the  back,  the  two  will  adhere.  A  fine  brush  is  now 
taken  (we  have  found  a  small  hat-brush  very  suitable)  and  dipped 
into  fine  black  lead,  and  brushed  over  the  surface  of  the  medal. 
The  brushing  is  to  be  continued  until  all  the  face  round  to  the  wire 
upon  the  edge,  or  slip  of  copper  forming  connection,  has  a  com- 
plete metallic  lustre.  A  bright  polish  is  necessary  to  the  obtain- 
ing a  quick  and  good  deposit. 

In  brushing  on  the  black  lead,  care  should  be  taken  not  to  allow 
any  to  go  upon  the  back  or  beyond  the  copper  connection,  or  the 
deposit  will  follow  it,  and  so  cause  a  loss  of  copper,  and  make  the 
mould  more  difficult  to  separate  from  the  deposit ;  being,  as  it 
were,  incased.  If  the  electrotypist  takes  the  labor  himself  of  filing 
off'  all  the  superfluous  copper  from  the  edge  of  his  deposited  medal, 
it  will  do  more  than  any  written  precautions  to  teach  the  necessity 
of  preventing  as  much  as  possible  the  deposit  going  farther  than 
is  necessary.  When  the  face  of  the  mould  is  properly  black- 
leaded,  the  copper  wire  connected  with  it  is  attached  to  the  zinc 
plate  in  the  porous  cell,  and  the  mould  immersed  in  the  copper 
solution ;  the  deposit  will  immediately  begin  upon  the  copper  con- 
nection, and  will  soon  spread  over  every  part,  covering  the  black- 
lead  polish  with  less  or  more  facility  according  to  the  state  of  the 
solutions  and  other  circumstances  to  be  afterwards  noticed.  When 
the  deposit  is  considered  sufficiently  thick  for  removing — which, 
in  ordinary  circumstances,  will  require  from  two  to  three  days — 
the  medal  is  taken  out  of  the  solution,  and  washed  in  cold  water, 
and  the  connection  is  taken  off.  If  the  deposit  has  not  gone  far 
over  the  edge  of  the  mould,  the  two  may  be  separated  by  a  gentle 
pull ;  if  otherwise,  the  superfluous  deposit  must  be  eased  off,  and 
if  care  be  taken  the  wax  may  be  fit  to  use  over  again  :  but  when 
the  mould  is  plaster  of  Paris,  however  well  it  may  be  saturated 
with  wax,  it  is  seldom  in  a  condition  to  use  again.  If  the  plaster 
mould  be  large  and  thick,  it  is  advisable  to  coat  the  back  with  wax 
or  tallow,  which  is  done  by  brushing  it  over  with  either  substance 
in  a  melted  state :  the  mould  being  cold  will  not  absorb  the  wax 
or  tallow:  hence  it  may  be  recovered  again.  The  sulphate  of 
copper  possesses  so  penetrating  a  quality  that  if  the  slightest  im- 
perfection occurs  in  the  saturation  of  the  mould  by  wax,  the  solu  • 
tion  will  penetrate  through  it,  and  the  copper  will  be  deposited 


"?  ELECTROTYPE   PROCESSES.  547 

upon  the  face  of  the  object  adhering  to  the  plaster,  giving  to  the 
metal  a  rough,  matted  appearance,  and  seriously  injuring  it. 

USING  METAL  MOULDS. — The  mould  in  fusible  alloy  does  not 
require  to  be  black-leaded,  but  the  back  and  edge  must  be  pro- 
tected by  a  coating  of  wax  or  other  non-conducting  material ;  it 
may  be  connected  in  the  same  way  as  the  penny-piece  (page  534) 
by  putting  a  wire  round  its  edge  previous  to  laying  on  the  non- 
conducting substance,  such  as  tallow  or  wax,  which  should  also 
cover  the  wire.  Or  a  slip  of  copper,  or  wire,  may  be  laid  upon 
the  back  and  fastened  by  a  drop  or  two  of  sealing- wax ;  the  back 
is  then  coated :  but  care  must  be  taken  that  the  wax  do  not  get 
between  the  connection  and  the  medal  which  will  prevent  deposit. 
The  deposit  on  this  mould  goes  on  instantaneously,  the  same  as 
over  the  penny-piece.  When  sufficiently  thick,  it  may  be  taken 
off  in  the  same  manner  as  from  the  wax  mould,  the  surface  having 
been  prepared  by  turpentine  (page  534)  to  prevent  adherence. 
These  moulds  may  be  used  several  times,  if  care  be  taken  not  to 
heat  them,  as  they  easily  melt. 

The  medals  obtained  from  metallic  moulds  prepared  with  the 
turpentine  solution  have  a  bright  surface,  which  is  not  liable  to 
change  easily,  but  if  the  mould  has  been  prepared  with  oil  or  com- 
posed of  wax  or  plaster,  the  metal  will  either  be  dark,  or  will  very 
easily  tarnish.  The  means  of  preserving  them,  either  by  bronzing 
or  plating  with  other  metals,  will  be  detailed  in  a  subsequent  section. 

PRECAUTIONS  ON  PUTTING  THE  MOULDS  INTO  A  SOLUTION.— In 
putting  moulds  into  the  copper  solution,  the  operator  is  often  an- 
noyed by  small  globules  of  air  adhering  to  the  surface,  which 
either  prevent  the  deposit  taking  place  upon  these  parts,  or,  when 
they  are  very  minute,  permit  the  deposit  to  grow  over  them — 
causing  small  hollows  in  the  mould,  which  give  a  very  ugly  ap- 
pearance to  the  face  of  the  medal.  To  obviate  this,  give  the  mould, 
when  newly  put  into  the  solution,  two  or  three  shakes,  or  give  the 
wire  attached  to  it,  while  the  mould  is  in  the  solution,  a  smart  tap 
with  a  key  or  knife,  or  any  thing  convenient ;  but  the  most  cer- 
tain means  we  have  tried,  is  to  moisten  the  surface  with  alcohol 
just  previous  to  putting  it  into  the  copper  solution.  A  little  prac- 
tice in  these  manipulations  will  soon  enable  the  student  to  avoid 
these  annoyances. 

DEPOSITION  ON  LARGE  OBJECTS. — When  busts  or  figures, 
whether'  of  wax  or  plaster  of  Paris,  are  to  be  coated  with  copper, 
with  no  other  conducting  surface  than  black  lead,  it  is  attended 
with  considerable  difficulty  to  the  inexperienced  electrotypist.  The 
deposit  grows  over  all  the  prominent  parts,  leaving  hollow  places, 
such  as  armpits,  neck,  etc.,  without  any  deposit ;  and  when  once 
missed,  it  requires  considerable  management  to  get  these  parts 
coated,  as  the  coated  parts  give  a  sufficient  passage  for  the  current 
of  electricity.  It  is  recommended  by  some  electrotypists  to  take 
out  the  bust,  and  coat  the  parts  deposited  upon  with  wax,  to  pre- 
vent any  further  deposit  on  them ;  but  this  practice  is  not  good, 


548  THE  PEACTICAL  METAL-WORKER'S  ASSISTANT. 

especially  with  plaster  of  Paris,  for  an  electrotype  ought  never  to 
be  taken  out  till  finished.  Sometimes  the  resistance  of  the  hollow 
parts  is  occasioned  by  the  solution  becoming  exhausted  from  its 
position  in  regard  to  the  positive  pole.  In  this  case  a  change  of 
position  effects  a  remedy.  It  may  be  remarked  that  when  a  bust 
or  any  large  surface  having  hollow  parts  upon  it,  is  to  be  electro- 
typed,  as  many  copper  connections  as  possible  ought  to  be  made 
between  these  parts  and  the  zinc  of  the  battery.  Let  the  connec- 
tions with  the  hollow  parts  be  made  with  the  finest  wire  which  can 
be  had,  and  let  the  zinc  plate  in  the  cell  have  a  large  surface  com- 
pared to  the  surface  of  the  figure,  and  the  battery  be  of  considera- 
ble intensity;  if  attention 'is  paid  to  these  conditions,  the  most  in- 
tricate figures  and  busts  may  be  covered  over  in  a  few  hours.  Care 
has  to  be  observed  in  taking  off  the  connections  from  the  deposit, 
or  the  operator  may  tear  off  a  portion  of  the  deposit :  if  the  wires 
used  are  fine,  they  should  be  cut  off  close  to  the  deposited  surface. 

To  MAKE  BUSTS  AND  FIGURES. — Busts  and  figures,  and  other 
complicated  works  of  art,  which  cannot  be  perfectly  coated  with 
black  lead,  may  be  covered  by  a  film  of  silver  or  gold,  which 
serves  as  a  conducting  medium  to  the  copper.  This  is  effected  by 
a  solution  of  phosphorus  in  sulphuret  of  carbon.  The  operation 
being  patented,  we  will  take  advantage  of  the  description  given  of 
it  in  the  specification.  "  The  solution  of  phosphorus  is  prepared 
by  adding  to  each  pound  of  that  substance  15  Ibs.  of  the  bisul- 
phuret  or  other  sulphuret  of  carbon,  and  then  thoroughly  agitating 
the  mixture;  this  solution  is  applicable  to  various  uses,  and 
amongst  others,  to  obtaining  deposits  of  metal  upon  non-metallic 
substances,  either  by  combining  it  with  the  substances  on  which  it 
is  to  be  deposited,  as  in  the  case  of  wax,  or  by  coating  the  surface 
thereof.  Any  of  the  known  preparations  of  wax,  may  be  treated 
in  this  way,  but  the  one  preferred  is  composed  of  from  6  to  8 
ounces  of  the  solution :  5  Ibs.  of  wax,  and  5  Ibs.  of  deer's  fat, 
melted  together  at  a  low  heat,  on  account  of  the  inflammable  na- 
ture of  the  phosphorus.  The  article  formed  by  this  composition 
is  acted  upon  by  a  solution  of  silver  or  gold  in  the  manner  here- 
inafter described  with  respect  to  articles  which  have  been  coated 
with  the  solution."* 

COATING  OF  FLOWERS,  ETC. — "  If  the  solution  is  to  be  applied 
to  the  surface  of  the  article,  an  addition  is  made  to  it  of  one  pound 
of  wax  or  tallow,  one  pint  of  spirits  of  turpentine,  and  two  ounces 
of  India  rubber,  dissolved  with  one  pound  of  asphalt,  in  bisul- 
phuret  of  carbon,  for  every  pound  of  phosphorus  contained  in 
the  solution.  The  wax  and  tallow  being  first  melted,  the  solution 
of  India  rubber  and  asphalt  is  stirred  in ;  then  the  turpentine,  and 
after  that  the  solution  of  phosphorus  is  added.  The  solution  pre- 
pared in  this  manner  is  applied  to  the  surfaces  of  non-metallic 
substances,  such  as  wood,  flowers,  etc.,  by  immersion  or  brushing  ; 

*  Repertory  of  Patent  Inventions,  1844. 


ELECTROTYPE   PROCESSES.  549 

the  article  is  then  immersed  in  a  dilute  solution  of  nitrate  of  silver, 
or  chloride  of  gold ;  in  a  few  minutes  the  surface  is  covered  with 
a  fine  film  of  metal,  sufficient  to  insure  a  deposit  of  any  required 
thickness  on  the  article  being  connected  with  any  of  the  electrical 
apparatus  at  present  employed  for  coating  articles  with  metal.  The 
solution  intended  to  be  used  is  prepared  by  dissolving  four  ounces 
of  silver  in  nitric  acid,  and  afterwards  diluting  the  same  with 
twelve  gallons  of  water ;  the  gold  solution  is  formed  by  dissolving 
one  ounce  of  gold  in  nitro-muriatic  acid,  and  then  diluting  it  with 
ten  gallons  of  water." 

We  have  frequently  repeated  the  operations  described  by  this 
patentee  with  entire  satisfaction,  and  were  enabled  to  cover  every 
variety  of  surface  with  great  facility. 

The  solutions  of  silver  and  gold,  prepared  as  above,  will  last  for 
a  long  time,  and  do  a  great  many  articles.  When  it  is  convenient 
it  is  best  to  use  both  solutions.  The  connecting  wire  should  first 
be  attached  to  the  article  to  be  coated,  before  being  dipped  into 
the  phosphorus  solution,  but  connected  at  such  parts  as  will  not 
hurt  the  appearance  of  the  object  by  leaving  a  mark  when  it  is 
taken  off.  Care  should  be  taken  not  to  touch  the  article  with  the 
hands  after  it  is  dipped  into  the  solution.  The  object  supported 
by  the  connections  is  immersed  in  the  phosphorus  solution,  where 
it  remains  for  two  or  three  minutes.  When  taken  out  it  is  dipped 
into  the  silver  solution,  and  as  soon  as  the  surface  becomes  black, 
having  the  appearance  of  a  piece  of  black  china,  it  is  to  be  dipped 
several  times  in  distilled  water,  and  then  immersed  in  the  solution 
of  protochloride  of  gold  about  three  minutes :  the  surface  takes  a 
bronze  tinge  by  the  reduction  of  the  gold.  It  is  next  washed  in 
distilled  water  by  merely  dipping,  not  by  throwing  water  upon  it. 
The  wire  connection  is  now  attached  to  the  zinc  of  the  battery, 
and  then  the  article  put  into  the  copper  solution,  and  in  a  few 
minutes  the  article  is  coated  over  with  a  deposit  of  copper.  A 
thin  copper  surface  may  thus  be  given  to  small  busts  or  figures 
without  sensibly  distorting  the  features  by  want  of  proportion. 

FIGURES  FROM  ELASTIC  MOULDS. — When  taking  a  wax  cast 
from  the  elastic  mould,  described  in  page  544,  we  prefer  the  phos- 
phorized  mixture.  After  taking  out  the  mould  it  is  only  neces- 
sary to  make  the  connections,  and  pass  it  through  the  gold  and 
silver  solutions,  as  described,  and  then  to  connect  it  with  the 
battery. 

Wre  may  also  mention  that  the  principal  object  of  making  cop- 
per moulds  by  this  process,  in  the  manufactory,  is  not  to  make  fac- 
similes in  copper,  but  to  make  articles  of  solid  silver  or  gold. 
Copies  of  highly  wrought  work,  either  chased  or  engraved,  or  of 
articles,  duplicates  of  which  cannot  be  obtained,  or  qf  which  the 
workmanship  is  costly,  may  by  this  means  be  made  in  solid  silver 
or  gold,  at  little  more  expense  than  the,  cost  of  the  metal.  Having 
obtained  the  copper  mould,  silver  is  deposited  in  it  to  any  thick- 
ness, and  the  copper  dissolved  off.  However,  an  extensive  trade 


550  THE   PEACTICAL   METAL- WORKER*;*  ASSISTANT. 

is  now  being  carried  on  in  figures  and  other  works  of  art  deposited 
in  copper  and  then  bronzed,  which  gives  them  an  appearance  often 
not  much  inferior  to  that  of  antique  works  of  the  highest  art. 

ELECTROTYPES  FROM  DAGUERREOTYPES. — What  may  be  justly 
termed  the  perfection  of  electrotyping,  is  the  production  of  elec- 
trotypes from  daguerreotypes.  The  daguerreotype  picture  being 
taken,  a  small  portion  of  the  back  is  cleaned  with  sand-paper,  taking 
care  not  to  allow  any  thing  to  touch  the  face  ;  a  little  fine  solder  is 
placed  on  this  part ;  a  piece  of  flattened  wire,  also  cleaned,  is 
placed  upon  the  solder,  the  whole  moistened  with  dilute  muriatic 
acid,  or  chloride  of  zinc.  The  wire  is  now  held  over  the  gas  or  a 
lamp  about  half  an  inch  from  the  plate ;  the  heat  is  transmitted 
through  the  wire  to  the  solder,  which  melts,  and  the  wire  is  sold- 
ered to  the  type ;  the  back  is  then  protected  by  wax,  and  the 
daguerreotype  is  now  put  into  the  copper  solution  in  the  same  man- 
ner as  a  medal ;  the  deposit  proceeds  rapidly,  and  when  sufficiently 
thick  the  two  easily  separate,  and  an  impression  of  the  picture  is 
obtained  from  the  daguerreotype  with  an  expression  softer  and 
finer  than  the  original ;  several  electrotypes  may,  with  care,  be 
taken  from  one  picture.  The  electrotype  may  now  be  passed 
through  a  weak  solution  of  cyanide  of  gold  and  potassium,  in  con- 
nection with  a  small  battery,  and  thus  a  beautiful  golden  tint  be 
given  to  the  picture,  which  serves  to  protect  it  from  the  action  of 
the  atmosphere;  but  they  should  also  be  protected  by  a  glass, 
which  may  be  fixed  on  in  the  manner  pointed  out  in  another  sec- 
tion. The  most  successful  operators  that  we  have  known  in  this 
and  every  other  department  of  electrotyping  are  Dr.  Thomas 
Paterson,  of  Glasgow,  and  Mr.  Bawtree,  of  London. 

DEPOSITING  BY  SEPARATE  BATTERY. — Having  described,  so  far 
as  we  know  them,  the  best  and  most  simple  means  of  obtaining 
moulds,  and  their  preparation  for  receiving  the  deposit  of  the 
metal,  we  return  again  to  the  management  of  solutions  and  bat- 
teries, and  the  application  to  other  metals  besides  copper. 

Although  in  our  account  of  the  porous  or  single  cell  system 
(page  533)  we  have  recommended  it  as  the  best  and  most  economi- 
cal for  electrotyping,  still  many  eminent  electro-metallurgists  prefer 
using  the  battery  system ;  and  indeed  there  are  solutions  of  copper 
and  of  other  metals  to  which  the  porous  cell  system  cannot  be  ap- 
plied, from  the  nature  of  the  solution  and  the  necessity  of  intensity 
to  decompose  them. 

While  depositing  upon  a  mould  by  the  single  cell,  let  the  wire 
which  connects  them  be  cut  in  the  middle,  and  a  mould  be  attached 
to  the  end  of  the  portion  remaining  upon  the  zinc  plate,  and  a 
small  plate  of  copper  to  the  end  of  the  wire  remaining  upon  the 
mould  in  the  copper  solution,  and  let  these  two  be  put  into  a  second 
vessel  containing  a  solution  of  sulphate  of  copper.  The  action 
between  the  zinc  and  medal  in  the  double  or  first  cell  will  go  on 
as  before— namely,  the  electricity  passing  through  the  porous  cell 
and  the  solution  to  the  medal ;  but  on  returning  to  the  zinc  it  must 


ELECTROTYPE   PROCESSES. 


551 


pass  through  the  copper  solution,  which  is  in  the  second  vessel, 
between  the  mould  and  copper  plate,  where  it  produces  the  same 
effects  as  in  the  first  cell.  The  sulphuric  acid  is  liberated  at  the 
copper  plate  and  dissolves  it,  and  the  copper  is  deposited  upon  the 
mould,  so  that  the  solution  in  this  cell  is  maintained  at  one  strength ; 
hence  there  is  no  necessity  for  hanging  crystals  of  sulphate  of 
copper  in  this  solution. 

It  will  be  observed  that  the  electricity  having  to  pass  through  a 
second  solution,  is  made  to  perform  double  duty,  and  must  conse- 
quently be  much  more  economical.  We  found  the  results  to  be 
these:  A  single  cell,  with  a  mould,  was  placed  two  inches  from  the 
porous  cell,  and  of  the  same  size  as  the  zinc  plate  ;  and  another, 
similarly  arranged,  but  connected  with  a  metal  mould  and  copper 
plate  of  similar  size  to  the  zinc  and  copper,  was  placed  one  inch 
apart  in  the  copper  solution  of  second  cell.  The  mould  in  the 
single  cell  had  gained  100  grains,  and  the  zinc  plate  lost  10$ 
grains.  The  mould  in  the  battery  cell  of  the  other  arrangement 
had  only  deposited  upon  it 
30  grains — the  zinc  plate 
had  lost  35  grains ;  but  the 
mould  in  the  second  or  de- 
composition cell  had  also 
deposited  upon  it  30  grains, 
making  in  all  60  grains  de- 
posited for  35  zinc  dissolved, 
but  taking  nearly  double  the 
time.  These  arrangements, 
as  we  have  before  observed, 
are  simply  a  modification 

of  a  single  pair  of  Dauiell's  battery  connected  with  a  decompo- 
sition cell,  the  advan- 
tages of  which  are  not 
applicable  to  any  other 
battery,  as  in  no  other 
battery  does  deposition 
take  place  within  the 
battery  cells :  indeed  this 
method  of  using  a  com- 
pound depositing  appa- 
ratus is  very  seldom  em- 
ployed. Batteries  of  a 
different  form,  as  Smee's 
are  generally  adopted. 
Figure  573  represents  a 
Smee's  battery,  connected  with  a  medal  and  copper  plate  in  a  sepa- 
rate or  decomposition  cell ;  and  Fig.  574  is  a  large  decomposition 
trough  for  doing  several  medals  at  one  time.  Of  course  any  bat- 
tery may  be  attached  to  these  medals  and  plate  by  the  brass  con- 
nections seen  on  the  end  of  the  trough.  Bear  in  remembrance 


Fig.  574. 


552 


THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 


that  the  zinc  of  the  battery  is  connected  with  the  medals,  and 
the  copper  or  platinized  silver  with  the  copper  in  the  decompo- 
sition cell. 

SIZE  OF  THE  ELECTRODES. — When  a  separate  battery  is  used  for 
the  purpose  of  depositing  in  a  decomposition  cell,  there  are  several 
conditions  which  are  well  to  be  observed,  as  they  influence  the 
amount  and  character  of  the  deposit:  The  first  is  the  size  of  the 
electrodes  or  medals,  in  relation  to  the  zinc  in  the  battery.  The 
results  we  have  obtained  may  be  expressed  in  general  terms. 
When  the  deposit  upon  electrodes  of  the  same  size  as  the  zinc 
plates  in  a  Wollaston's  battery  equals  100,  that  upon  electrodes  one 
half  the  size  of  the  zinc  plates  in  the  battery  will  be  equal  to  57, 
and  upon  electrodes  double  the  size  of  the  zincs  of  the  battery  190 ; 
but  this  last  condition  is  affected  by  the  intensity  of  the  arrange- 
ment. 

EELATIVE  POWER  OF  BATTERIES. — The  following  experiments, 
made  with  electrodes  double  the  size  of  the  zinc  plates  of  the  bat- 
teries, all  at  equal  distances  (1  inch  apart),  will  show  the  relative 
power  of  the  batteries.  The  time  in  action  was  one  hour  each : 
only  one  pair  of  plates  constituted  the  battery. 


Grove's  battery  deposited 

Single  cell 

Tt»«;.nii>. 


104  grains. 
62      " 

Darnell's 33      " 

Smee's 22      " 

Wollaston's .  18      " 


CONSTANCY  OF  BATTERIES. — But  the  first  hour  of  the  action  of 
most  batteries  differs  from  an  hour  afterwards,  so  that  one  kind  of 
battery  may  be  most  useful  for  a  short  time,  and  another  sort  if 
the  action  is  to  be  continued  for  a  length  of  time.  The  following 
table  will  illustrate  this  remark,  the  condition  being  the  same  as  in 
last  experiment,  or  the  last  experiments  being  continued,  and  the 
results  taken  every  hour  for  seven  successive  hours : 


1 

2 

3 

4 

5 

6 

7 

hour. 

hours. 

hours. 

hours. 

hours. 

hours. 

hours. 

Total. 

Grove's  battery  . 
Single  cell  .  .  . 
Daniell's  .  .  . 

104 
62 
33 

86 
57 
35 

66 
54 
34 

60 
46 
32 

54 
39 

3?, 

49 
29 
30 

45 
24 
31 

464  grs. 
311    " 
227   " 

Smee's  .... 

22 

16 

14 

11 

1| 

11 

10 

96   " 

Wollaston's  .  . 

18 

14 

15 

12 

11 

10 

10 

90   " 

To  make  this  comparision  more  practical,  larger  plates  were  used 
for  the  battery,  and  proportionately  larger  electrodes,  and  the  bat- 
tery kept  in  operation  until  one  pound  of  copper  was  deposited, 


ELECTROTYPE    PROCESSES.  553 

renewing  the  acid,  and  brushing  the  zincs  every  24  hours.     The 
time  taken  to  effect  this  was:  f 

Grove's  Battery 19  £  hours. 

Single  cell 45 

Daniell's* 49 

Smee's 147 

Wollaston's 151 

COMPARATIVE  PRODUCE  OP  BATTERIES. — The  expense  of  the 
materials  used  in  these  experiments  was  as  follows  (of  course  the 
materials  will  differ  in  cost  both  at  different  times  and  in  different 
localities,  and  more  common  materials  may  be  used) : 

By  the  process  with  Grove's  battery,  one  pound  of  deposited 
copper  costs  • 

1  Ib.  Copper,  from  positive  electrodes     ...  25  cts. 

1£  Ib.  Amalgamated  zinc 21    " 

ij  Ib.  Nitric  acid 19    " 

Sulphuric  acid 02    " 

67  cts. 
Add  time,  say  one  cent  per  hour,  for  comparison  .     .       20    " 

87  cts. 

By  single  cell  apparatus,  one  pound  of  deposited  copper  costs 

1  Ib.  Sulphuric  acid 04  cts. 

IT'S  Ib.  Amalgamated  zinc    .    .*.<:>.•*£»•.     .  17    " 

4  Ib.  Sulphate  of  copper 37    " 

58  cts. 
Time,  at  one  cent  per  hour  »%u^  «.u*i.!4-it;.*;.-, .    .    .       45    " 


$1.03 

By  Daniell's  battery,  one  pound  of  deposited  copper 

IfV  Ib.  Amalgamated  zinc 

4  Ib.  Sulphate  of  copper       .......       37 

1  Ib.  Copper  from  electrode 25 

Sulphuric  acid     .     .     ......    .       02 


costs 
19  cts. 


83  cts. 
Time,  at  one  cent  per  hour 49    " 

$1.32 


*  The  Daniell's  battery  used  in  this  experiment  had  flat  plates,  not  circular, 
as  described  at  page  523. 


554  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

By  Smee's  battery,  one  pound  of  deposited  copper  costs 

1J  Ib.  Amalgamated  zinc 21  cts. 

3  Ib.  Sulphuric  acid 12    " 

1  Ib.  Copper  from  electrode 25    " 

58  cts. 
Time,  at  one  cent  per  hour •    -  :  •    •  $1-4" 

$2.05 

By  Wollaston's  battery,  one  pound  of  deposited  copper  costs 

1  Ib.  Copper  from  electrode 25  cts. 

1  W  Ib.  Amalgamated  zinc 19    " 

3  Ib.  Sulphuric  acid     ..........        12    " 

55  cts. 
Time,  at  one  cent  per  hour $1.51 

$2.06 

By  thus  adding  the  time,  at  a* given  rate,  it  serves  to  illustrate 
what  we  have  before  stated  respecting  the  necessity  of  placing  the 
value  of  time  against  the  cost  of  materials.  In  manufactories, 
where  time  has  to  be  paid  for,  it  may  be  cheapest  to  use  the  bat- 
tery with  the  most  costly  materials ;  but  where  time  is  of  no  con- 
sideration, or,  as  is  often  the  case,  if,  while  the  operations  are  going 
on,  the  workmen^  are  employed  in  other  necessary  labor,  a  cheaper 
apparatus  will  answer:  but  the  student  or  manufacturer  will,  by  the 
above  general  results,  be  enabled  to  choose  the  process  most  suit- 
able for  his  purposes.  It  must  be  borne  in  mind  that  an  allowance 
has  to  be  made  on  the  first,  second,  and  third,  for  wear  and  tear  of 
the  porous  vessels,  not  included  in  the  above  estimate.  Although 
the  results  of  these  experiments  give,  exclusive  of  time,  the  cost  of 
one  pound  of  electrotyped  copper — thus 

Grove's  battery     ...  67  cts. 

Single  cell 58   " 

Daniell's  ......  83    " 

Smee's 58   " 

Wollaston's 55   " 

still  we  know  from  long  experience  in  the  use  of  single  cell,  Smee's, 
and  Wollaston's  batteries,  for  manufacturing  purposes,  that  the 
price  of  the  pound  of  copper  deposited  may  be  more  correctly 
stated  at  62  cents — there  being  always  loss  in  making  the  purest 
article  (the  copper)  from  impure  materials,  as  the  sulphate  of  cop- 
per, or  the 'ordinary  copper  of  commerce  which  is  used  as  elec- 
trodes. 

Mr.  Smee,  in  his  "Advice  to  capitalists  who  propose  entering 


ELECTROTYPE  PROCESSES.  555 

upon  the  business  of  electro-metallurgy,"  gives  a  table  of  expenses 
incurred  by  the  use  of  different  batteries.  But  his  rules  are  based 
too  exclusively  upon  theoretical  considerations,  and  without  that 
regard  for  practical  conditions  which  are  so  important  to  the  manu- 
facturer. Mr.  Smee  recommends  for  use  what  he  calls  "  an  odds- 
and-ends  battery,"  composed  of  odd  scraps  of  zinc  put  into  acid, 
having  in  the  same  vessel  a  piece  of  copper  or  platinized  silver  and 
a  wire  placed  in  contact  with  them  which  forms  the  electrode. 
This  battery  may  be  convenient  for  the  amateur  electrotypist,  as  it 
enables  him  to  use  up  all  his  waste  zinc.  Raw  zinc,  or  spelter,  Mr. 
Smee  says,  may  also  be  used  in  this  way,  constituting  the  cheapest 
of  all  batteries  for  manufacturing  purposes.  The  data  of  his  cal- 
culations are  as  follows : — The  copper  sheet  forming  the  positive 
electrode  is  quoted  at  25  cents  per  Ib. ;  wrought  zinc,  14  cents  per 
Ib. ;  raw  zinc  at  a  little  more  than  half  the  price  of  wrought  zinc, 
which  we  will  call  8  cents  per  Ib.,  although  he  rates  it  at  10  cents. 
Iron  is  given  at  from  2  to  4  cents  per  Ib.  The  equivalent  weight 
of  copper  is  given  at  32,  of  zinc  at  32,  and  of  iron  at  28 ;  that  is 
to  say,  32  parts  (say  ounces)  of  zinc  dissolved  in  a  battery  will,  or 
should  deposit  32  ounces  of  copper;  and  if  iron  be  used,  28  ounces 
of  iron  should  deposit  32  ounces  of  copper.  Hence,  in  the  plain 
language  of  a  manufacturer,  we  should  say  that,  with  an  odds-and- 
ends  battery  and  raw  zinc,  there  would  be,  for  every  pound  of  cop- 
per deposited, 

16  oz.  of  zinc  used  ....     08  cts. 
16  oz.  of  copper  dissolved  .     .     25    " 

33  cts.  f 

And  when  iron  is  used,  the  expense  of  depositing  1  Ib  of  copper 
would  be, 

16  oz.  of  iron,  say    ....    04  cts. 

16  oz.  of  copper  .    .    .    . v  .    25   " 

29  cts. 

Notwithstanding  these  results,  Mr.  Smee  proves,  by  several  frac- 
tional formulae  and  an  algebraic  equation,  that  the  cost  of  deposit- 
ing a  pound  of  copper  is 

By  iron 87  cts. 

By  odds-and-ends  battery  .     .    25    "  * 

62  cts. 

To  this  it  may  be  replied  by  the  manufacturer,  that,  in  the  first 
place,  raw  zinc  or  spelter  used  in  the  way  described  for  an  odds-and- 
ends  battery  would  lose  two  or  three  times  the  quantity  that  is 
stated  for  every  equivalent  of  copper ;  and  secondly,  that  this  form 

*  Smee's  Elements  of  Electro-metallurgy,  3d  edition,  p.  112. 


556  THE   PRACTICAL   METAL  -WORKER'S   ASSISTANT. 

of  battery  is  altogether  unsuitable  for  manufacturing  purposes, 
even  when  amalgamated  scrap  zincs  are  used ;  and,  as  regards  the 
calculation,  it  is  not  easy  to  see  that,  while  a  pound  of  copper,  dis- 
solved from  the  positive  electrode,  originally  costs  25  cents,  it 
could,  notwithstanding,  be  deposited  by  the  destruction  of  1  Ib.  of 
zinc,  not  including  acid,  etc.,  at  the  expense  of  only  25  cents.  It 
ought  always  to  be  remembered,  that,  for  manufacturing  purposes, 
the  surface  upon  which  the  metal  is  to  be  deposited  in  general 
amounts  to  several  square  feet.  The  article  may  be,  for  example,  a 
large  ornamental  vase,  having  four  square  feet  of  surface.  An 
odds-and-ends  battery,  or  an  iron  single  pair  battery  would  be  too 
weak.  To  deposit,  with  a  separate  battery,  upon  a  surface  such  as  that 
of  the  vase,  it  requires  two  or  three  pairs  of  plates  to  give  what  we 
may  call  economical  power. 

KECOVERY  OF  MERCURY  FROM  WASTE  ZINC. — The  general 
practice  of  manufacturers,  when  the  scraps  of  zinc  become  small, 
is  either  to  treat  them  as  referred  to  at  page  512,  to  distil  the  mer- 
cury from  the  zinc,  or  to  sell  the  scraps  to  parties  who  do  distil 
them.  This  is  done  by  putting  the  scraps  into  an  iron  retort,  sub- 
jecting it  to  a  red  heat,  and  allowing  the  beak  of  the  retort  to  pass 
into  a  condenser,  which  has  a  tube  dipping  into  water.  The  mer- 
cury distils  over,  and  condenses  in  the  water.  The  zinc  left  in 
the  retort  is  found  to  be  so  impure  as  not  to  be  fit  to  melt  and  roll 
again,  but  it  may  be  used  in  the  composition  of  common  brass. 
Mr.  De  la  Eue,  in  a  communication  to  the  Chemical  Society,*  gives 
the  results  of  several  analytical  experiments  upon  scrap  zinc.  Be- 
fore distillation  the  scraps  usually  give  the  following  results  in  100 
parts  ^ 

Zinc  .  .-.  .  .  .  67-3 
Mercury  ....  4*3 
Dross  and  loss  .  ,  28'4 


100-0 
The  composition  of  the  zinc  left  after  distillation  is  given  as — 

Zinc 90' 

Iron 2'56 

Lead    .....    6- 
Copper     ....     1-44 

100-00 

COMPOUND  CELL  PROCESS. — Another  method  of  economizing 
power  was  proposed  in  what  is  termed  the  compound  cell  system, 
by  which  it  was  said  that  the  electricity  passing  through  a  series 
of  cells  would  be  able  to  produce  the  same  quantity  of  work  in 
every  cell  with  no  more  cost.  This  plan  may  be  stated  thus : 

A  is  a  Smee's  battery;  the  wire  z  is  conducting  the  electricity  to 

*  Memoirs  and  Proceedings  of  the  Chemical  Society,  vol.  ii.  page  393. 


ELECTROTYPE   PROCESSES. 


557 


the  compound  trough  which  is  composed  of  a  series  of  water-tight 
cells,  as  a  a,  and  is  connected  with  a  piece  of  copper  c,  forming  a 
positive  electrode ;  in  the  same  cell,  and  facing  this  electrode,  is  a 
medal,  connected  by  a  copper  wire  to  a  piece  of  copper  placed  in 
the  second  cell,  opposite  which  is  another  medal  connected  in  the 

Fig.  575. 


same  manner  with  another  piece  of  copper,  and  so  on  through  the 
series,  which  terminates  with  a  medal  attached  to  the  wire  of  the 
battery.  The  electricity  from  the  battery  passes  through  all  these 
cells,  and  reduces  its  equivalent  in  each  cell.  Thus  the  reduction 
.of  32  grains  of  zinc  in  the  battery  would  deposit  32  grains  of 
copper  multiplied  by  6  times,  or  as  many  times  as  there  are  cells. 

This  is  correct  in  principle,  and  at  first  sight  seems  to  be  exceed- 
ingly economical  j  but  it  is  not  so,  for  every  cell  adds  so  much  to 
the  resistance  of  the  current,  that  intensity  batteries  must  be  used ; 
so  that,  supposing  we  have  a  compound  cell  of  six  divisions,  in 
which  are  placed  six  separate  medals,  it  would  require  a  battery 
of  six  pairs  of  plates  to  give  intensity  sufficient  to  overcome  the 
resistance,  and  the  same  number  of  medals  could  be  made  of  the 
same  weight  by  six  separate  zincs,  and  in  less  than  half  the  time 
they  could  be  made  by  this  arrangement,  and  with  a  less  destruc- 
tion of  zinc.  For  large  operations,  where  the  articles  receiving 
the  deposits  and  the  electrode  are  necessarily  a  good  way  apart, 
the  process  is  altogether  impracticable  in  a  commercial  point  of 
view.  This  is  one  of  the  remarkable  instances  where  theoretical 
possibility  and  commercial  economy  are  at  variance. 

EFFECTS  OF  EESISTANCE. — At  page  551  we  mentioned,  that  if  a 
single  cell  deposits  100  grains  in  a  given  time,  and  it  be  converted 
into  a  battery  having  the  two  electrodes  in  a  solution  of  sulphate 
of  copper,  there  will  only  be  deposited  in  the  same  time  30  grains. 
This  is  caused  by  the  extra  resistance  which  the  solution  between 
the  two  electrodes,  in  the  decomposition  cell,  offers  to  the  passage 
of  the  electricity,  the  amount  of  which  corresponds  to  the  amount 
deposited — the  latter  depending  upon  the  former. 

If  we  take  two  small  plates  of  copper  and  zinc  amalgamated, 
and  place  them  in  dilute  sulphuric  acid,  in  contact,  but  not  so  close 
as  to  prevent  the  gas  evolved  from  the  copper  plate  to  escape,  and 
allow  them  to  remain  until  there  have  been  dissolved  from  the  zinc 


558  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

100  grains,  and  we  call  this  the  measure  of  the  maximum  amount 
of  electricity  which  that  surface  of  zinc  and  copper  can  give  out 
in  the  time  taken  to  dissolve  the  100  grains :  then,  if  the  two 
metals  in  the  acid  be  separated  one  inch,  being  connected  by  a 
wire  or  slip  of  copper  above  the  liquid,  and  kept  in  action  the 
same  length  of  time  as  the  former,  there  will  be  dissolved  from  the 
zinc  only  about  56  grains.  .If  the  wire  in  connection  with  the  zinc 
and  copper  be  extended  and  cut  in  the  middle,  and  have  a  piece 
of  copper  attached  to  each  of  the  same  size  as  the  zinc  plate  in 
acid,  and  these  be  placed  in  another  vessel  containing  a  solution 
of  sulphate  of  copper  (as  Fig.  544),  and  put  an  inch  apart,  and 
the  whole  kept  in  action  the  same  length  of  time  as  before,  it  will 
be  found  in  this  case  that  only  10  grains  of  zinc  are  dissolved. 
From  these  experiments  we  see  that  the  resistance  of  the  one 
inch  of  acid  between  the  zinc  and  copper  in  the  battery,  and  the 
one  inch  of  solution  of  sulphate  of  copper  in  the  second  or  de- 
composition cell,  is  90  or  nine-tenths — only  yielding  one-tenth  of 
the  electricity  which  the  zinc  and  copper  are  capable  of  giving. 

INTENSITY. — If  we  now  take  another  zinc  and  copper  plate  of 
the  same  size  as  the  former,  and  arrange  them  in  the  acid  solution, 
and  connect  them  with  the  copper  plates  in  the  decomposition  cell, 

as  shown  in  Fig.  544,  and  keep 

Fi£-  5?6.  them  in  action  the  same  length 

of  time  as  in  the  former  experi- 
ments, there  will  be  dissolved 
from  the  zinc  about  19  grains, 
and  deposited  upon  the  copper 
plate  attached  to  the  zinc  in  the 
decomposition  cell  18  grains  of 
copper. 

„  If  three  zincs  and  coppers  be 

arranged  as  described  and  placed  in  the  acid,  there  will  be  dis- 
solved from  the  zinc  plate  26  grains,  and  deposited  upon  the  copper 
25  grains.  If  six  pairs  zinc  and  copper  be  arranged  as  above  and 
placed  in  acid,  there  will  be  deposited  36  grains  of  copper,  which 
we  will  also  take  as  the  measure  of  what  is  dissolved  from  the  zinc ; 
and  if  nine  pairs  of  zinc  and  copper  be  used,  there  will  be  de- 
posited 43  grains,  and  so  on  until  the  quantity  dissolved  from  each 
zinc,  or  deposited  on  the  copper  plate  be  100,  equal  to  that  ob- 
tained by  the  close  contact  of  the  zinc  and  copper  in  acid,  which 
will  require  up  wards  of  30  pairs  of  zinc  and  copper.  It  must  be 
borne  in  mind  that  the  same  quantity  of  zinc  will  be  dissolved 
from  every  plate  in  the  arrangement.  Thus,  in  nine  pairs  where 
43  grains  were  deposited,  there  would  be  dissolved  from  every  zinc 
in  the  battery  43  grains. 

It  will  now  be  apparent  that  the  use  of  several  pairs  in  the  bat- 
tery is  to  overcome  resistance,  by  which  quantity  is  gained  at  the 
same  time  up  to  a  given  point ;  but  quantity  gained  by  this  means 
is  expensive.  The  10  grains  deposited  by  the  single  pair  of 


ELECTROTYPE  PROCESSES. 


559 


zinc  and  copper  only  required  10  grains  of  zinc,  but  the  43 
grains  by  the  nine  pairs  would  require  405  grains  of  zinc  to  be 
dissolved. 

RELATIVE  INTENSITY  OF  BATTERIES. — Different  batteries  have 
different  degrees  of  power  to  overcome  resistance — greater  in- 
tensity. The  following  experiments  will  illustrate  this  :  A  single 
pair  of  a  "Wollaston's,  Smee's,  and  Grove's  batteries  were  fitted  up 
as  nearly  equal  in  circumstances  as  the  different  arrangements 
would  allow — each  exposing  the  same  surface  of  zinc,  and  con- 
nected with  electrodes  placed  in  a  solution  of  sulphate  of  copper, 
first  1  inch,  then  2  inches,  3  inches,  and  4  inches  apart — half  an 
hour  in  each.  They  were  then  reversed,  beginning  with  the  elec- 
trodes at  4  inches  and  coming  to  1  inch.  These  experiments  were 
repeated  several  times,  and  a  mean  of  the  whole  taken.  The  re- 
sults were : 


Deposited — 

Electrodes  1  inch     . 

2  inches 

3  inches 

4  inches 


Wollaston. 

.  8'8  grains 
.  6-6      " 
.  47      " 
.  3-0      " 


Smee. 

12-0 

6-8 

•   0-0 

4-6 


Grove. 

31-0 
26-0 
17-0 
14-0 


From  this  it  will  be  seen  that  Wollaston's  stands  lowest  in  in- 
tensity, which  is  more  apparent  as  the  distance  of  the  electrodes  is 
increased.  Smee's  is  one-third  more  than  Wollaston's  at  1  inch, 
and  one-half  more  at  4  inches ;  while  Grove's  is  three  and  a-half 
more  than  Wollaston's,  and  two  and  a-half  more  than  Smee's  at 
1  inch,  but  four  and  a-half  more  than  Wollaston's  and  three 
more  than  Smee's  at  4  inches.  If  we  take  the  mean  of  these 
results  as  a  comparison  of  batteries,  their  value  will  stand  as 
under: 

One  of  Grove's  equal  to  three  of  Smee's, 

and  to  three  and  three-fourths  of  Wollaston's. 

The  following  table  gives  the  results  of  different  batteries,  ar- 
ranged in  series,  kept  in  action  the  same  length  of  time,  namely, 
one  hour.  The  battery  plates  were  very  small,  the  electrodes 
twice  the  size  of  the  battery  plates  : 


One 
Pair. 

Two 
Pairs. 

Four 
Pain. 

Six 
Pain. 

Nino 
Pain. 

55 

7? 

93 

97 

98 

Daniell's  

15 

85 

60 

77 

86 

11 

19 

?9 

41 

58 

Wollaston's  

8 

15 

9,4 

33 

48 

»  

560  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT. 

This  table  gives  results  approaching  to  and  in  principle  the  same 
as  the  others:  it  will  be  observed  that  one  pair  of  Grove's  is  equal 
to  nine  pairs  of  either  Wollaston's  or  Smee's.  It  is  also  worthy  of 
remark,  that  Grove's  increases  slowly  in  quantity  above  four  pairs, 
the  intensity  being  sufficient  at  four  pairs  to  overcome  the  resist- 
ance offered  to  the  current  of  electricity.  For  ordinary  electro- 
typing,  intensity  arrangements  are  unnecessary,  except  where  the 
article  upon  which  the  deposit  is  being  made  is  of  such  a  character 
as  will  not  allow  the  positive  electrode  to  be  brought  close  to  it,  or 
when  there  are  deep  cut  objects,  or  any  circumstance  that  increases 
distance  and  necessitates  power  to  overcome  resistance. 

MODE  OF  SUSPENDING  OBJECTS  FOR  COATING. — In  beginning  to 
operate  in  the  art  of  electrotyping,  the  student  often  pauses,  and  asks 
the  question,  "What  is  the  best  position  in  which  a  medal  should  be 
hung  in  the  solution?  Convenience  has  brought  into  general  prac- 
tice the  suspending  of  it  perpendicularly  in  the  solution,  ha.ving  the 
positive  electrode  or  pole  facing  it  in  a  parallel 
577-  direction ;  but  to  this  method  there  are  some 

objections.  If,  for  instance,  the  porous  diaph- 
ragm, or  single-cell  system  be  used,  for  obtain- 
ing the  medals,  it  is  found  that  upon  the  lower 
portion  of  the  medal  the  deposition  is  much 
thicker  than  upon  the  upper  portion.  Indeed, 
when  even  ordinary  attention  is  not  paid,  the 
lower  part  becomes  not  only  thicker,  but  stud- 
ded over  with  round  nodules  of  copper,  or  with  lines  composed  of 
these  nodules,  while  the  upper  part  remains  thin,  and  is  covered  over 
with  what  is  termed  the  sandy  deposit  copper,  in  dark  brown  grains, 
capable  of  being  rubbed  off  with  the  slightest  friction.  No  doubt 
this  is  in  a  great  measure  prevented  by  agitating  the  solution ;  but 
it  is  inconvenient,  and  requires  constant  attention. 

If  a  separate  battery  is  used,  and  the  deposition  of  the  medal  is 
effected  in  a  separate  vessel,  by  having  a  copper  positive  electrode, 
the  same  inconvenience  takes  place  to  a  greater  or  less  extent, 
according  to  the  distance  at  which  the  two  poles  are  placed.  These 
inconveniences  are  known  to  all  electrotypists,  and  the  cause  is 
ascribed  to  the  different  densities  of  the  solution.  The  reason  why 
the  solution  becomes  of  different  densities  is  easily  understood  in 
the  single  cell  process,  there  being  no  copper  pole  to  maintain  the 
strength  of  the  solution ;  as  it  becomes  exhausted  of  copper  by  the 
deposition,  the  lighter  portion  floats  on  the  top,  and  the  heavier 
portion  remains  below;  and  although  crystals  of  sulphate  of  cop- 
per be  suspended  in  the  solution,  as  they  dissolve  they  sink  by  their 
gravity,  and  cause  a  flow  upon  the  lower  portion  of  the  medal,  and 
consequently  a  much  more  powerful  deposit.  But  why  the  same 
should  take  place  with  a  separate  battery,  where  there  is  a  posi- 
tive electrode  of  copper  being  dissolved,  just  in  proportion  to  the 
copper  extracted  from  the  solution  by  the  medals,  was  for  a  long 
time  not  known. 


ELECTROTYPE   PROCESSES.  561 

NON-TRANSFER  OF  ELEMENTS. — In  a  paper  read  upon  this  sub- 
ject before  the  Koyal  Society  by  the  late  Professor  Daniell  and 
Professor  Miller,  they  gave,  as  the  results  of  their  investiga- 
tions, that  certain  metals  are  transferred  by  the  electric  current  in 
small  proportion,  differing  in  different  metals.*  About  the  same 
time  the  author  had  observed,  when  operating  upon  the  large  scale, 
results  which  led  him  to  the  conclusion,  that  no  metal  is  trans- 
ferred in  any  quantity  by  the  electric  current,  nor  any  element 
taking  the  position  of  the  metal  in  an  electrotype,  but  that  the 
acid  element  was  always  transferred  equivalent  to  the  electricity 
passing.  It  was  thus  shown  that  during  the  deposition  of  metal, 
say  copper,  in  electrotyping,  the  acid,  when  exhausted  of  the  cop- 
per at  the  surface  of  the  medal,  is  transferred  to  the  positive  pole, 
and  dissolves  a  portion  of  copper ;  but  this  portion  is  not  transferred 
by  the  electric  current  to  the  medal :  hence  it  will  be  observed, 
that  the  solution  next  the  medal  will  become  exhausted  of  cop- 
per, and  will  consequently  rise  to  the  surface  from  its  greater 
lightness.  There  is  no  doubt  a  flow  of  stronger  solution  in  a  hori- 
zontal direction  from  the  positive  pole  to  the  medal,  caused  by  the 
lighter  portion  ascending;  but  this  does  not  mend  the  evil:  the 
light  portion  is  increasing  on  the  surface,  and  the  whole  solution 
soon  becomes  of  different  densities  from  the  surface  to  the  bottom 
of  the  medal ;  and  this  constant  current  of  the 
solution  flowing  up  the  surface  upon  which  the  g' 

electrotypist  is  depositing,  causes  the  lines  that 
are  observed  in  deposits  under  certain  circum- 
stances, and  which  are  sometimes  very  annoy- 
ing. If  a  small  hollow  be  in  the  mould,  or 
even  if  a  small  portion  of  a  plain  surface  resist, 
the  metal  will  accumulate  round  the  edge  of 
the  resisting  portion,  giving  the  deposit  an  ap- 
pearance as  if  made  in  a  flowing  stream,  like  a 
stone  standing  up  in  a  current  of  water.  The  black  point  in  tho 
centre  represents  the  resisting  spot  around  which  the  deposit  will 
thicken,  causing  a  ridge  of  metal  to  radiate  to  a  point  immediately 
above  the  resisting  portion.  These  disappointments  are  much 
more  annoying  in  solutions  of  gold  and  silver  than  in  sulphate  of 
copper,  as  will  be  noticed  when  we  come  to  treat  of  plating  and 
gilding.  A  point  of  grease  or  dirt,  or  small  hole  not  cleaned  out, 
hardly  visible  to  the  naked  eye,  will  give  a  very  prominent  effect 
upon  the  plain  polished  surface  of  a  piece  of  metal. 

From  these  observations,  the  reader  will  now  be  able  to  answer 
the  question — what  is  the  best  position  to  place  a  medal  in  the 
solution  ?  To  make  it  still  more  apparent,  take  a  glass  jar,  filled 
with  a  solution  of  sulphate  of  copper;  place  a  piece  of  copper 
upon  the  bottom  of  the  jar,  and  suspend  the  medal  at  the  top, 

*  Philosophical  Transactions,  Parti,  for  1844;  and  Memoirs  and  Proceeding* 
of  the  Chemical  Society,  Vol.  iii.  page  53. 

36 


562  THE    PRACTICAL    METAL-WORKER'S   ASSISTANT. 

having  their  two  faces  parallel ;  connect  them  with  a  battery  ;  in 
a  short  time  the  solution  round  the  medal  becomes  exhausted,  and 
even  colorless,  the  medal  covered  with  a  dirty  brown  powder,  and 
no  further  deposit  will  take  place.  But  reverse  the  case ;  place 
the  medal  at  the  bottom,  and  the  copper  positive  electrode  at  the 
top ;  the  deposition  goes  on  constant  and  smooth ;  the  solution  is 
maintained  in  the  same  condition  as  it  was  at  the  first,  there  being 
a  constant  transfer ;  the  acid  is  transferred  by  the  current  from  the 
medal  to  the  copper  pole :  the  sulphate  of  copper  formed  descends 
by  its  gravity  to  the  medal.  There  are,  no  doubt,  a  few  slight 
objections  to  placing  the  medal  under  the  positive  electrode — such 
as  the  impurities  in  the  copper  getting  disintegrated,  and  falling 
upon  the  surface,  but  a  piece  of  cloth  wrapped  round  the  pole  pre- 
vents this.  However,  when  a  fine  surface  is  wanted,  care  ought 
always  to  be  taken  to  have  clean  solutions  filtered,  and  kept  cov- 
ered from  dust ;  and  when  the  single  cell  is  used,  the  crystals  of 
sulphate  of  copper  should  be  suspended  in  a  fine  linen  bag,  or  the 
shelf  holding  them  be  lined  with  linen. 

EFFECTS  OF  DIFFERENCE  IN  THE  DENSITY  OF  SOLUTION. — Al- 
though in  principle  this  is  the  best  method,  we  believe  that  very 
few  practice  it,  because  of  the  trouble  attending  the  arrangement 
of  the  electrodes  in  this  position.  When  the  medals  are  small  the 
annoyances  from  unequal  density  are  not  so  material,  but  if  the 
surface  of  the  article  which  is  being  deposited  be  large — say  eight 
inches  or  upwards — the  difference  in  the  thickness  of  the  lower 
and  upper  portion  of  the  medal  is  very  great.  When  suspended 
perpendicularly,  they  should  be  shifted  several  times,  making  the 
upper  portion  the  lower,  besides  occasionally  stirring  the  solution, 
or  shaking  the  article.  Indeed  when  convenient,  the  article  re- 
ceiving the  deposit  should  be  kept  as  much  in  motion  as  possible, 
as  it  regulates  the  deposit,  making  it  smoother  and  less  brittle. 

CRYSTALS  OF  COPPER  ON  ELECTRODES. — It  will  be  found,  when 
working  with  a  battery,  that  the  sulphate  of  copper  solution  will 
become  stronger  round  the  positive  electrode,  which  is  gradually 
dissolved  by  the  transferred  acid.  A  frequent  effect  is,  that  the 
electrode  often  gets  coated  over  with  crystals  of  sulphate  of  cop- 
per, which  adhere  with  great  tenacity,  and  stop  the  electric  action. 
Under  such  circumstances,  it  is  only  necessary  to  clean  the  elec- 
trode from  the  crystals  and  to  add  a  little  water  to  the  solution, 
which  will  prevent  a  recurrence  of  the  crystals  for  a  time.  But 
the  stirring  of  the  solution  occasionally  will  do  much  to  prevent 
this  crystallization. 


ELECTROTYPE  PROCESSES.  563 


CHAPTER  XXVII. 

MISCELLANEOUS   APPLICATIONS   OF   THE   PROCESS   OF   COATING 
WITH   COPPER. 

BESIDES  the  applications  and  processes  which  we  have  described 
under  the  general  term  of  electrotyping,  there  are  various  applica- 
tions of  the  process  of  depositing  metals  upon  other  substances, 
which  have  been,  and  may  be  still  more  usefully  applied.  We 
may,  at  a  trifling  cost,  impart  a  coating  of  copper  to  cornices  for 
decorating  buildings,  to  terra  cotta,  engravings  on  wood,  etc.,  etc. 
Cloth  may  also  be  .easily  covered,  and  made  to  assume  the  appear- 
ance of  a  sheet  of  copper,  having  the  lightness  and  pliability  of 
cloth.  Lace  has  been  covered  with  copper,  and  used  for  battery 
plates,  and  has  also  been  gilt  and  made  into  beautiful  ornaments. 
Table-covers  with  metallic  ornaments  richly  gilt,  and  book-covers, 
have  all  been  tried  with  more  or  less  success,  although  they  have 
not  yet  been  profitably  produced. 

COPPERED  CLOTH. — Ordinary  cloth,  covered  with  copper,  was 
prepared  a  few  years  ago  in  considerable  quantities  for  the  cover- 
ing of  roofs,  wagons,  etc. ;  but  the  necessary  price  precluded  its 
use  when  competing  with  the  ordinary  materials  for  these  pur- 
poses, although  it  possesses  many  eminent  qualities  for  some  of 
these  uses — such  as  forming  fire-proof  covers  to  shelter  wagons 
from  the  sparks  discharged  by  a  locomotive.  The  choice  of  the 
kind  of  cloth  was  another  difficulty ;  linen  was  too  expensive,  and 
required  a  good  coating  of  copper  to  make  it  water-tight ;  the  best 
substance  was  a  felted  cotton  with  India-rubber,  but  after  a  few 
months  exposure  the  India-rubber  in  the  cloth  decomposed.  The 
operations  of  coating  cloth  with  copper  were  the  same  as  described 
for  the  wax  medals :  the  cloth  was  brushed  over  with  a  polish  of 
black  lead,  and  then  stretched  upon  a  frame  of  wood  having  a 
copper  band  round  it,  in  which  were  placed  small  hooks  or  pins, 
and  the  cloth  attached  to  these.  A  vat,  four  feet  deep  and  twelve 
yards  long,  was  made  of  brick  and  cement;  this  was  divided 
lengthwise  by  a  wooden  frame  with  panes  the  same  as  a  window, 
which  were  filled  in  with  unglazed  earthenware  plates,  cemented 
by  marine  glue,  and  the  whole  made  water-tight.  Into  one  divi- 
sion of  the  vat  were  placed  the  dilute  acid  and  sheets  of  zinc  ;  in 
the  other  the  solution  of  copper,  in  which  was  placed  the  cloth 
upon  the  frame.  The  arrangement  was  so  perfect  that  we  have 
often  seen  pieces  of  cloth,  twelve  yards  long  by  one  yard  wide, 
completely  covered  with  copper  in  one  hour.  The  result  of  many 
trials  was,  that  one  pound  weight  of  copper  gave  a  perfect  solid 
covering  to  twenty  superficial  square  feet  of  cloth. 

A  similar  thickness  is  quite  sufficient  for  other  surfaces  for  mere 
exposure  to  the  atmosphere,  such  as  wood- work,  cornices,  etc..  and 


564  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

may  be  produced  at  the  same  rate,  about  2s.  6d.  per  pound  of 
copper. 

Besides  these  applications,  many  others  have  been  suggested 
and  tried  with  variable  success.  Some  have  probably  been  aban- 
doned too  soon,  others  have  had  both  capital  and  talent  applied, 
and  success  is  yet  to  come.  We  shall  only  name  a  few  of  these 
applications. 

CALICO  PRINTERS'  ROLLERS. — So  early  as  1841  active  means 
were  tried  to  apply  the  electro-deposition  of  copper  to  the  prepara- 
tion of  rollers  for  printing  calicoes,  both  by  depositing  the  copper 
upon  wax  or  other  moulds,  to  make  an  entire  roller  of  copper,  or 
to  deposit  a  surface  of  copper  on  other  metals,  such  as  iron  or 
brass ;  but  none  of  them  have  yet  succeeded.  To  make  an  entire 
roller  is  much  more  expensive,  without  an  equivalent  advantage 
over  the  ordinary  method  of  casting,  rolling  and  boring.  To  de- 
posit a  layer  of  copper  on  iron  is  attended  with  many  practical 
difficulties,  both  in  protecting  the  iron  from  the  acid  solution  for 
so  long  a  time  as  is  required  to  deposit  the  proper  thickness,  and 
in  securing  the  adhesion  of  the  two  metals  during  the  subsequent 
operations.  It  requires  a  deposit  of  about  a  quarter  of  an  inch  in 
thickness  to  allow  for  turning  before  engraving.  There  is  then 
the  annealing  to  soften  the  copper,  etc.,  which  interferes  with  the 
adhesion  of  the  two  metals,  probably  from  their  different  rates  of 
expansion,  and  other  causes.  Similar  objections  may  be  made  to 
the  coating  of  brass  rollers  with  copper.  Numerous  and  varied 
have  been  the  experiments  made,  but  all  without  success ;  never- 
theless we  have  every  confidence  that  means  will  be  obtained  for 
producing  rollers  by  the  electro  process. 

ETCHING  OF  ROLLERS. — Another  application  of  the  process  to 
printers'  rollers  was  to  plate  the  surface  of  the  roller  with  silver  for 
the  purpose  of  etching.  The  engraving  is  then  made  through  the 
silver  coating ;  the  roller  is  next  passed  through  nitric  acid,  which 
acts  upon  the  exposed  copper,  the  silver  taking  the  place  of  var- 
nish in  ordinary  etching :  but  practical  difficulties  have  caused  the 
abandonment  of  this  application  also. 

PRINTING. — The  electro-metallurgical  process  has  been  applied  to 
many  operations  in  ordinary  printing.  Mr.  Warren  de  la  Rue  has 
been  eminently  successful  in  many  of  these  applications.  It  has  also 
been  applied  to  plates  for  printing  music,  and  for  embossing  soft 
materials,  such  as  leather.  By  depositing  a  sheet  of  copper  upon 
a  skin  of  morocco  leather,  it  may  be  used  for  imparting  an  im- 
pression to  other  skins  of  leather,  giving  them  the  appearance  of 
fine  morocco. 

The  printing  of  music  has  also  been  successfully  done  by  elec- 
trotyping  the  plate  from  a  stereotype  cast.  The  same  may  be  done 
from  ordinary  stereotype  plates. 

GLYPOGRAPHY.— A  process  which  Mr.  Palmer,  the  inventor, 
named  Glyphography,  has  been  one  of  the  most  successful  at- 
tempts to  apply  the  electrotype  to  the  art  of  engraving.  The 


ELECTROTYPE   PROCESSES.  565 

principle  of  the  invention  consists  in  depositing  copper  in  the 
grooves  or  engravings  made  in  a  layer  of  some  soft  substance 
spread  on  a  sheet  of  copper,  and  covering  the  whole  with  a  sheet 
of  electrotype  copper.  The  counterpart  of  the  engraving  thus 
produced  is  used  for  printing  from  in  the  same  manner  as  letter- 
press printers'  types  or  woodcuts.  It  may  therefore  be  called  a 
mode  of  stereotyping,  with  this  difference,  that  it  is  made  directly 
from  the  drawing  by  the  artist.  The  drawing,  however,  must  be 
made  in  a  particular  way,  which,  with  the  other  necessary  manipu- 
lations, is  thus  given  by  Mr.  Palmer :  * 

"A  piece  of  ordinary  copper  plate,  such  as  is  used  for  engraving, 
is  stained  black  on  one  side,  over  which  is  spread  a  very  thin  layer 
of  white  opaque  composition,  resembling  white  wax  both  in  its 
nature  and  appearance.  This  done,  the  plate  is  ready  for  use. 

"  In  order  to  draw  properly  on  these  plates  various  sorts,  of 
points  are  used  (according  to  the  directions  here  given),  which  re- 
move, wherever  they  are  passed,  a  portion  of  the  white  compo- 
sition, whereby  the  blackened  surface  of  the  plate  is  exposed,  form- 
ing a  striking  contrast  with  the  surrounding  white  ground,  so  that 
the  artist  sees  his  effect  at  once. 

"  The  drawing,  being  thus  completed,  is  put  into  the  hands  of 
one  who  inspects  it  very  carefully  and  minutely,  to  see  that  no  part 
of  the  work  has  been  damaged  or  filled-in  with  dirt  or  dust ;  from 
thence  it  passes  into  a  third  person's  hands,  by  whom  it  is  brought 
in  contact  with  a  substance  having  a  chemical  attraction  or 
affinity  for  the  remaining  portions  of  the  composition  thereon, 
whereby  they  are  heighted  ad  libitum.  Thus,  by  a  careful  manipu- 
lation, the  lights  of  the  drawing  become  thickened  all  over  the 
plate  equally,  and  the  main  difficulty  is  at  once  overcome.  A  little 
more  however  remains  to  be  done.  The  depth  of  these  non-print- 
ing parts  of  the  block  must  be  in  some  degree  proportionate  to 
their  width,  consequently  the  larger  breadths  of  lights  require  to 
be  thickened  on  the  plate  to  a  much  greater  extent  in  order  to  pro- 
duce this  depth.  This  part  of  the  process  is  purely  mechanical 
and  easily  accomplished. 

"It  is  indispensably  necessary  that  the  printing  surfaces  of  a 
block  prepared  for  the  press  should  project  in  such  relief  from  the 
block  itself  as  shall  prevent  the  probability  of  the  inking-roller 
touching  the  interstices  of  the  same  whilst  passing  over  them. 
This  is  accomplished  in  wood  engraving  by  cutting  out  these  in- 
tervening parts,  which  form  the  lights  of  the  print,  to  a  sufficient 
depth  ;  but  in  glyphography  the  depth  of  these  parts  is  formed  by 
the  remaining  portions  of  the  white  composition  on  the  olate, 
analogous  to  the  thickness  or  height  of  which  must  be  the  depth 
on  the  block,  seeing  that  the  latter  is,  in  fact  (to  simplify  the  mat- 
ter), a  cast  or  reverse  of  the  former.  But  if  this  composition  were 
. — . ^_ 

*  Glyphography,  or  engraved  drawing,  for  printing  at  the  typo  press  after 
the  inauner  of  woodcuts,  1844. 


566  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

spread  on  the  plate  as  thickly  as  required  for  this  purpose,  it 
would  be  impossible  for  the  artist  to  put  either  close,  fine,  or  free 
work  thereon  ;  consequently  the  thinnest  possible  coating  is  put  on 
the  plate  previously  to  the  drawing  being  made,  and  the  required 
thickness  obtained  ultimately  as  described. 

"  The  plate  thus  prepared  is  again  carefully  inspected  through  a 
powerful  lens,  and  closely  scrutinized  to  see  that  it  is  ready  for  the 
next  stage  of  the  process,  which  is  to  place  it  in  a  trough  and  sub- 
mit it  to  the  action  of  a  galvanic  battery,  by  means  of  which  copper 
is  deposited  into  the  indentations  thereof,  and,  continuing  to  fill 
them  up,  it  gradually  spreads  itself  all  over  the  surface  of  the  com- 
position until  a  sufficiently  thick  plate  of  copper  is  obtained,  which 
.on  being  separated  will  be  found  to  be  a  perfect  cast  of  the  draw- 
ing which  formed  the  clichee. 

"Lastly,  the  metallic  plate  thus  produced  is  soldered  to  another 
piece  of  metal  to  strengthen  it,  and  then  mounted  on  a  piece  of 
wood  to  bring  it  to  the  height  of  the  printer's  type.  This  com- 
pletes the  process,  and  the  glyphographic  block  is  now  ready  for 
the  press. 

"  It  should  however  have  been  stated  previously,  that  if  any 
parts  of  the  block  require  to  be  lowered,  it  is  done  with  the  greatest 
facility  in  the  process  of  mounting." 

This  process  has  however  not  come  into  much  use  as  a  substi- 
tute for  wood  engraving,  in  consequence  of  the  impossibility  of 
finding  a  suitable  varnish  for  the  use  of  the  artist  or  engraver.  It 
has,  in  fact,  given  way  to  another  process,  also  embraced  in  Mr. 
Palmer's  patent,  which  is  worked  thus  :  A  copper  plate  is  etched 
by  the  process  commonly  employed  by  engravers,  the  lines  being 
cut  into  the  copper  with  a  bold  stroke.  The  lines  are  then  bitten 
deeper  by  nitric  acid.  The  etching  is  made  direct,  not  reversed,  as 
it  is  upon  a  plate  that  is  to  be  worked  at  the  copperplate  press. 
When  the  engraving  is  ready,  the  etching  varnish  through  which 
the  drawing  is  cut  is  covered  with  a  conducting  substance,  and  an 
electrotype  plate  is  deposited  upon  the  etching.  When  this  is  re- 
moved from  the  mould  it  requires  to  be  trimmed,  for  it  is  impos- 
sible to  etch  a  plate,  or  to  bite  the  etching,  so  that  all  the  lines  shall 
be  exactly  of  the  same  depth.  To  remedy  this  the  face  of  the 
electrotype  is  levelled  by  grinding  and  burnishing.  The  following 
instructions  for  artists  are  published  by  the  patentee : 

INSTRUCTIONS  ON  GLYPHOGRAPHY  FOR  THE  AMATEUR.—"  The 
amateur  must  remember  that  he  is  producing  a  work  of  art  for  the 
surface  press,  and  not  for  copperplate  printing. 

"  The  drawing  or  etching  should  not  be°  made  with  lines  of 
equal  thickness  in  all  the  tints.  If  it  is  so  treated  with  a  thick  line, 
and  if  the  cross  hatching  be  kept  of  the  same  strength  as  the  prin- 
cipal line,  it  will  appear  like  a  coarse  pen-and-ink  drawing.  If  it 
is  treated  in  the  above  manner  with  a  fine  line,  and  the  work  laid 
very  close,  it  will  have  the  appearance  of  one  of  the  old  etchings. 
The  amateur,  therefore,  will  do  well  to  remark,  that  it  is  only  by  a 


ELECTROTYPE   PROCESSES.  567 

judicious  mixture  of  bold  and  delicate  work  that  beauty  of  style 
can  be  obtained;  and  as  the  darkest  shades  are  generally' foremost, 
and  become  gradually  lighter  to  the  distance,  so  that  the  darkest 
or  nearest  tones  should  generally  be  formed  by  the  boldest  work, 
and  gradually  increase  in  delicacy  to  the  offscape. 

"Etching  is  a  process  nearly  resembling  drawing  with  a  very 
fine  pen  or  pencil,  and  should  be  proceeded  with  as  follows : 

"Having  obtained  a  polished  copper-plate  with  an  etching  ground 
properly  laid,  proceed  to  put  your  design  upon  the  plate. 

"  If  it  is  a  print  or  miniature  that  is  being  copied,  you  must 
make  a  sketch  or  tracing  of  the  same  with  a  black  lead-pencil:  it 
must  then  be  traced  on  to  the  plate,  remembering  always,  that  the 
proof  from  the  block  will  be  in  the  same  position  as  the  etching; 
and  that  nothing  must  be  etched  or  written  backwards,  as  for  the 
ordinary  copperplate  printing. 

"  In  order  to  trace  the  object  on  to  the  plate,  take  a  piece  of 
transfer  paper,*  place  it  face  downwards  upon  the  plate,  secure  tbe 
corners  with  a  piece  of  wall  wax  or  paste,  or  hold  it  steadily  down, 
if  there  is  not  much  to  trace ;  then  place  on  your  sketch  or  trac- 
ing, go  over  the  outline  with  your  etching-needle  or  a  very  hard 
black  lead-pencil,  removing  a  corner  at  a  time  to  see  that  all  is 
correctly  transferred,  and  nothing  omitted,  or  that  the  outline  be 
not  too  heavy  and  thick,  in  which  case  you.  must  trace  lighter. 

"Having  thus  got^our  subject,  as  it  were,  sketched  upon  the 
plate,  proceed  in  all  respects  with  your  etching-needle  as  if  making 
a  drawing  with  a  black  lead-pencil,  only  working  more  firmly, 
taking  care  always  slightly  to  cut  the  copper. 

"  Be  careful  not  to  try  to  form  the  dark  touches  and  the  black 
parts  of  the  subject  with  a  number  of  lines  crossing  and  recrossing 
each  other,  but  scrape  them  away  entirely  with  the  point  of  your 
penknife,  or  any  other  convenient  instrument. 

"  In  commencing  the  etching  of  a  view,  it  is  usual  to  begin  with 
the  offscape,  etching  the  same  as  neatly  and  as  close  05  the  nature 
of  the  printing  ivill  admit,  working  more  firmly  and  boldly  in  every 
progressive  tone,  until  you  reach  the  foreground.  In  portraits  it 
is  usual  to  commence  with  the  eye ;  and  in  draperies  at  the  top, 
working  downwards. 

"  Owing  to  the  great  difference  between  surface  and  copperplate 
printing,  depth  of  tone  should  be  sought  as  *nuch  from  the  breadth 
or  thickness  of  the  lines,  as  from  laying  them  close  together ;  and 
on  the  contrary,  lightness  of  tint  must  be  obtained  by  the  distance 
of  the  lines  from  each  other,  as  well  as  from  their  delicacy. 

"  If  you  make  a  false  line,  or  wish  to  efface  any  portion  of  the 
work,  a  little  Brunswick  black  (which  can  be  procured  at  most  oil 
and  color  shops),  spread  thinly,  may  be  used  to  stop  it  out ;  or  rub 

*  To  prepare  the  transfer  paper,  take  some  thin  post  or  tissue  paper,  rub 
the  surface  well  with  black  lead,  vermilion,  red  chalk,  or  any  coloring  matter: 
wipe  this  preparation  well  off  with  a  piece  of  clean  raj;,  and  it  will  be  ri-adj 
for  use. 


568  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

a  little  of  the  superfluous  ground  from  the  side  of  the  plate  with  a 
camel's  hair  pencil  and  turpentine:  when  this  is  dry  the  work  can 
be  re-etched  and  finished  at  pleasure." 

This  last  process  has  afforded  some  excellent  work  in  the  shape 
of  maps,  among  which  we  may  cite  the  Penny  Atlas,  published  by 
Messrs.  Chapman  and  Hall.  Among  subjects  of  a  more  pictur- 
esque nature  executed  by  glyphography,  we  may  instance  Mr. 
George  Cruikshank's  etchings  of  The  Bottle.  These  are  sufficient 
to  show  that  the  art  of  electrotyping  engravings,  though  yet  in  its 
infancy,  promises  to  be  hereafter  of  importance  in  the  fine  arts. 

COPYING  OF  COPPERPLATE  ENGRAVINGS. — Copperplate  engrav- 
ings, of  all  sizes,  and  of  every  degree  of  excellence,  have  been 
copied  by  electrotype.  The  process  is  exactly  the  same  as  that  of 
making  a  copy  of  a  penny-piece,  as  described  at  page  533;  namelv, 
an  electrotype  mould  is  first  made  in  copper,  on  which,  of  course, 
the  engraving  appears  in  relief;  upon  which  mould  any  number  of 
electrotype  copies  of  the  copperplate  engraving  may  be  deposited 
successively.  The  duplicates  thus  made  are  accurate  copies  of  the 
original  engraving;  but  they  are  rapidly  worn  away  by  the  friction 
they  undergo  in  the  ordinary  process  of  copperplate  printing.  The 
process  has  therefore  not  displaced  the  use  of  engravings  on  steel. 

COATING  OF  GLASS  AND  PORCELAIN. — This  is  done  by  putting 
a  fine  coating  of  copal  varnish  over  the  glass,  then  black-leading 
it,  and  depositing  the  copper.  Another  metfiod  has  been  proposed, 
namely,  to  make  a  varnish  of  two  parts  asphaltum  and  one  part 
mastic,  by  fusing  these  together,  and,  when  cool,  dissolving  the 
mixture  in  spirits  of  turpentine  to  a  syrup  consistence.  To  pre- 
vent the  deposit  coming  off  the  glass,  the  vessel  is  first  corroded 
by  the  fumes  of  hydrofluoric  acid.  A  solution  of  gutta  percha  or  . 
benzole  has  also  been  proposed  as  a  varnish  for  fixing  on  the* 
black-lead  and  deposit.* 

Eetorts,  basins,  and  other  chemical  vessels,  are  sometimes  cov- 
ered with  copper  for  their  protection  during  boiling  and  evapora- 
tion. China  saucepans  have  also  been  made  and  covered  with 
copper  to  take  the  place  of  tinned  copper  vessels,  but  the  adhesion 
of  the  metal  upon  these  substances,  even  when  we  attempt  to  secure 
it  by  the  means  above  referred  to,  is  never  so  perfect  but  that  after 
a  short  use  the  deposit  of  copper  loosens  from  the  vessels.  There 
is  then  great  liability  for  liquids  to  get  between  the  coating  and 
the  vessel,  and  when  heat  is  afterwards  applied  these  liquids  satu- 
rated with  verdigris  boil  out.  Consequently  such  coverings  are 
not  well  adapted  either  for  culinary  purposes  or  delicate  chemical 
operations.  They  have,  notwithstanding,  been  highly  recom- 
mended, and  the  practice  of  covering  the  bulbs  of  large  plain  re- 
torts, etc.,  may  be  useful  in  a  few  large  manufacturing  operations, 
but  our  experience  is  certainly  not  favorable  to  their  general  use. 

Mr.  John  Kidgway,  of  Cauldon-place,  Staffordshire,  china  manu- 

*  Progress  of  General  Science,  vol.  ii. ;  and  Phartn.  Journal,  vol.  viii. 


ELECTROTYPE   PROCESSES.  569 

facturer,  has  recently  patented  certain  improvements  in  the  method 
or  process  of  ornamenting  or  decorating  articles  of  glass,  china, 
earthenware,  or  other  ceramic  manufactures.  In  the  specification 
of  his  patent,  just  enrolled,  Mr.  Ridgway  states  that  his  first  object 
is  to  apply  a  new  glaze,  which  shall  enable  the  metallic  coating  to 
adhere  firmly,  by  capillary  attraction,  and  give  affinity  for  copper 
as  a  first  coating.  In  pursuance  of  this,  he  first  submits  the 
article  to  an  alcoholic  solution,  or  a  gelatinous  solution.  He  then 
brushes  over  it  an  impalpable  powder,  composed  of  half  carburet 
of  iron,  and  half  sulphate  of  copper.  The  article  thus  treated  is 
then  to  be  corroded  by  the  fumes  of  hydrofluoric  acid.  The  article 
is  then  to  be  smoothed,  by  brushing  it  over  with  silver  sand,  or  by 
the  scratch-brush ;  but  when  the  shape  and  nature  of  the  article 
will  not  admit  of  this,  it  is  to  be  plunged  into  a  liquor,- consisting 
of  6  quarts  sulphuric  acid,  4  quarts  aquafortis,  f  oz.  muriatic  acid, 
and  6  quarts  water.  Grease  is  to  be  carefully  removed  from  the 
article,  and  a  thin  film  of  mercury  is  to  be  applied.  The  solution 
of  copper  consists  of  1  sulphate  of  copper,  and  4  filtered  water. 
Suitable  solutions  for  silvering  or  gilding  are  to  be  applied,  in  ac- 
cordance with  the  practice  of  electrotyping.  The  claim  is  not  to 
the  solutions  the  coating  as  such,  but  to  the  application  of  "  elec- 
trotyping," or  electro-metallurgy,  to  the  objects  stated  in  the  title, 
provided  the  articles  be  so  prepared  as  to  allow  them  to  combine 
from  an  alloy  with  them. 

ON  GALVANIC  SOLDERING. — Among  the  many  applications  of 
the  deposition  of  metals,  there  is  one  we  have  been  often  asked 
about,  namely,  if  it  would  not  be  possible  to  solder  different  metals 
together  by  that  process.  The  following  article,  which  is  taken 
from  the  Technologist,  will  give  a  full  reply  to  all  who  may  be 
still  inquiring  for  this  application: 

"  Under  the  name  of  galvanic  soldering,  a  process  is  known  by 
means  of  which  two  pieces  of  metal  may  be  united  by  means  of 
another  metal,  which  is  precipitated  thereon  through  the  agency 
of  a  galvanic  current.  This  mode  of  soldering  by  the  'wet 
method'  has  been  often  recommended  in  various  periodicals  relating 
to  the  industrial  arts ;  but  it  has  been  objected  that,  practically 
speaking,  the  union  between  two  pieces  of  metal  could  not  be 
effected  by  means  of  a  metal  precipitated  by  galvanic  agency.  In 
order,  however,  to  arrive  at  a  definite  conclusion  upon  this  ques- 
tion, M.  Eisner  undertook  the  following  experiments,  the  results  of 
which  are  in  favor  of  the  practical  use  of  the  operation  of  solder- 
ing by  galvanic  agency.  In  conducting  these  experiments,  the 
kind  of  battery  known  as  Daniell's  'constant  battery'  was  em- 
ployed ;  and  upon  the  end  of  the  copper  wire,  which  formed  the 
negative  electrode,  a  strong  ring  of  sheet-copper  was  placed.  This 
ring  was  cut  asunder  at  one  point,  and  the  distance  left  between 
the  several  parts  was  about  the  sixtieth  of  an  inch.  At  the  end 
of  a  few  days  (during  which  time  the  exciting  liquors  were  sev- 
eral times  renewed)  the  space  in  the  severed  portion  of  the  ring 


570  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

was  completely  filled  up  with  copper  regulus,  which  had  "been  pre- 
cipitated ;  and  on  partially  cutting  with  a  file  through  the  part 
thus  filled  up,  and  examining  it  with  a  lens,  it  was  observed  to  be 
very  equally  filled  with  solid  and  coherent  copper. 

"  Another  copper  ring  was  then  cut  into  two  parts,  and  the  two 
semi-angular  segments  thus  obtained  were  placed  with  the  faces  of 
the  sections  opposite  each  other,  and  submitted  to  the  action  of  a 
galvanic  current.  At  the  end  of  a  few  days,  the  segments  were 
united  by  the  copper  precipitated,  thus  forming  again  a  complete 
ring.  It  was  also  found  in  this  case,  on  removing  with  a  file  a 
portion  of  the  thickness  of  the  ring  at  the  points  of  contact,  that 
the  spaces  had  been  completely  filled  up  by  copper  galvanically 
precipitated,  which  had  united  the  whole.  On  observing  these 
points  carefully  with  a  lens,  the  regular  deposition  of  the  copper 
could  be  readily  traced  between  the  formerly  separated  portions  of 
the  ring. 

"A  third  experiment  was  made  in  the  following  manner  :  Two 
strong  rings  of  sheet-copper  were  laid  with  their  freshly-cut  faces 
one  upon  another,  so  that  the  two  rings  constituted  a  cylinder. 
These  rings  were  surrounded  by  a  band  of  sheet-tin  which  was 
coated  with  a  solution  of  wax,  so  that  the  two  rings  were  equally 
surrounded  by  a  conducting  material.  Thus  disposed,  these  rings 
were  attached  to  the  negative  wire  of  the  battery  and  immersed 
in  the  bath  of  sulphate  of  copper.  At  the  end  of  a  few  days  the 
interior  surface  of  the  rings  was  covered  with  precipitated  copper, 
and  between  the  contact  surfaces  of  the  two  rings  copper  was  also 
precipitated.  These  rings  had  only  been  submitted  to  the  gal- 
vanic current  to  such  an  extent  as  to  cover  their  interior  surface 
with  a  thin  coating  of  precipitated  copper,  and  yet  they  were 
already  completely  re-united,  and  formed  a  cylinder  consisting  of 
a  single  piece.  The  exterior  conducting  covering,  consisting  of 
a  sheet  of  tin,  was  of  course  removed  before  testing  the  cohesion 
or  persistence  of  the  galvanic  precipitate.  It  may  be  remarked 
that  these  rings,  after  being  for  a  certain  time  in  contact  (during 
the  galvanic  action),  together  with  the  plate  of  copper  upon  which 
they  rested,  became  so  encrusted  with  precipitated  metallic  copper 
that  some  force  was  found  necessary  to  effect  their  detachment 
from  the  copper  wire. 

"  There  would  appear  to  be  no  doubt,  then,  according  to  the 
results  obtained  in  the  preceding  experiments,  that  two  pieces  of 
metal  may  be  firmly  united  by  means  of  galvanically-precipitated 
copper :  in  a  word,  that  soldering  by  galvanic  agency  is  perfectly 
practicable.  It  will  therefore  be  possible  to  firmly  unite  the  dif- 
ferent parts  of  a  large  piece  of  metal,  and  to  make  a  perfect  figure 
of  them  by  galvanic  precipitation  of  a  metal  (copper,  in  ordinary 
cases).  If  solutions  of  salts  of  gold  or  silver  were  employed  in  as 
concentrated  a  form  as  those  of  copper  above  mentioned,  there  is 
reason  to  believe  that  galvanic  soldering  would  also  result.  In 
fact,  M.  de  Hackewitz  states  that  in  some  experiments  on  a  larger 


ELECTROTYPE   PROCESSES.  571 

scale  which  he  undertook,  to  obtain  hollow  figures  by  galvano- 
plastic  means,  he  had  remarked  that  galvanic  union  often  took 
place  between  the  pieces  operated  upon.  M.  Eisner  states  that 
while  conducting  the  experiments  above-mentioned,  he  remarked 
that  by  employing  too  powerful  a  current,  the  negative  electrodes 
of  copper,  and  even  the  plate  of  copper,  and  ring  of  the  same  metal 
resting  thereon,  became  covered  with  a  deep  brown  substance,  in 
the  same  manner  as  this  occurs  under  similar  circumstances  in  gal- 
vanic gilding,  as  is  well  known.  After  several  unsuccessful 
attempts  to  prevent  the  formation  of  this  brown  coating,  M.  Eisner 
found  that  it  was  possible  to  remove  it  entirely  on  immersing  the 
articles  covered  therewith  during  a  few  seconds  in  a  mixture  of 
sulphuric  and  nitric  acids.  By  this  means  the  precipitated  copper 
was  made  to  assume  its  natural  red  color.  The  possibility  of  prac- 
tically effecting  the  operation  of  soldering  by  galvanic  agency  may 
be  explained  in  a  few  words,  in  a  theoretical  point  of  view.  The 
article  is  in  fact  in  an  electro-negative  state  of  excitation,  whilst 
the  zinc  operates  positively.  The  result  is,  that  the  faces  which 
are  placed  opposite  each  other,  when  the  ring  has  been  cut,  are 
negative ;  that  is  to  say,  in  an  electric  condition  of  the  same  de- 
nomination. During  the  progress  of  the  electrolytic  decomposition 
of  the  metallic  salt  in  solution  (sulphate  of  copper  in  the  above 
case),  the  electro-positive  molecules  of  copper  which  are  detached 
simultaneously  arrange  themselves  upon  the  two  opposite  faces, 
and  in  the  direction  of  the  break.  Now,  from  the  moment  that 
these  molecules  are  deposited,  they  constitute  with  the  piece  a 
homogeneous  mass,  and  from  that  time  act  negatively  upon  the 
copper  which  is  contained  in  the  solution,  and  again  precipitate 
copper  in  the  form  of  regulus.  This  method  of  operation  con- 
tinues until  the  space  which  existed  between  the  two  separate 
pieces  of  metal  is  filled  up  with  metallic  copper — in  fact  the  layers 
of  copper  which  become  deposited  in  an  equal  manner  upon  the 
contiguous  faces  of  the  metal  gradually  diminish  the  distance  which 
separated  the  latter,  until  at  length  the  metallic  layers  which  cross 
in  the  opposite  direction  meet  each  other ;  the  result  being,  that 
the  whole  of  the  break  which  originally  existed  between  the  faces 
will  have  disappeared  and  become  filled  up  with  copper. 

"With  respect  to  the  solidity  (the  degree  of  cohesion)  of  the 
galvanic  soldering,  it  is  the  same  as  that  of  copper  or  other  metal 
precipitated  by  galvanic  agency.  It  will  moreover  be  well  under- 
stood that  too  energetic  galvanic  excitation  must  have  an  injurious 
influence  upon  the  cohesion  of  the  metal  precipitated ;  and  in  this 
case  precisely  the  same  phenomena  will  be  observed  as  those  which 
have  long  manifested  themselves  in  ordinary  galvano-plastic  oper- 
ations."— L.  ELSNER,  Technologist. 

We  mention  another  application  of  the  electro  deposition,  which 
might  be  extended. 

GALVANO-PLASTIC  NIELLO. — Niello,  a  peculiar  style  of  enamel- 
ling, consists  in  engraving  or  stamping  figures  on  a  plate  of  silver 


572  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

or  gold,  and  then  filling  the  incised  lines  or  impressed  pattern  with 
a  sort  of  enamel — differing,  however,  from  true  enamel — which  is 
a  kind  of  glass,  by  being  formed  of  a  mixture  of  the  sulphurets 
of  lead,  silver,  and  copper.  This  mixture  is  of  a  black  color — 
hence  the  name  niello,  from  nigellum,  derived  from  niger,  black — 
and  when  melted  into  the  intaglio  parts  of  a  plate  gives  it  some- 
what the  appearance  of  an  inked  engraved  copperplate.  A  new 
kind  of  niello  work  has  lately  been  introduced  on  the  Continent, 
in  which,  however,  the  figures  are  not  produced  by  an  enamel  of 
sulphuret  of  silver,  as  in  the  true  niello,  but  by  a  different-colored 
metal ;  thus  on  a  plate  of  gold  may  be  produced  fine  engravings, 
the  lines  of  which  are  in  silver,  and  so  on.  This  can  be  effected 
in  two  ways :  first,  by  covering  the  plate  to  be  ornamented  with  a 
varnish  exactly  as  is  used  in  etching ;  the  pattern  or  ornament  is 
then  to  be  engraved  on  this  varnish,  and  the  metallic  surface 
etched  out  to  the  proper  depth.  The  engraved  plate  is  to  be 
placed  in  a  solution  of  the  metal  intended  to  form  the  pattern,  and 
a  deposit  allowed  to  form  in  the  usual  way  adopted  in  all  galvano- 
plastic  works.  When  the  intaglio  lines  have  been  completely 
filled  up  by  the  deposited  metal,  the  plate  is  removed  from  the 
solution  and  ground,  when  the  pattern  will  be  fully  developed. 
The  second  method  consists  in  sketching  the  ornament  on  a  sheet 
of  paper  with  lithographic  ink,  placing  this,  with  the  side  upon 
which  the  drawing  was  made,  upon  a  plate  of  silver  or  other  metal 
to  be  ornamented,  and  pressing  them  together ;  the  paper  is  now 
removed  with  water,  slightly  acidified,  leaving  the  ink  adhering  to 
the  plate,  which  is  to  be  sprinkled  with  sand.  When  the  ink  has 
fully  dried,  the  sand  is  blown  away ;  the  plate  is  placed  in  a  solu- 
tion of  the  metal  which  it  is  intended  should  form  the  ground,  and 
put  in  connection  with  the  battery.  By  this  means  a  deposit  will 
be .  formed  over  the  whole  surface,  except  the  parts  protected  by 
the  ink.  On  the  removal  of  the  latter  with  alcohol  or  spirits  of 
turpentine,  etc.,  the  original  metal  will  be  exposed,  forming  a  pat- 
tern. Many  highly  ornamental  and  useful  applications  might  be 
made  of  these  processes,  especially  in  the  manufacture  of  church 
furniture.  Instead  of  simply  engraving  the  name  and  legend  upon 
pieces  of  plate  presented  to  persons,  it  might  be  put  in  in  letters 
of  gold  at  very  little  more  expense. 


CHAPTEE  XXVIII. 

BRONZING. 


WE  have  already  mentioned  that  when  a  medal  has  been  made 
from  a  metallic  mould,  protected  by  a  little  wax  dissolved  in  tur- 
pentine, it  retains  its  bright  copper  lustre  for  a  long  time,  even 


BRONZING.  573 

when  exposed  to  the  air ;  but  generally  the  copper  medals  and  other 
objects  are  very  liable  to  tarnish,  for  which  reason  it  is  usual  to 
give  them  a  coating  of  bronze,  that  they  may  acquire  a  permanently 
agreeable  appearance. 

BROWN  BRONZES. — Bronzing  is  effected  by  several  very  simple 
methods,  the  most  common  of  which  is  the  following : 

Take  a  wine-glass  of  water,  and  add  to  it  four  or  five  drops  of 
nitric  acid ;  with  this  solution  wet  the  medal  (which  ought  to  have 
been  previously  well  cleaned  from  oil  or  grease)  and  then  allow  it 
to  dry;  when  dry  impart  to  it  a  gradual  and  equable  heat,  by  which 
the  surface  will  be  darkened  in  proportion  to  the  heat  applied. 

ANOTHER  METHOD. — Make  a  thin  paste  of  crocus  and  water :  lay 
this  paste  on  the  face  of  the  medal,  which  must  then  be  jfut  into  an 
oven,  or  laid  on  an  iron  plate  over  a  slow  fire ;  when  the  paste  is 
perfectly  reduced  to  powder,  brush  it  off  and  lay  on  another  coat- 
ing ;  at  the  same  time  quicken  the  fire,  taking  care  that  the  addi- 
tional heat  is  uniform;  as  soon  as  the  second  application  of  paste  is 
thoroughly  dried,  brush  it  off.  The  medal  being  now  effectually 
secured  from  grease,  which  often  occasions  failures  in  bronzing, 
coat  it  a  third  time,  but  add  to  the  strength  of  the  fire,  and  sustain 
the  heat  for  a  considerable  time:  a  little  experience  will  soon  enable 
the  amateur  to  decide  when  the  medal  may  be  withdrawn ;  the  third 
coating  being  removed,  the  surface  will  present  a  beautiful  brown 
bronze.  If  the  bronze  is  deemed  too  light  the  process  can  be 
repeated. 

Another  very  simple  method  is  this :  after  the  medal  is  well 
cleaned  from  wax  or  grease,  by  washing  it  in  a  little  caustic  alkali, 
brush  some  black  lead  over  the  face*  of  it,  and  then  heat  it  in  the 
same  way  as  described  for  crocus;  or  a  thin  paste  of  black  lead  may 
be  used,  and  the  processes  already  referred  to  be  repeated  until  the 
desired  brown  tint  is  obtained.  In  this  kind  of  bronze  a  little 
Hematitic  iron  ore,  which  has  an  unctuous  feel,  may  be  brushed 
over  the  face  of  the  bronze,  by  which  a  beautiful  lustre  is  imparted 
to  it,  and  a  considerable  variety  in  the  shade  may  be  obtained.  In 
the  brown  bronzes  the  copper  is  slightly  oxidized  on  the  surface. 

BLACK  BRONZES. — A  very  dark  colored  bronze  may  be  obtained 
by  using  a  little  sulphuretted  alkali  (sulphuret  of  ammonia  is  best). 
The  face  of  the  medal  is  washed  over  with  the  solution,  which 
should  be  dilute,  and  the  medal  is  to  be  dried  a,t  a  gentle  heat.  It 
should  afterwards  be  polished  by  a  hard  hair  brush.  Sulphuretted 
hydrogen  gas  is  sometimes  employed  to  give  this  black  bronze, 
but  the  effect  of  it  is  not  so  good,  and  the  gas  is  very  deleterious 
when  breathed.  In  these  bronzes  the  surface  of  the  copper  is  con- 
verted into  a  sulphuret. 

Many  metallic  solutions,  such  as  weak  acid  solutions  of  platinum, 
gold,  palladium,  antimony,  etc.,  will  impart  a  dark  color  to  the 
surface  of  medals  when  they  are  dipped  into  them.  The  medal 
after  being  dipped  into  the  metallic  solution  is  to  be  well  washed 
and  brushed.  In  such  bronzes  the  metals  contained  in  the  solu- 


574  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

tion  are  precipitated  upon  the  face  of  the  copper  medal,  which 
effect  is  accompanied  by  a  partial  solution  of  the  copper. 

GREEN  BRONZES. — Green  bronzes  require  a  little  more  time  than 
those  already  described.  They  depend  upon  the  formation  of  an 
acetate,  carbonate,  or  other  green  salt  of  copper  upon  the  surface 
of  the  medal.  Steeping  for  some  days  in  a  strong  solution  of  com- 
mon salt  will  give  a  partial  bronzing  which  is  very  beautiful,  and 
if  washed  in  water,  and  allowed  to  dry  slowly,  is  very  permanent. 
Sal  ammoniac  may  be  substituted  for  common  salt.  Even  a  strong 
solution  of  sugar,  alone,  or  with  a  little  acetic  or  oxalic  acid,  will 
produce  a  green  bronze ;  so  also  will  exposure  to  the  fumes  of  dilute 
acetic  acid,  to  weak  fumes  of  hydrochloric  acid,  and  to  several 
other  vapbrs.  A  dilute  solution  of  ammonia  allowed  to  dry  upon 
the  copper  surface  will  leave  a  green  tint,  but  not  very  permanent. 

Electrotypes  may  also  be  bronzed  green,  having  the  appearance 
of  ancient  bronze,  by  a  very  simple  process:  take  a  small  portion 
of  bleaching  powder,  place  it  in  the  bottom  of  a  dry  vessel,  and 
suspend  the  medal  over  it,  and  cover  the  vessel :  in  a  short  time 
the  medal  will  take  on  a  green  coating,  the  depth  of  which  may  be 
regulated  by  the  quantity  of  bleaching  powder  used,  or  the  time 
that  the  medal  is  suspended  in  its  fumes :  of  course  any  sort  of 
vessel,  or  any  means  by  which  the  electrotype  may  be  exposed  to 
the  fumes  of  the  powder,  will  answer  the  purpose :  a  few  grains  of 
the  powder  is  all  that  is  required.  According  as  the  medal  is 
clean  or  tarnished,  dry  or  wet,  when  suspended,  different  dints 
with  different  degrees  of  adhesion  will  be  obtained. 

The  green  bronzes  are  generally  applied  to  figures  and  busts. 

These  directions  and  hints  will  enable  the  student  to  vary  his 
bronzes.  Practice  will  give  him  perfection,  and  enable  him  to  fix 
upon  that  which  best  pleases  his  taste.  Scarcely  two  electrotypists 
agree  upon  the  same  method  of  bronzing,  but  differ  in  some  little 
details  of  practice,  or  on  some  point  of  taste.  Each  prefers  the 
plan  that  has  given  to  him  his  best  results,  and  which  he  can 
hardly  impart  by  description  to  another. 

Should  the  electrotypist  wish  to  coat  the  copper  medal  with 
another  metal,  as  silver  and  gold,  directions  will  be  given  under 
plating  and  gilding  how  to  proceed  to  effect  his  purpose. 


CHAPTER  XXIX. 

DEPOSITION   OF   METALS   UPON   ONE  ANOTHER. 

COATING  OF  IRON  WITH  COPPER.— Besides  making  articles  of 
solid  copper,  we  may  at  a  small  cost  give  a  coating  of  copper  to 
another  metal,  such  as  iron,  which  if  kept  in  a  dry  place,  will  retain 


COATING  OP  IKON  WITH   CGP*V!il.  575 

the  appearance  of  copper  for  any  length  of  time.  But  in  covering 
iron  with  copper,  or  any  one  metal  with  another,  great  care  must  be 
taken  that  a  proper  kind  of  solution  be  used. 

It  is  a  familiar  fact,  that  if  a  piece  of  iron,  such  as  the  blade  of  a 
knife,  be  dipped  into  a  solution  of  sulphate  of  copper,  it  receives  a 
coating  of  that  metal.  This  is  often  described  as  the  result  of  gal- 
vanic action,  but  there  is  no  more  galvanic  action  in  this  than  in 
any  ordinary  chemical  combination;  it  is  simply  a  case  of  chemical 
substitution ;  the  acid  that  is  in  union  with  the  copper  having  a 
stronger  attraction  for  iron,  leaves  the  copper,  and  combines  with 
the  iron:  the  copper  is  left  on  the  surface  of  the  iron,  but  the  two 
metals  not  having  sufficient  polar  attraction  to  cause  them  to  adhere 
so  firmly  as  to  exclude  the  action  of  the  acid,  the  copper  is  under- 
mined, and  fells  to  the  bottom  of  the  solution  as  a  powder.  After 
some  copper' has  fallen  upon  the  surface  of  the  iron,  local  galvanic 
action  is  induced  between  it  and  the  iron;  but  this  secondary 
action  is  altogether  distinct  from  that  which  first  takes  place. 

Any  solution  that  has  the  power  to  give  a  metallic  coating  to  a 
metal  when  dipped  into  it,  should  not  be  used  to  coat  that  metal 
by  electricity. 

The  attraction  of  the  common  mineral  acids  for  the  ordinary 
metals  is  as  follows :  Zinc,  iron,  copper,  nickel,  silver,  gold,  pla- 
tinum. 

If  the  metal  to  be  deposited  be  copper  held  in  solution  by  an 
acid,  say  sulphuric  acid,  then  iron  or  zinc  cannot  be  coated  with 
copper  from  this  solution ;  the  acid  having  a  greater  attraction  for 
these  metals,  will  leave  the  copper  and  combine  with  them  as  de- 
scribed above :  but  if  the  metal  to  be  coated  be  any  of  those  under 
copper,  in  the  above  table,  then  no  chemical  action  will  take  place, 
and  no  deposit  will  be  made,  except  as  the  eff'eclj  of  the  .electric 
current  introduced  by  the  battery.  This  we  believe  is  the  cause 
why  De  la  Rive,  Spencer,  and  others,  failed,  at  an  early  stage  of 
the  art,  in  their  experiments  in  plating  and  gilding,  as  they  em- 
ployed acid  solutions,  which  are  quite  impracticable  when  used  for 
depositing  upon  inferior  metals.  Under  these  circumstances,  other 
solvents  for  the  metals  must  be  used,  which  have  a  different  rela- 
tive attraction  for  the  metals  than  the  acids  have.  The  substance 
first  applied  for  this  purpose  is,  after  sixteen  years  experience,  still 
found  to  be  the  best — namely,  cyanide  of  potassium. 

CYANIDE  OF  POTASSIUM. — This  substance  may  be  prepared  by 
exposing  ferrocyanide  of  potassium  (yellow  prussiate  of  potash)  to 
a  red  heat  in  an  iron  crucible ;  then  pounding  the  mass,  and  boil- 
ing it  in  alcohol  of  about  spec.  grav.  0'900:  cyanide  of  potassium 
crystallizes  on  cooling  the  resulting  solution.  It  is  now,  however, 
almost  universally  prepared  for  electro-metallurgical  purposes,  by 
a  process  which  was  first  suggested  by  Messrs.  F.  and  E.  Rodgers, 
but  afterwards  more  fully  explained  by  Professor  Liebig,  and  hence 
called  "Liebig's  Process:"  it  is  at  once  both  simple  and  easy  of 
performance. 


576  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

Ferrocyanide  of  potassium,  pounded  fine,  is  dried  over  a  slow 
fire  (we  have  found  an  iron  plate,  or  clean  shovel,  to  serve  the  pur- 
pose very  well) :  it  must  be  constantly  stirred  to  prevent  its  form- 
ing a  cake  upon  the  hot  iron ;  when  perfectly  free  from  moisture,  8 
parts  must  be  thoroughly  well  mixed  with  three  parts  of  carbonate 
of  potash,  also  well  dried :  put  a  cast-iron  crucible  into  the  fire,  and, 
when  it  is  red  hot,  nearly  fill  it  with  the  mixture,  and  keep  up  the 
heat  by  occasional  augmentations  of  fuel :  the  crucible  should  be 
kept  covered  as  much  as  possible.  In  a  short  time  the  whole  fuses 
into  a  beautiful  liquid  with  the  evolution  of  gas.  It  should  be  kept 
in  this  state  for  10  or  15  minutes,  being  occasionally  stirred  with 
an  iron  rod :  the  portion  adhering  to  the  red  should  be  examined 
from  time  to  time,  and  when  the  liquid  on  it  cools  white,  it  is  an 
indication  that  it  is  ready  to  be  removed  from  the  fire ;  but  the  first 
time  a  cast-iron  crucible  is  used,  this  test  will  not  be  so  accurate, 
the  salt  having  then  a  light  gray  color.  When  the  crucible  is 
removed  from  the  fire,  it  should  be  placed  upon  a  stone,  the  mass 
stirred,  and  then  allowed  to  settle  for  a  short  time,  after  which  the 
clear,  or  liquid  part,  is  to  be  poured  off  into  a  clean  iron  vessel. 
The  sediment  should  be  scraped  clean  out  of  the  crucible  while  it 
is  hot,  as  the  crucible  will  do  to  use  again  several  times ;  but  if  the 
mass  at  bottom  be  allowed  to  cool  it  will  be  difficult  to  remove  it 
from  the  crucible  afterwards.  The  clear  liquid  poured  off  is  cyanide 
of  potassium,  having  from' 25  to  30  per  cent,  of  cyanate  of  potash, 
and  other  impurities  generally  contained  in  commercial  yellow 
prussiate  of  potash :  80  per  cent,  of  cyanide  of  potassium  is  the 
greatest  proportion  that  this  process  can  give.  We  have  occa- 
sionally obtained  it  at  78  per  cent,  from  commercial  materials,  but 
more  generally  at  70  and  72  per  cent ;  and  we  have  found  cyanide 
of  potassium  in  the  market  containing  as  little  as  49  per  cent,  of 
pure  cyanide. 

The  results  of  the  manufacture  of  this  salt  on  a  large  scale,  from 
the  ordinary  materials  of  commerce,  show  that  55  Ibs.  of  yellow 
prussiate,  dried  as  directed  above,  yield  48  Ibs. ;  and  19  Ibs.  of 
carbonate  of  potash  give  18  Ibs.  of  dry  salts ;  in  all  66  Ibs.  of  the 
proper  mixture.  The  crucible  used  was  of  this  shape, 
Fig.  579,  capable  of  holding  -from  two  to  three  pints ;  FiS- 
in  general  two  of  them  were  used  up  in  making  the 
above  quantity  of  cyanide,  even  when  great  care  was 
taken.  One  great  cause  of  the  crucible  giving  way  is 
the  depth  of  the  fire,  and  openness  of  the  bars  of  the 
grate.  The  bottom  of  the  crucible,  between  each  pair 
of  bars,  fuses  from  the  great  heat  concentrated  near  the  opening. 
To  remedy  this  evil,  a  square,  .tile  of  fire-clay  should  be  laid  upon 
the  bars  upon  which  the  crucible  is  to  rest.  The  tile  must  not 
cover  all  the  bars,  else  the  draught  will  be  stopped— an  equal 
space  must  be  left  at  each  side  of  the  tile,  which  will  preserve  a 
regular  heat  around  the  crucible. 

The  quantity  of  clean  cyanide  of  potassium  obtained  from  the 


COATING  OF  IKON  WITH  COPPER.  577 

above  quantity  of  materials  was  about  38  Ibs.;  the  sediment 
scraped  out  of  the  crucible,  being  put  into  water,  yielded  about  6 
Ibs.  more  in  solution,-  but  of  inferior  quality — good  enough,  how- 
ever, for  precipitations,  the  cleaning  of  silver,  and  other  general 
purposes  in  the  factory. 

It  may  be  mentioned  that  in  these  operations  the  crucible  is 
never  allowed  to  cool,  but  as  soon  as  the  sediment  is  scraped  out, 
it  is  again  put  into  the  furnace.  If  the  iron  sediment  is  not  well 
cleaned  out,  it  imbibes  oxygen  rapidly,  and  the  charge  next  taken 
from  the  crucible  will  have.an  excess  of  cyanate  of  potash,  besides 
lessening  the  capacity  of  the  crucible.  Generally  speaking,  how- 
ever, even  when  the  utmost  care  is  taken,  the  last  charge  has  more 
cyanate  of  potash  than  the  first. 

CYANIDE  OF  COPPER. — To  prepare  copper  solutions  by  means 
of  cyanide  of  potassium,  for  covering  iron  and  other  positive 
metals,  there  are  several  methods. 

First  Method. — To  a  solution  of  sulphate  of  copper,  add  by  de- 
grees a  solution  of  cyanide  of  potassium,  which  will  give  a  yel- 
lowish green  precipitate,  with  slight  effervescence.  There  will  be 
evolved  a  gas,  having  a  most  pungent  odor,  to  prevent  the  inhala- 
tion of  which  the  most  watchful  carefulness  has  to  be  exercised,  as 
it  is  very  deleterious.  It  will  be  found  that  the  copper  is  not  all 
precipitated  by  the  cyanide  of  potassium,  for  according  to  this 
mode,  when  a  precipitate  ceases  to  be  formed,  the  solution  remains 
greenish  blue,  probably  owing  to  the  decomposition  of  the  cyanate 
of  potash,  and  the  formation  of  ammonia,  which  holds  copper  in 
solution,  and  forms  also  some  complicated  compounds  with  the 
cyanides  of  copper.  If  cyanide  of  potassium  is  added  until  the 
blue  solution  disappears,  still  copper  is  held  in  the  solution,  and 
may  be  detected  by  taking  out  a  little,  and  adding  to  it  a  few  drops 
of  sulphuric  acid,  which  will  give  a  white  precipitate  of  subcyanide 
of  copper.  The  loss  of  copper  sustained  is  the  only  objection  to 
this  mode  of  preparing  a  copper  solution.  The  cyanide  of  potas- 
sium is  added  until  a  precipitate  is  no  longer  formed ;  it  is  then 
allowed  to  settle,  the  clear  liquid  is  poured  off,  and  the  vessel  is  to 
be  filled  with  water :  when  the  precipitate  has  again  settled,  the 
liquor  is  poured  oft^  and  this  washing  is  repeated  four  or  five  times, 
in  order  to  wash  out  the  sulphate  of  potash  which  is  formed  during 
the  precipitation.  After  being  thus  washed,  a  solution  of  cyanide 
of  potassium  is  added  to  the  precipitate  until  it  dissolves.  The 
coppering  solution  is  now  complete :  it  is  of  a  light  yellow  color, 
and  is  well  adapted  for  ordinary  purposes.  The  loss  of  copper  u», 
however,  considerable,  being  about  one-fifth  of  the  whole. 

Second  Method. — A  coppering  solution  may  also  be  prepared  by 
adding  cyanide  of  potassium,  to 'oxide  of  copper,  or  to  carbonate 
of  copper,  until  it  is  dissolved.  But  these  solutions  are  objec- 
tionable, the  latter  especially  so,  as  it  contains  a  great  quantity  of 
carbonate  of  potash,  formed  from  the  mutual  decomposition  of  the 
carbonate  of  copper  and  cyanide  of  potassium,  and  the  carbonate 
37 


573  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

of  potash  deteriorates  the  solution ;  the  former  leaves  potash  in 
the  solution,  but  this  is  not  so  bad  as  the  carbonate  of  potash. 

Third  Method. — The  method  we  have  adopted  in  manufacturing 
purposes  is  as  follows  : — To  a  solution  of  sulphate  of  copper,  we 
add  a  solution  of  ferrocyanide  of  potassium,  so  long  as  a  precipi- 
tate continues  to  be  formed:  this  is  allowed  to  settle,  and  the  clear 
liquor  being  decanted,  the  vessel  is  filled  with  water,  and  when 
the  precipitate  settles,  the  liquor  is  again  decanted,  and  we  con- 
tinue to  repeat  these  washings  until  the  sulphate  of  potash  is 
washed  quite  out.  This  is  known  by»adding  a  little  chloride  of 
barium  to  a  small  quantity  of  the  washings,  and  when  there  is  no 
white  precipitate  formed  by  this  test,  the  precipitate  is  sufficiently 
washed.  A  solution  of  cyanide  of  potassium  is  now  added  to  this 
precipitate  until  it  is  dissolved,  during  Which  process  the  solution 
becomes  warm  by  the  chemical  reaction  that  takes  place.  The 
solution  is  filtered,  and  allowed  to  repose  all  night.  If  the  solu- 
tion of  cyanide  of  potassium  that  is  used  is  strong,  the  greater 
portion  of  the  ferrocyanide  of  potassium  crystallizes  in  the  solu- 
tion, and  may  be  collected  and  preserved  for  use  again.  If  the 
solution  of  cyanide  of  potassium  used  to  dissolve  the  precipitate  is 
dilute,  it  will  be  necessary  to  condense  the  liquor  by  evaporation, 
to  obtain  the  yellow  prussiate  in  crystals ;  the  remaining  solution 
is  the  coppering  solution.  Should  it  not  be  convenient  to  separate 
the  yellow  prussiate  by  crystallization,  the  presence  of  that  salt  in 
the  solution  does  not  deteriorate  it,  nor  interfere  with  its  power  of 
depositing  copper. 

PECULIARITIES  IN  WORKING  CYANIDE  OF  COPPER  SOLUTION. — 
The  true  composition  of  the  salts  thus  formed  by  copper  and 
cyanide  of  potassium  has  not  yet  been  determined,  being  both 
various  and  complicated,  but  their  relations  to  the  battery  and 
electrolyzation  are  peculiar.  The  solution  must  be  worked  at  a 
heat  of  not  less  than  from  150°  to  200°  Fahrenheit.  All  other 
solutions  we  have  tried  follow  the  laws  laid  down  by  Spencer  and 
Smee,  namely,  that  if  the  electricity  is  so  strong  as  to  cause  gas  to 
be  evolved  at  the  electrode,  the  metal  will  be  deposited  in  a  sandy 
or  powdered  state ;  but  the  solution  of  cyanide  of  copper  and  pot- 
assium is  an  exception  to  these  laws,  and  there  is  no  reguline  de- 
posit obtained  unless  gas  is  freely  evolved  from  the  surface  of  the 
article  upon  which  the  deposit  is  taking  place.  This  necessitates 
the  use  of  batteries  of  several  pairs  intensity,  varying  from  five  to 
nine  pairs  of  Wollaston's  battery,  according  to  the  heat  and  the 
state  of  the  solution. 

As  this  solution  is  used  hot,  a  considerable  evaporation  takes 
place,  which  requires  that  additions  be  made  to  the  solution  from 
time  to  time.  If  water  alone  is  used  for  this  purpose,  it  will  pre- 
cipitate a  great  quantity  of  copper  as  a  white  powder,  but  this  is 
prevented  by  dissolving  a  little  cyanide  of  potassium  in  the  water 
at  the  rate  of  about  four  ounces  to  the  gallon.  The  vessels  used 
in  factories  for  this  solution  are  generally  of  copper,  which  are 


COATING   OF   IRON   WITH   COPPER.  579 

heated  over  a  flue,  or  on  a  sand-bath — the  vessel  itself  serving  as 
the  positive  electrode  of  the  battery ;  but  any  vessel  will  suit  if  a 
copper  electrode  is  employed,  when  the  vessel  is  not  of  copper. 

PREPARATION  OF  IRON  FOR  COATING  WITH  COPPER.— When  it 
is  required  to  cove^  an  iron  article  with  copper,  it  is  first  steeped 
in  hot  caustic  potash  or  soda,  to  remove  any  grease  or  oil.  Being 
washed  from  that,  it  is  placed  for  a  short  time  in  dilute  sulphuric 
acid,  consisting  of  about  one  part  of  acid  to  sixteen  parts  of  water, 
which  removes  any  oxide  that  may  exist.  It  is  then  washed  in 
water,  and  scoured  with  sand  till  the  surface  is  perfectly  clean,  and 
finally  attached  to  the  battery,  and  immersed  in  the  cyanide  solu- 
tion. All  this  must  be  done  with  despatch,  so  as  to  prevent  the 
iron  from  combining  with  oxygen.  An  immersion  of  five  minutes 
duration  in  the  cyanide  solution  is  sufficient  to  deposit  upon  the 
iron  a  film  of  copper.  But  it  is  necessary  to  the  complete  protec- 
tion of  the  iron,  that  it  should  have  a  considerable  thick  coating : 
and,  as  the  cyanide  process  is  expensive,  it  is  preferable,  when 
the  iron  has  received  a  film  of  copper  by  the  cyanide  solution,  to 
take  it  out,  wash  it  in  water,  and  attach  it  to  a  single  cell  or  weak 
battery,  and  put  it  into  a  solution  of  sulphate  of  copper.  If  there 
is  any  part  not  sufficiently  covered  with  copper  by  the  cyanide 
solution,  the  sulphate  will  make  these  parts  of  a  dark  color,  which 
a  touch  of  the  finger  will  remove.  When  such  is  the  case,  the 
article  must  be  taken  out,  scoured,  and  put  again  into  the  cyanide 
solution  till  perfectly  covered.  A  little  practice  will  render  this 
very  easy.  The  sulphate  solution  for  covering  iron  should  be  pre- 
pared by  adding  to  it  by  degrees  a  little  caustic  soda,  so  long  as 
the  precipitate  formed  is  re-dissolved.  This  neutralizes  a  great 
portion  of  the  sulphuric  acid,  and  thus  the  iron  is  not  so  readily 
acted  upon. 

EFFECTS  OF  CONDUCTING  POWER  IN  SOLUTIONS  AND  METALS. — 
In  covering  iron,  platinum,  or  such  comparatively  bad-conducting 
metals,  with  other  metals  that  are  good  conductors,  or  the  solutions 
of  which  are  good  conductors,  the  property  of  conduction  in  rela- 
tion to  the  solution  is  beautifully  illustrated.  If  we  take  a  copper 
wire,  say  8  or  10  feet  long,  one  end  of  which  is  attached  to  the 
zinc  of  a  battery,  and  laid  parallel  with  the  positive  electrode  into 
a  solution  for  the  purpose  of  receiving  a  deposit,  it  will  be  found 
that  the  greatest  amount  of  deposit  has  taken  place  at  the  end 
furthest  from  the  battery  :  but  if  an  iron  or  platinum  wire  be  sub- 
stituted for  the  copper  one,  the  contrary  result  will  take  place ;  for 
the  end  furthest  from  the  battery  will  be  the  last  to  receive  the 
coating,  and  will  have  the  least  quantity  of  metal  deposited  upon 
it.  If  the  copper  wire  was  30  feet  long,  little  alteration  would  be 
seen  in  the  deposit;  but  upon  an  iron  or  platinum  wire  of  that 
length  the  deposit  proceeds  only  a  certain  distance,  and  no  deposit 
will  take  place  on  the  end  furthest  from  the  battery  until  the  cur- 
rent has  passed  a  considerable  time,  after  which  the  deposit  is 
observed  to  advance  gradually.  The  copper  as  it  becomes  deposited 


580  THE   PRACTICAL   METAL  -WORKER'S  ASSISTANT. 

on  the  iron  acts  as  a  conductor,  transmitting  the  deposit  further 
onwards  to  its  final  point,  as  well  as  adding  to  the  deposition  already 
effected  upon  the  iron.  The  length  of  deposit  that  would  be  formed 
on  the  first  immersion  of  the  wire  depends  upon  the  conducting 
power  of  the  solution ;  for,  as  already  stated,  solutions  vary  in  this 
property  as  well  as  metals.  We  have  found  that  a  few  feet  of  iron 
wire  offer  a  greater  resistance  to  the  passage  of  the  current  than 
the  solution  between  the  iron  wire  and  the  positive  electrode,  which 
is  only  about  2  or  3  inches ;  but  their  exact  relations  to  each  other 
we  have  not  yet  had  an  opportunity  of  investigating. 

Under  these  circumstances,  it  may  be  asked,  why  not  increase 
the  intensity  of  the  battery,  and  so  force  it  along  the  wire  ?  But 
this,  as  will  be  apparent,  can  only  be  done  within  certain  limits ; 
for  by  increasing  the  intensity  of  the  battery  it  may  be  rendered 
too  strong  for  the  solution  near  the  battery,  and  thus  a  sandy 
deposit  will  be  given  at  the  one  end  and  none  at  the  other.  The 
electro-metallurgist,  when  coating  long  rods  of  iron  wire  with  any 
metal,  has  to  make  connections  with  the  battery  every  few  feet. 
The  wire  is  generally  coiled  up  in  the  form  of  a  cork-screw,  and 
suspended  by  copper  wires.  We  have  found  it  very  convenient  to 
coil  it  upon  a  reel,  having  its  armatures  tipped  with  copper,  and 
connected  with  the  battery.  This  plan  insures  a  regular  coating, 
but  the  position  of  the  wire  requires  to  be  changed  during  the 
operation,  otherwise  the  parts  which  press  upon  the  arms  of  the 
reel  will  be  left  without  deposit. 

ILLUSTRATION  OF  CONDUCTION. — As  an  illustration  of  the  prop- 
erty of  conduction,  we  mention  the  following  circumstance : — Hav- 
ing a  large  iron  shaft,  or  rod,  about  12  feet  long  and  3  inches  aver- 
age diameter,  to  cover  with  copper,  we  had  it  properly  cleaned, 
placed  in  a  hot  solution  of  cyanide  of  copper  and  potassium,  and 
surrounded  by  sheets  of  copper  as  a  positive  electrode.  Two  bat- 
teries of  7  pairs  intensity  were  attached,  one  at  each  end  of  the 
shaft ;  but,  by  an  oversight,  one  of  the  batteries  was  not  properly 
connected,  the  copper  terminal  of  the  battery  having  been  attached 
to  the  shaft.  Had  the  shaft  been  of  copper,  the  one  battery  would 
have  neutralized  the  other,  so  that  there  would  not  have  been  any  • 
deposit^;  or,  had  the  one  battery  been  stronger  than  the  other,  there 
would  have  been  a  current  and  deposit  equal  to  the  excess  of  power 
of  the  one  over  the  other.  But,  under  the  stated  circumstances,  a 
different  result  was  obtained.  After  the  batteries  had  beun  in 
action  two  hours,  we  found  that  a  beautiful  copper  coating  was  im- 
parted to  that  half  of  the  shaft  which  extended  from  the  point  prop- 
erly connected,  while  the  other  half  was  quite  bare— no  deposit 
having  taken  place  upon  it :  but  a  deposit  had  been  made  upon  the 
copper  electrode  opposite  this  non-affected  half.  The  batteries  did 
not  (as  we  could  perceive)  affect  one  another,  except  that  the  one 
improperly  connected  prevented  the  deposit  effected  by  the  other 
proceeding  further  than  the  half  length  of  the  shaft;  but  it  made  the 
deposit  obtained  more  perfect  than  would  have  been  the  case  had 
there  been  only  one  battery  at  one  end. 


COATING  OF  IRON  WITH  OTHER  METALS.        581 

In  this  instance,  the  distance  of  the  shaft  from  the  electrode  was 
6  inches,  so  that  the  resistance  of  6  feet  of  the  iron  was  more  than 
6  inches  of  the  solution;  hence  the  influence  of  the  contra-acting 
battery  could  not  reach  further:  or  if  any  power  passed  further  it 
was  neutralized  by  the  other  battery — which  we  are  inclined  to 
think  did  not  take  place — as  the  amount  or  thickness  of  deposit 
upon  the  one  half  was  fully  more  than  we  would  have  anticipated 
upon  the  whole,  had  the  batteries  been  properly  connected. 

NON-ADHERENCE  OF  DEPOSIT.— Objections  have  been  made  to 
covering  iron  with  copper  for  its  protection,  from  an  impression 
that  the  copper  will  not  adhere  to  the  iron ;  but  if  the  operation  is 
carefully  performed  the  copper  will  adhere ;  when  it  does  not,  it 
will  generally  be  found  that  it  is  the  copper  deposited  from  the  sul- 
phate which  loosens  from  the  copper  deposited  from  the  cyanide — 
occasioned  no  doubt,  by  the  article  not  having  been  sufficiently 
washed  from  the  cyanide  solution,  and  thus  having  a  thin  film  of 
cyanide  of  copper  precipitated  upon  the  surface,  which  prevents 
the  adhesion  of  the  after  deposit.  Or,  as  it  happens  sometimes, 
that  the  cyanide  of  copper  solution  has  not  much  free  cyanide  of 
potassium,  and,  consequently  on  putting  the  article  into  water,  the 
cyanide  of  copper  is  decomposed  by  the  water,  and  precipitated 
upon  the  surface.  If  a  little  cyanide  of  potassium  is  dissolved  in 
the  first  water  used  for  washing  out  the  depositing  solution,  this 
will  be  prevented. 

We  have  repeatedly  deposited  copper  upon  iron  wire,  and  after- 
wards had  it  drawn  out  to  twice  its  original  length  without  the 
copper  striping  off;  but,  as  the  copper  becomes  hard  and  brittle,  it 
is  liable  to  break  if  the  wire  is  much  bent,  and  if  it  be  made  red 
hot,  to  anneal  or  soften  it,  the  copper  will  oxidize,  and  if  the  coat- 
ing is  thin,  the  iron  will  be  left  bare  in  some  places.  "We  have 
seen  iron  bolts,  covered  with  copper,  driven  through  17  inch  wood, 
and  nails  of  all  sizes  subjected  to  rough  work,  without  the  deposit 
being  injured.  Some  iron  work  coated  in  1842,  and  exposed  to 
the  atmosphere,  remains  in  good  condition  still.  These  remarks  are 
also  applicable  to  iron  covered  with  zinc.  The  coating  of  iron  with 
copper  has  been  tried  in  a  great  variety  of  ways  for  large  opera- 
tions, but  in  general  these  trials  have,  commercially,  ended  unsuccess- 
fully ;  the  labor  and  cost  is  greater  than  the  advantages  sought  will 
warrant  for  ordinary  purposes.  Many  years  ago  trials  were  made  to 
cover  cast-iron  with  copper,  and  then  gild  or  plate  for  ornamental 
use,  but  only  with  partial  success.  More  recently,  however,  a  patent 
has  been  taken  out  for  the  same  purpose,  and  which,  being  one  of 
these  applications  that  would  be  useful  in  beautifying  and  improv- 
ing the  taste  of  the  community,  we  give  an  abstract  of  the  specifi- 
tion  as  follows :  % 

COATING  CAST-IRON  WITH  OTHER  METALS.— "Mr. W.Newton  (for 
a  correspondent)  has  patented  the  coating  cast-iron  permanently  with 
copper,  by  depositing  the  copper  by  galvanic  action,  from  a  solu- 
tion prepared  by  first  taking  a  saturated  solution  of  sulphate  of 


582  THE   PEACTICAL   METAL-WORKER^   ASSISTANT. 

copper  in  water  and  precipitating  with  carbonate  of  potash,  and 
then  re-dissolving  in  cyanide  of  potassium,  whether  the  copper  be 
deposited  directly  on  the  surface  of  the  cast  iron,  or  on  zinc  previ- 
ously deposited  thereon.  The  second  part  of  this  invention  con- 
sists of  coating  cast-iron  with  the  alloy  of  copper  called  brass,  by 
first  coating  the  cast-iron  with  copper,  or  zinc,  or  both,  and  then 
depositing  the  brass  thereon,  by  galvanic  action,  from  a  solution 
formed  by  mixing  with  the  solution  of  copper  employed  in  the  first 
part  of  the  invention,  a  solution  of  zinc  prepared  in  substantially 
the  same  manner.  The  iron  articles  thus  coated,  may  be  subse- 
quently coated  with  gold  or  silver,  so  as  to  give  them  the  appear- 
ance of  these  latter  metals.  The  articles  of  cast-iron  to  be  coated 
or  plated  are  first  to  be  cleansed  by  what  is  known  as  the  'pick- 
ling' process,  with  dilute  sulphuric  acid,  and  then  'scratch- brushed,' 
as  it  is  termed,  to  free  the  surface  from  scale,  sand,  and  other  foreign 
substances  which  may  not  have  been  removed  by  the  acid ;  and 
after  this  the  castings  are  to  be  immersed  in  dilute  nitro-muriatic 
acid.  Any  other  mode  of  thoroughly  cleansing  the  surface  may 
be  substituted  for  that  above  indicated.  A  solution  of  zinc  is  then 
prepared  in  the  following  manner : — Dissolve  the  sulphate  of  zinc 
in  water  until  the  water  is  saturated,  and  precipitate  by  means  of 
prussiate  of  potash.  The  precipitate  is  then  collected  in  a  filter, 
and  re-dissolved  in  cyanide  of  potassium.  This  constitutes  solu- 
tion number  one.  A  solution  of  copper  is  then  prepared  in  the 
same  manner,  by  dissolving  sulphate  of  copper  in  water,  and  pre- 
cipitating with  car.bonate  of  potash :  this  precipitate  is  dissolved  in 
cyanide  of  potassium,  and  is  called  the  second  or  copper  solution. 
The  third,  or  what  may  be  termed  the  brass  solution,  is  then  pre- 
pared by  mixing  together  the  first  or  zinc  solution  with  the  second 
or  copper  solution,  in  such  proportions  as  to  produce  the  shade  of 
color  required — increasing  the  proportional  quantity  of  the  one  or 
the  other  at  the  discretion  of  the  operator.  The  iron  castings  hav- 
ing been  thoroughly  cleansed,  are  first  immersed  in  the  first  or 
zinc  solution,  and  the  galvanic  battery  applied  in  the  usual  man- 
ner of  electrotyping  and  continued  until  the  required  thick- 
ness of  zinc  is  deposited  on  the  surface  of  and  caused  to  unite 
with  the  surface  of  the  cast-iron,  which  is  a  carbonate  of  iron. 
The  castings  thus  coated  or  plated  with  zinc,  are  then  to  be 
immersed  in  the  second  or  copper  solution,  and  the  galvanic  bat- 
tery applied,  as  with  the  first  or  zinc  solution,  and  continued  until 
the  required  thickness  of  copper  shall  have  been  deposited.  In 
this  way  it  will  be  found  that  the  copper  coating  has  become 
thoroughly  attached  to  the  zinc,  and  the  zinc  to  the  iron,  so  that 
they  cannot  be  removed  except  by  filing  or  cutting,  as  in  the  case 
of  a  solid  mass  of  copper  ;^o  that  articles,  of  whatever  form  desired, 
which  can  be  made  of  cast-iron — that  is,  of  carbonate  of  iron — can 
be  coated  with  copper,  so  as  to  answer  nearly  if  not  all  the  pur- 
poses to  which  they  could  be  applied  if  made  of  solid  copper;  thus 
greatly  economizing  the  cost.  After  the  surface  of  cast-iroD  has 


COATING   OF   IRON   WITH   ZINC.  583 

been  coated  with  zinc,  or  with  copper,  or  with  zinc  and  then  with 
copper,  which  latter  is  much  the  best,  if  it  be  desired  to  coat  it 
with  brass,  it  is  to  be  immersed  in  the  third  or  brass  solution,  and 
the  galvanic  battery  applied,  until  the  required  thickness  shall 
have  been  deposited.  In  doing  this  it  is  important  that  the  posi- 
tive pole  of  the  battery  should  be  irfade  of  brass,  and  as  nearly  as 
practicable  of  the  shade  of  the  brass  to  be  deposited;  for  if  a  cop- 
per pole  be  applied,  it  will  deposit  in  excess  the  copper  portion  of 
the  solution.  If  desired,  the  brass  can  be  deposited  on  the  coat- 
ing of  zinc  instead  of  the  coating  of  copper ;  but  it  will  be  found 
decidedly  better  to  deposit  the  brass  on  the  coating  of  copper, 
whether  the  copper  be  deposited  directly  on  the  cast-iron  or  on  a 
coating  of  zinc,  although  the  latter  is  the  best.  In  this  way  articles 
are  produced,  having  all  the  appearance,  and  answering  nearly  if 
not  all  the  same  purposes  as  if  made  entirely  of  brass,  and  at  much 
less  cost.  The  cast-iron  being  thus  coated  with  brass,  the  surface 
may  be  bronzed  in  the  usual  and  well-known  manner  of  bronzing 
brass ;  and  as  the  process  of  bronzing  on  brass  and  copper  is  well 
known,  it  will  be  unnecessary  to  give  a  detailed  description  of  it. 
The  surface  of  the  cast-iron  being  thus  coated  with  brass,  or  with 
copper,  can  then  be  coated  effectually  with  silver  or  gold  in  any  of 
the  well  known  modes  of  coating  brass  or  copper  with  those  fine 
metals ;  it  will  not,  however,  be  necessary  to  give  the  details  of 
such  mode  or  modes,  as  they  are  well  known  in  the  arts.  The 
patentee  remarks  that  it  will  be  found  better  to  deposit  the  silver 
or  gold  on  the  brass  coating  than  on  the  copper  coating,  on  account 
of  the  color — particularly  when,  from  reasons  of  economy,  it  is 
desired  to  make  the  coating  of  fine  metal  very  thin.  The  patentee 
claims  the  process  herein  described,  or  any  mere  modification 
thereof,  for  coating  cast-iron  (carbonate  of  iron)  with  copper,  by 
causing  the  copper,  from  a  solution  such  as  above  described,  to 
deposit,  by  galvanic  action,  directly  on  the  surface  of  the  cast-iron, 
or  on  the  zinc  previously  deposited  thereon,  as  set  forth.  And 
also  the  process  herein  described,  or  any  mere  modification  thereof, 
for  coating  cast-iron  with  the  alloy  of  copper,  known  as  brass,  by 
causing  the  brass,  from  a  solution  such  as  above  described,  to 
deposit,  by  galvanic  action,  on  to  the  surface  of  the  cast-iron,  pre- 
viously coated  with  zinc,  or  copper,  or  both,  as  specified,." 

COATING  OF  IRON  WITH  ZINC. — In  covering  iron  with  zinc,  the  pre- 
cautions necessary  for  copper  are  not  required:  zinc  being  the  posi- 
tive metal,  acids  have  a  stronger  affinity  for  it  than  for  iron,  and 
therefore  an  acid  solution  may  be  used.  The  one  generally  used 
is  the  sulphate. 

SULPHATE  OF  ZINC. — Zino  dissolves  easily  in  sulphuric  acid,  and 
the  solution  by  evaporation  yields  crystals  of  sulphate  of  zinc ;  but 
as  the  salt  is  very  cheap  and  abundant  in  the  market,  it  is  more 
convenient  and  economical  to  buy  than  to  make  it.  The  solution 
for  depositing  is  made  by  dissolving  2  Ibs  of  the  crystallized  salt 
in  one  gallon  of  water.  The  single  cell  process  cannot  be  used 


584  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

advantageously  with  this  solution.  A  separate  battery  is  necessary, 
and  a  zinc  positive  electrode.  The  metal  is  very  easily  deposited 
one  or  two  pairs  of  Wollaston's  battery  being  sufficient  for  coat- 
ing small  articles. 

Zinc  may  be  deposited  upon  black-leaded  surfaces  in  the  same 
manner  as  copper ;  but,  unless  more  than  ordinary  precautions  are 
observed,  an  article  formed  in  this  manner  is  so  brittle  that  it  can 
hardly  be  handled  without  breaking,  from  its  crystalline  character. 
When  the  deposition  upon  black-lead  is  attempted,  the  best  method 
is  to  have  the  solution  saturated  with  salt,  employing  a  battery  of 
six  or  seven  pairs  of  plates,  and  keeping  the  articles  on  which  the 
deposit  is  taking  place  constantly  in  motion. 

The  use  of  cyanide  of  zinc  has  been  recommended,  but  for  what  good 
reason  it  is  hard  to  know.  It  is  unnecessary,  and  its  use  presents  great 
practical  difficulties.  The  positive  electrode  becomes  coated,  after  a 
few  minutes  working,  with  a  white  pasty  matter  which  prevents 
further  action  and  stops  the  current.  Some  of  this  white  coating 
collected,  washed,  and  dried  in  the  air,  gave  by  analysis, 

Oxide  of  zinc 51*3 

Cyanogen 1'7 

Iron tirace 

Potash 2-3 

Carbonic  acid 27*8 

Matter  insoluble  in  HC1. .     .     .  2'5 

Water 14'8 

*  '    -i** 

1004 

The  zinc  is  converted  into  carbonate  of  zinc :  the  potash  is  com- 
bined with  the  cyanogen  as  cyanide  of  potassium. 

USE  OF  ZINC  COATING. — The  principal  application  of  zinc  is 
upon  iron,  to  protect  it  from  corrosion,  which  it  does,  not  only  as  a 
coating,  but,  from  its  more  electro-positive  character,  it  protects  it 
by  a  galvanic  influence.  The  voltaic  influence  of  zinc  for  protect- 
ing iron  is  a  subject  that  has  occupied  the  attention  of  practical 
men  for  a  long  time ;  it  is  one  of  high  importance :  nevertheless 
there  seems  yet  a  great  deficiency  in  our  knowledge  of  the  extent 
of  this  influence,  and  how  and  when  it  is  effective. 

Upon  this  subject,  Professor  Faraday,  in  the  Report  of  the  Har- 
bors of  Eefuge  Commissioners,  states,  "Zinced  iron  would  no  doubt 
resist  the  action  of  sea- water  so  long  as  the  surface  was  covered 
with  zinc,  or  even  when  partially  denuded  of  that  metal :  but  zinc 
dissolves  rapidly  in  sea- water,  and  after  it  is  gone,  the  iron  would 
follow. 

"As  to  voltaic  protection,  it  has  often  struck  me  that  the  cast- 
iron  piles  proposed  for  lighthouses,  or  beacons,  might  be  protected 
by  zinc  in  the  same  manner  as  Davy  proposed  to  protect  copper  by 
iron;  but  there  is  no  doubt  the  corrosion  of  the  zinc  would  be  rapid. 
If  not  found  too  expensive,  the  object  would  be  to  apply  the  zinc 


INFLUENCE   OF   GALVANISM   IN   PROTECTING.  585 

protectors  in  a  place  where  they  could  be  examined  often,  and 
replaced  when  rendered  ineffective.  In  this  manner  I  have  little 
doubt  that  iron  would  be  protected  in  sea-water." 

INFLUENCE  OF  GALVANISM  IN  PROTECTING  METALS  FROM  DE- 
STRUCTION BY  OXIDATION  AND  SOLUTION. — The  galvanic  influence 
of  one  metal  in  protecting  another  is  in  relation  to  their  negative 
and  positive  qualities  together  with  their  conducting  powers  (p. 
515).  Their  relations  in  sea-water  are — silver,  copper,  bismuth, 
antimony,  iron,  tin,  lead,  cadmium,  zinc;  the  first  the  most  negative, 
the  last  the  most  positive  in  the  series.  So  that,  according  to  this 
scale,  the  further  apart  the  metals  may  be  which  are  selected  for 
experiment,  the  more  decided  will  be  the  power  of  the  positive  to 
protect  the  negative.  Copper  and  zinc  operate  more  strongly 
together  than  iron  and  zinc. 

A  metal  that  is  insoluble  when  placed  singly  in  a  fluid,  may  be 
made  soluble  by  connection  with  a  relatively  negative  metal  placed 
in  the  same  fluid.  For  example,  pure  zinc  put  into  muriatic  acid 
is  unaffected,  but  when  connected  with  copper  in  the  same  fluid  it 
is  rapidly  operated  upon.  Or  a  metal  may  be  soluble  in  a  fluid 
alone,  but  may  be  rendered  insoluble  by  connection  with  a  relatively 
positive  metal  which  undergoes  decomposition  instead.  Thus :  cop- 
per is  dissolved  in  sea-water  when  alone,  but  when  a  piece  of  zinc 
is  connected  with  it,  the  copper  is  unaffected.  This  last  effect  is 
the  substance  of  Davy's  method  of  protection  alluded  to  by  Dr. 
Faraday,  in  applying  the  principle  of  which  it  is  necessary  to  take 
into  consideration, 

1st,  The  amount  and  power  of  electricity  generated  by  the  con- 
nected metals  in  the  same  fluid ;  and 

2d,  The  conducting  power  of  the  metal  which  is  being  pro- 
tected. 

1st.  The  amount  and  power  of  the  electricity  evolved  is  in  pro- 
portion to  the  difference  of  the  relative  negative  and  positive  con- 
dition of  the  metals  employed.  The  more  negative  the  coated  metal 
is,  the  less  it  requires  protection,  although  its  powers  of  protection 
are  the  greatest.  And  the  more  positive  the  coated  metal,  the  more 
liable  it  is  to  be  destroyed,  and  the  greater  the  amount  of  electricity 
required  to  protect  it ;  but  unfortunately  it  is  less  able  to  generate 
this  electricity  wlien  in  contact  with  another  metal.  Thus  these  two 
conditions  are  opposed  to  the  application  of  galvanic  influence  for 
protecting  iron. 

Suppose,  for  example,  that  4  square  inches  of  zinc,  in  connection 
with  4  square  feet  of  copper,  give  out  sufficient  electricity  to  pro- 
tect the  copper  from  sea-water,  it  will  be  found  that  to  obtain  the 
same  amount  of  electricity  by  iron  and  zinc,  2  square  feet  of  the 
latter  to  4  square  feet  of  the  former  are  required.*  Besides  which, 
the  same  quantity  of  electricity  that  protects  copper  will  not  pro- 

*  These  proportions,  given  in  round  numbers,  are  nearly  accurate  ;  but  they 
vary  according  to  the  kiud  of  iron,  the  state  of  the  water,  the  distance  of  the 
metals,  etc. 


586  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

tect  iron;  nor  will  any  quantity  of  zinc  protect  iron  from  corrosion 
in  sea- water — even  a  bar  of  iron  placed  in  a  zinc  vessel  filled  with 
sea- water  is  not  completely  protected. 

2d.  The  conducting  power  of  the  negative  or  protected  metal  sub- 
Fig.  580.  jected   to   submarine   im- 
mersion is  a  subject  of  very 
great  importance.  Suppose 
a  piece  of  copper  and  a 

---_^  r~""*~— —- ~._  piece  of  zinc  be  connected 
••„,.„.„„,„:,;„•„,,„„..,,,.„ ^a  under  a  solution  —  say  a 
C  copper  bar  (c)  4  feet  long, 

with  a  piece  of  zinc  (z)  4  inches  in  length,  erected  on  one  end,  as  in 
the  annexed  sketch: 

The  conducting  power  of  the  copper  is  so  much  superior  to  that 
of  the  solution  that  the  whole  length  of  the  bar  will  become  in- 
stantly negative,  and  the  current  of  electricity  will  pass  to  and  from 
all  parts  of  the  bar  at  the  same  time  in  the  lines  &,&,&;  but  the  cur- 
rent will  be  more  active  towards  the  point  of  contact  than  towards 
the  distant  extremity — the  resistance  of  the  solution  being  less  in  pro 
portion  to  the  proximity  of  the  metals.  But  if  a  bar  of  iron,  and  a 
piece  of  zinc  as  a  protector,  be  placed  in  the  same  circumstances, 
the  phenomena  assume  quite  a  different  aspect:  the  conducting 
power  of  iron  being  much  less  than  that  of  copper,  the  distant  ex- 
tremity will  not  be  affected  by  the  electric  current,  which  will  find 
a  more  easy  passage,  as  indicated  by  the  dotted  lines  e,  e,  e.  beyond 
which  the  electric  effort  ceases ;  and  even  in  that  portion  of  the  bar 
which  is  under  the  influence  of  the  current,  the  part  nearest  the 
zinc  is  better  defended  than  those  parts  which  are  farther  dis- 
tant. This  partial  protection,  while  it  induces  a  negative  state  at 
the  near  end,  renders  the  other  end  more  positive.  Such  a  diver- 
sity of  condition  gives  rise  to  voltaic  action  between  the  two  ex- 
tremities of  the  bar,  and  the  result  is  the  destruction  of  the  far 
end.  In  all  cases  of  voltaic  protection  the  more  equal  the  influ- 
ence over  the  whole  surface  protected,  the  more  perfect  is  the  pro- 
tection. An  inequality  of  protection,  such  as  we  have  described, 
is  productive  of  numerous  evils.  It  is,  we  believe,  the  source  of 
many  of  the  injuries  occurring  in  our  day  to  copper  sheathing. 
One  part  of  a  sheet  becoming,  by  some  local  cause,  negative,  the 
other  parts  are  thus  rendered  positive ;  the  result  is,  that  upon  the 
borders  of  an  individual  sheet  either  overlapping  or  underlying  its 
neighboring  sheet,  an  electric  current  is  excited,  passing  through 
the  stratum  of  moisture  which  may  intervene,  and  the  ultimate 
effect  is  that  the  positive  edge  is  dissolved  as  effectually  as  if  cut 
by  a  knife.  The  evil  arising  in  one  place  may  be  so  contagious  as 
to  affect  a  whole  neighborhood — sometimes  the  whole  side  of  a 
ship's  bottom. 

In  fresh  water  iron  cannot  be  protected  any  length  of  time,  for 
the  zinc  coating  speedily  passes  into  a  blackish  substance,  which 
peels  off  and  exposes  the  iron  to  rust.  When  iron  is  simply  ex- 


ELECTRO -PLATING.  587 

posed  to  the  air,  a  good  coating  of  zinc  is  a  sure  protection.  "We 
have  seen  iron  of  various  qualities  coated  by  the  electro-processes 
and  exposed  to  the  atmosphere,  in  all  weathers,  for  several  years, 
without  being  more  affected  than  a  piece  of  zinc  would  be.  In 
spots  where  abrasion  has  taken  place  by  accident,  the  protecting 
power  of  the  zinc  is  lost,  and  the  iron  rusts  as  if  there  were  no  zinc 
present.  No  other  result,  however,  could  be  anticipated,  as  there 
can  be  no  electric  excitation  without  a  liquid  to  connect  the  two 
metals. 

The  iron  to  be  coated  by  zinc  is  to  be  cleaned  and  prepared  in 
the  same  manner  as  we  have  described  for  the  purpose  of  covering 
it  with  copper  (page  579). 


CHAPTER  XXX. 

ELECTRO-PLATING. 

THE  next  applications  of  the  electro-deposition  we  have  to 
notice  are  those  relating  to  silver  and  gold,  embracing  the  arts  of 
electro-plating  and  gilding — arts  which  are  gradually  revolutioniz- 
ing some  extensive  branches  of  manufacture,  having  the  same 
object  but  acting  by  a  different  means. 

To  MAKE  SILVER  SOLUTION. — The  solution  of  silver  used  for 
plating  consists  of  cyanide  of  silver  dissolved  in  cyanide  of  potas- 
sium which  may  be  prepared  in  various  ways.  We  shall  first  de- 
scribe some  of  the  preparations  most  in  use,  and  also  point  out 
practical  objections  which,  in  special  cases,  have  occurred  under  our 
own  observation,  not  omitting  to  specify  and  recommend  those 
methods  which  have  approved  themselves  to  us  as-  being  most 
simple  and  effective. 

The  method  generally  adopted  is  as  follows: — Metallic  silver  is 
dissolved  in  four  parts  of  nitric  acid,  diluted  with  one  part  of  water : 
the  diluted  acid  is  heated  in  a  vessel,  and  the  silver  is  added  by 
degrees.  The  operator  must  avoid  breathing  the  furnes  which 
ascend,  as  they  are  highly  deleterious.  The  metal  being  dissolved, 
the  solution  is  transferred  to  a  large  vessel,  and  diluted  with  water. 
To  this  is  added  a  solution  of  cyanide  of  potassium  so  long  as  a 
white  precipitate  is  formed.  This  precipitate  is  cyanide  of  silver, 
and  the  action  which  ensues  may  be  thus  represented : 

Substances  used:  Substances  prodded: 

Nitrate  of  silver  =  AgO,  NO5    Nitrate  of  potash  =  KO,  NO5 


Cyanide  of  potassium  =  KCy 


Cyanide  of  silver  =AgCy 


AgO,NO'+KCy=KO,  NO'+AgCy 

The  propriety  of  diluting  the  nitrate  of  silver  before  precipitat- 
ing by  the  cyanide  of  potassium  arises  from  the  fact,  that  the  salts 
of  potash  and  soda  (such  as  the  nitrates,  chlorides  and  sulphates), 


588  THE  PRACTICAL  METAL-WORKER'S  ASSISTANT. 

when  in  strong  solution,  dissolve  small  quantities  of  the  silver  salt, 
and  thus  cause  a  loss,  which  is  prevented  b j  previous  dilution  with 
water. 

When  the  precipitate  of  cyanide  of  silver  has  settled,  the  clear 
solution  is  carefully  decanted,  and  the  vessel  filled  up  with  water, 
which  is  again  decanted  as  soon  as  the  precipitate  has  settled.  This 
process  is  to  be  repeated  three  or  four  times,  so  as  effectually  to 
wash  out  the  soluble  salts.  "When  properly  washed,  a  solution  of 
cyanide  of  potassium  is  added  to  the  precipitate,  until  it  is  all  dis- 
solved. The  resulting  solution  constitutes  the  cyanide  of  potassium 
and  silver,  and  forms  the  plating  solution.  It  ought  to  be  filtered 
previous  to  using,  as  there  is  always  formed  a  black  sediment,  com- 
posed of  iron,  silver,  and  cyanogen,  which,  if  left  in  the  solution, 
would  fall  upon  the  surface  of  the  article  receiving  the  deposit,  and 
make  it  rough.  The  sediment,  however,  must  not  be  thrown  away, 
as  it  contains  silver.  The  cyanide  of  potassium,  used  to  dissolve 
the  cyanide  of  silver,  may  be  so  diluted  that  the  plating  solution, 
when  formed,  shall  contain  one  ounce  of  silver  in  the  gallon :  of 
course  the  proportion  of  silver  may  be  larger  or  smaller,  but  that 
given  is  what  we  consider  best  for  plating. 

In  dissolving  100  ounces  of  silver,  the  following  proportions  of 
each  ingredient  are  those  which  we  have  found  in  practice  to  be  the 
best.  Take  7  pounds  of  the  best  nitric  acid*  and  61  ounces  of 
cyanide  of  potassium,  of  the  average  quality  described  at  page  576 ; 
this  quantity  will  precipitate  the  100  ounces  of  silver  dissolved  in  the 
acid  solution.  After  this  is  washed,  take  62  ounces  more  of  cyanide 
of  potassium,  the  solution  of  which  will  dissolve  the  precipitate : 
this  being  done,  the  plating  solution  is  then  formed.  Of  course, 
these  proportions  will  vary  according  to  the  difference  in  the  quality 
of  the  materials ;  but  they  will  serve  to  give  an  idea  of  the  cost  of 
the  silver  solution  prepared  in  this  manner. 

CYANIDE  OF  SILVER  DISSOLVED  IN  YELLOW  PRUSSIATE  OF  POT- 
ASH.— "We  have  occasionally  dissolved  the  cyanide  of  silver  by 
yellow  prussiate  of  potash,  three  pounds  of  which  are  required  to 
dissolve  one  ounce  of  silver.  This  forms  an  excellent  plating  solu- 
tion, and  yields  a  beautiful  surface  of  silver.  It  must  have  a  weak 
battery  power,  and  consequently  the  silver  is  very  soft.  The  posi- 
tive electrode  does  not  dissolve  in  this  solution :  there  is  formed 
upon  its  surface  a  white  scaly  crust,  which  drops  off  and  falls  to 
the  bottom ;  and  the  solution  soon  becomes  exhausted  of  silver. 

SOLUTION  MADE  WITH  OXIDE  OF  SILVER. — It  has  been  recom- 
mended to  dissolve  the  oxide  of  silver  in  cyanide  of  potassium, 
which  forms  a  solution  of  cyanide  of  potassium  and  silver;  but  this 
preparation  is  less  economical,  because  the  materials  used  in  con- 
verting the  silver  into  an  oxide  are  lost :  it  requires  the  same  amount 

*  The  nitric  acid  must  be  free  from  hydrochloric  (muriatic)  acid :  to  a  small 
quantity  of  the  acid  add  a  few  drops  of  solution  of  nitrate  of  silver;  if  it  gives  a 
milky  white  precipitate,  it  contains  muriatic  acid,  and  should  be  rejected. 


ELECTRO-PLATING.  589 

of  cyanide  of  potassium  as  the  process  just  described,  and  brings, 
moreover,  an  equivalent  of  potash  into  the  solution,  which  is  a  dis- 
advantage. The  following  diagram  shows  the  reactions  that  occur: 

Substances  used:  Substances  produced: 


Potash  =  KG 

Cyanide  of  silver  f      -^^      .    ~ 
and  potassium  [  =^Cy,  AgCy 


Oxide  of  silver  =  AgO 

Cyanide  of  potassium  =  KCy 
Cyanide  of  potassium  =  KCy 

AgO+2  KCy  =  KG  +  KG,  AgCy. 

SOLUTION  MADE  WITH  CHLORIDE  OF  SILVER. — The  nitrate  of 
silver  may  also  be  precipitated  by  adding  a  solution  of  common 
salt  to  it,  and  treating  it  in  the  same  way  as  described  for  precipi- 
tation by  cyanide  of  potassium :  this  would  form  chloride  of  silver, 
which  may  be  dissolved  in  cyanide  of  potassium,  thus  forming  the 
silver  solution.  But  the  objection  urged  against  the  use  of  oxide 
of  silver  is  equally  applicable  in  the  case  of  chloride  ;  and  much 
greater  care  is  required  in  precipitating  large  quantities  and  strong 
solutions  of  silver  by  common  salt,  than  by  cyanide  of  potassium, 
the  chloride  of  silver  being  more  soluble  in  the  salts  of  the  alka- 
lies— as  the  nitrates,  chlorides,  and  sulphates — than  cyanide  of 
silver  is ;  and  there  is  therefore  great  liability  to  loss  by  this 
process,  in  which  we  have  not  the  redeeming  quality  of  a  saving 
of  materials,  as  the  following  diagram  will  show : 

Substances  used:  Substances  produced: 


Chloride  of  potassium     =  KCI 
Cyanide  of  silver 
and  potassium 


Chloride  of  silver         =  AgCl 
Cyanide  of  potassium  =  KCy 
i  Gyanide  of  potassium  =  KCy 

rv  ';i!       AgCl+2  KCy  =  KCI -f  KCy,  AgCy." 

Thus,  we  observe,  that  the  action  taking  place  is  not  mere  solu- 
tion, but  decomposition ;  which  upon  one  hundred  ounces  of  silver 
in  this  preparation  produces  an  impurity  of  seventy  ounces  of 
chloride  of  potassium,  which,  although  not  very  injurious  to  the 
solution,  would  be  much  better  away. 

THE  BEST  METHOD  OF  MAKING  SILVER  SOLUTION. — The  best 
and  cheapest  method  of  making  up  the  silver  solution  is  by  the 
battery,  which  saves  all  expense  of  acids  and  the  labor  of  precipi- 
tation. This  is  effected  by  taking  advantage  of  the  principle  of 
non-transfer  of  metal  in  electrolytes  (see  page  561).  To  prepare  a 
silver  solution  which  is  intended  to  have  an  ounce  of  silver  to  the 
gallon  (see  p.  588),  observe  the  following  directions:  Dissolve  123 
ounces  of  cyanide  of  potassium  in  100  gallons  of  water ;  get  one 
or  two  flat  porous  vessels,  and  place  them  in  this  solution  to  within 
half  an  inch  of  the  mouth,  and  fill  them  to  the  same  height  with 
the  solution ;  in  these  porous  vessels  place  small  plates  or  sheets 
of  iron  or  copper,  and  connect  them  with  the  zinc  terminal  of  a 
battery  :  in  the  large  solution  place  a  sheet  or  sheets  of  silver  con- 
nected with  the  copper  terminal  of  the  battery.  This  arrangement 


690  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

being  made  at  night,  and  the  power  employed  being  two  of  Wol- 
laston's  batteries,  of  five  pairs  of  plates,  the  zincs  7  inches  square, 
it  will  be  found  in  the  morning  that  there  will  be  dissolved  from 
60  to  80  ounces  of  silver  from  the  sheets.  The  solution  is  now 
ready  for  use :  and  by  observing  that  the  articles  to  be  plated  have 
less  surface  than  the  silver  plate  forming  the  positive  electrode, 
for  the  first  two  days,  the  solution  will  then  have  the  proper 
quantity  of  silver  in  it.  We  have  occasionally  found  a  little  silver 
in  the  porous  cell :  it  is  therefore  not  advisable  to  throw  away  the 
solution  in  them  without  first  testing  it  for  silver,  which  is  done  by 
adding  a  little  muriatic  acid  to  it. 

The  amateur  electrotypist  may,  from  this  description,  make  up 
a  small  quantity  of  solution  for  silvering  his  medals  or  figures. 
For  example,  a  half-ounce  of  silver  to  the  gallon  of  solution  will 
do  very  well ;  a  small  quantity  may  be  prepared  in  little  more 
than  an  hour. 

As  the  cyanide  of  potassium  dissolves  silver  without  the  aid 
of  a  battery,  by  merely  allowing  a  piece  of  silver  to  steep  in 
this  solution  for  a  few  days,  a  plating  liquor  may  be  formed ; 
but  this  is  tedious  and  uncertain,  although  for  small  operations, 
and  where  porous  vessels  are  not  convenient,  it  will  serve  the 
purpose. 

Other  solutions  of  silver  may  be  employed  if  the  law  stated  at 
page  575  is  strictly  observed.  Indeed,  every  salt  of  silver  has  not 
only  been  tried,  but  is  either  the  subject  of  a  patent,  or  promi- 
nently included  in  it.  None  of  them,  however,  with  the  exception 
of  two,  have  we  found  of  any  practical  value,  besides  that  already 
described :  these  are  the  chloride  of  silver  dissolved  in  hyposul- 
phite of  soda,  and  the  sulphite  of  silver  dissolved  in  sulphite  of 
potash  or  sulphite  of  soda. 

HYPOSULPHITE  OF  SILVER  SOLUTION. — The  simplest  method 
known  to  us  for  forming  the  hyposulphite  of  silver  solution  is  this : 
Take  one  pound  of  pure  carbonate  of  soda,  well  dried,  as  de- 
scribed at  page  576  ;  mix  it  intimately  with  five  ounces  of  flour 
of  sulphur ;  place  the  mixture  over  a  slow  fire  without  flame  in  a 
porcelain  or  stoneware  basin,  which  must  be  supported  by  an  iron 
trelis,  or  any  convenient  support,  to  prevent  it  touching  the  red 
coal  or  flame ;  keep  the  mixture  constantly  stirring,  and  maintain 
the  heat  till  the  sulphur  melts,  and  the  mass  inclines  to  get  pasty 
and  rough.  While  in  this  state  keep  stirring  for  about  fifteen 
minutes,  in  order  to  bring  every  part  in  contact  with  the  air.  Set 
the  mixture  to  cool — after  which  dissolve  in  water.  Boil  the  so- 
lution for  some  time,  adding  sulphur ;  then  filter  it,  and  allow  it  to 
evaporate  at  a  slow  heat.  The  crystals  formed  are  hyposulphite 
of  soda. 

To  prepare  the  silver  solution,  the  silver  is  first  dissolved  in 
nitric  acid,  and  then  precipitated  by  a  solution  of  common  salt, 
and  washed,  with  the  precautions  stated  at  page  587.  When  the 
precipitated  chloride  of  silver  is  well  washed,  some  of  the  crystals 


ELECTKO-PLATING. 


591 


of  hyposulphite  of  soda  are  dissolved,  and  the  solution  is  added  to 
the  chloride  of  silver,  which  it  dissolves,  forming  the  plating  solu- 
tion. It  is  not  necessary  to  crystallize  the  hyposulphite  of  soda, 
if  used  as  soon  as  made. 

The  hyposulphite  of  silver  solution  is  very  easily  decomposed 
by  the  electric  current,  so  that  a  weak  battery  will  suffice  to  plate 
by  it:  but  its  great  objection  is  its  liability  to  decompose  in  the 
light,  and  to  deposit  the  silver  as  sulphuret :  unless  great  care  is 
exercised,  the  silver  deposited  from  it  will  be  in  a  granular  condi- 
tion, which  is  a  great  objection  in  plating. 

SULPHITE  'OF  SILVER  PLATING  SOLUTION. — The  sulphite  of 
silver  solution  is  prepared  in  the  following  manner,  as  described 
by  the  patentee  of  the  process : 

"The  solution  which  I  use  is  made  in  the  following  manner:  I 
take  of  the  best  pearl-ash  of  commerce  28  Ibs  (avoirdupois)  and 
add  to  it  30  Ibs  (avoirdupois)  of  water,  and  boil  them  in  an  iron 
vessel  until  the  pearl-ash  is  dissolved ;  the  solution  should  then  be 
poured  into  an  earthenware  or  other  suitable  vessel,  and  suffered 
to  stand  until  the  liquor  becomes  cold.  It  should  then  be  filtered, 
and  14  Ibs  (avoirdupois)  of  distilled  water  added  thereto ;  sulphurous 
acid  gas  (obtained  by  any  of  the  known  processes)  should  then  be 
passed  into  the  filtered  liquor  until  it  is  saturated,  taking  care  not 
to  add  sulphurous  acid  gas  in  excess.  The  liquor  should  be  again 
filtered,  and  the  liquor  so  filtered  is  what  I  term  the  solvent,  or 
sulphite  of  potash. 

"  To  make  the  silvering  liquor  which  I  use  in  coating  with  silver 
the  surface  of  articles  formed  of  metal  or 
metallic  alloys,  I  dissolve  12  oz.  (avoir- 
dupois) of  crystallized  nitrate  of  silver 
in  3  Ibs.  of  distilled  water  (in  a  clean 
earthenware  vessel),  and  add  to  the  solu- 
tion, by  a  little  at  a  time,  the  before- 
mentioned  solvent,  so  long  as  a  whitish 
colored  precipitate  is  produced  (care 
being  taken  not  to  add  more  of  the 
solvent  than  is  necessary).  After  the 
precipitate  has  subsided,  I  pour  off  the 
supernatant  liquor,  and  wash  the  pre- 
cipitate with  distilled  water.  To  the 
precipitate  I  add  as  much  of  the  before- 
mentioned  solvent  as  will  dissolve  it, 
and  afterwards  add  about  ^th  part  more 
of  the  solvent,  so  that  the  solvent  may 
be  in  excess;  I  then  stir  them  well  together  and  let  them  remain 
about  24  hours,  and  then  filter  the  solution,  when  it  will  be  ready 
for  use.  This  is  what  I  designate  silvering  liquor."* 

Sulphurous  acid  gas  for  making  the  above  liquor  may  be  pre- 


Fig.  581. 


*  Repertory  of  Patent  Inventions,  5th  series,  p.  210,  1843. 


592  THE   PRACTICAL   METAL-WOEKER'S  ASSISTANT. 

pared  by  heating  sulphuric  acid,  undiluted,  in  a  flask  or  any  con- 
venient  vessel,  to  which  should  be  added  small  pieces  of  copper  or 
charcoal:  the  gas  escaping  is  made  to  pass  into  the  solution  to  be 
saturated  with  it. 

Fig.  581  is  a  very  convenient  apparatus  for  the  preparation  of 
this  gas  for  saturating  solutions. 

This  solution  is  also  very  easily  decomposed  by  the  electric  cur- 
rent, and  serves  the  purposes  of  plating  very  well ;  but  it  is  also 
liable  to  decomposition  by  light,  and  is  not  so  good  in  practice  as 
the  solution  of  cyanide  of  potassium  and  silver.  The  latter  solu- 
tion is,  however,  liable  to  a  kind  of  decomposition  not  yet  fully 
investigated,  but  it  is  wholly  confined  to  its  impurities,  and  it  never 
deposits  its  silver;  whereas  the  decomposition  that  takes  place  in. 
the  sulphite  or  hyposulphite  affects  the  silver  compound,  and  pre- 
cipitates the  silver  from  solution. 

To  EECOVER  SILVER  FROM  SOLUTION. — When  a  silver  solution 
gets  out  of  order,  and  cannot  be  rendered  fit  for  use  again,  the 
silver  may  be  recovered  by  adding  to  the  solution  any  acid  that 
will  neutralize  the  alkali ;  if  nitric  or  sulphuric  acid  be  used,  the 
silver  precipitates  as  cyanide,  but  if  hydrochloric  acid  be  used,  the 
silver  will  be  precipitated  as  a  chloride :  in  either  case  .the  solution 
should  be  diluted,  or  a  portion  of  the  precipitate  will  be  re-dissolved. 
The  precipitate  is  allowed  to  deposit,  the  clear  liquor  decanted,  and 
the  vessel  filled  with  water  to  wash  the  precipitate,  which  is  after- 
wards collected  upon  a  filter  and  dried,  and  then  mixed  with  twice 
its  weight  of  carbonate  of  potash,  and  fused  in  a  Hessian  crucible 
for  15  minutes,  or  until  the  fused  fluid  ceases  to  effervesce.  On 
removing  the  crucible,  and  pouring  the  whole  into  an  iron  ladle, 
when  cool  the  silver  will  be  found  in  the  metallic  state  at  the  bot- 
tom of  the  ladle. 

In  these  operations  when  pouring  the  acid  into  the  cyanide 
solution,  great  care  must  be  taken  not  to  inhale  the  fumes  given 
off,  which  are  very  abundant,  sickening,  and  poisonous.  The 
operation  should  be  done  in  the  open  air,  and  even  then  it  is  bad. 
Instead  of  throwing  down  the  silver  by  an  acid  it  is  better  to  evap- 
orate the  solution  to  dry  ness,  and  to  fuse  the  product  as  described; 
in  which  case  the  cyanide  is  an  excellent  reducing  flux,  requiring 
no  addition  of  carbonate  of  potash,  and  saves  the  necessity  of  evolv- 
ing poisonous  fumes. 

When  the  solution  has  contained  yellow  prussiate  of  potash,  it 
is  found  that  during  this  fusion  portions  of  the  metal  sometimes 
form  a  scoriaceous  nodule  at  the  bottom  of  the  crucible,  and  all  the 
heat  that  can  be  applied  by  an  ordinary  assay  furnace  will  not  fuse 
it.  This  refractory  piece,  when  cooled,  has  generally  a  rough 
scoriaceous  surface,  and  is  exceedingly  hard.  When  filed  it  has  more 
the  color  of  German  silver  than  of  real  silver;  it  has  considerable 
malleability,  and  retains  its  bright  appearance  for  a  long  time  witl- 
out  tarnish.  An  analysis  of  this  alloy  gave — 


ELECTRO-PLATING.  593 

Silver    .    .     .  'V'^-:;    .  82-15 

Copper 9-12 

Iron 7'50 

Carbonaceous  matter   .     .  '46 

99-23 

If  we  suppose  the  carbonaceous  matter  to  be  an  accidental  im- 
purity, this  alloy  will  nearly  agree  with  the  formula  Ag3  Cu  Fe. 

PREPARATION  OF  ARTICLES  FOR  PLATING. — Articles  that  are  to 
be  plated  are  first  boiled  in  an  alkaline  ley,  to  free  them  from 
grease,  then  washed  from  the  ley,  and  dipped  into  dilute  nitric 
acid,  which  removes  any  oxide  that  may  be  formed  upon  the  sur- 
face ;  they  are  afterwards  brushed  over  with  a  hard  brush  and  sand, 
of  which  a  kind  obtained  from  the  Isle  of  Wight,  and  known  as 
silver-sand  is  best.  The  alkaline  ley  should  be  in  a  caustic  state, 
which  is  easily  effected  by  boiling  the  carbonated  alkali  with  slaked 
lime,  until,  on  the  addition  of  a  little  acid  to  a  small  drop  of  the  solu- 
tion, no  effervescence  occurs.  The  lime  is  then  allowed  to  settle,  and 
the  clear  liquor  is  fit  for  use.  The  ley  should  have  about  half-a- 
pound  of  soda-ash,  or  pearl  ash,  to  the  gallon  of  water.  The  nitric 
acid,  into  which  the  article  is  dipped,  may  be  diluted  to  such  au 
extent  that  it  will  merely  act  upon  the  metal.  Any  old  acid  will 
do  for  this  purpose.  In  large  factories  the  acid  used  for  dipping 
before  plating  is  generally  afterwards  employed  for  the  above  pur- 
pose of  cleaning. 

The  article  being  thoroughly  cleaned  and  dried,  has  a  copper 
wire  attached  to  it,  either  by  twisting  it  round  the  article  or  putting 
it  through  any  open  part  of  it,  to  maintain  it  in  suspension.  It  is 
then  dipped  into  nitric  acid  as  quickly  as  possible,  and  washed 
through  water,  and  then  immersed  in  the  silver  solution,  suspend- 
ing it  by  the  wire  which  crosses  the  mouth  of  the  vessel  from  the  zinc 
of  the  battery.  'The  nitric  acid  generally  used  and  found  best  for 
dipping  has  a  specific  gravity  1*518,  contains  10  per  cent,  sulphuric 
acid,  and  is  got  at  about  6  cts.  per  Ib.  The  article  is  instantaneously 
coated  with  silver,  and  ought  to  be  taken  out  after  a  few  seconds 
and  well  brushed.  On  a  large  scale,  brushes  of  brass  wire  attached 
to  a  lath  are  used  for  this  purpose;  but  a  hard  hair  brush  with  u 
little  fine  sand  will  do  for  small  work.  This  brushing  is  used  in 
case  any  particle  of  foreign  matter  may  be  still  on  the  surface.  It 
is  then  replaced  in  the  solution,  and  in  the  course  of  a  few  hours,  u 
coating  of  the  thickness  of  tissue-paper  is  deposited  on  it,  having 
the  beautiful  matted  appearance  of  dead  silver.  If  it  is  desired  to 
preserve  the  surface  in  this  condition,  the  article  must  be  taken 
out,  care  being  taken  not  to  touch  it  by  the  hand,  and  immersed  in 
boiling  distilled  water  for  a  few  minutes.  On  being  withdrawn, 
sufficient  heat  has  been  imparted  to  the  metal  to  dry  it  instantly.  If 
it  is  a  medal,  it  ought  to  be  put  in  an  air-tight  frame  immediately, 
or  if  a  figure,  it  may  be  at  once  placed  under  a  glass  shade,  as  a 
38 


594  THE   PRACTICAL   METAL-WORKERS  ASSISTANT. 

very  few  days  exposure  to  the  air  tarnishes  it,  by  the  formation  of 
sulphuret  of  silver,  and  that  more  especially  in  a  room  where  there 
is  fire  or  gas.  If  the  article  is  not  wanted  to  have  a  dead  surface, 
it  is  brushed  with  a  wire  brush,  and  old  ale,  beer,  or  water  contain- 
ing  in  solution  a  little  gum,  glue,  or  sugar,  but  the  amateur  may  use 
a  hard  hair  brush.  It  may  be  afterwards  burnished  according  to 
the  usual  method  of  burnishing,  by  rubbing  the  surface  with  con- 
siderable pressure  with  polished  steel  or  the  mineral  termed  blood- 
stone. .  y 

We  may  remark,  that  in  depositing  silver  from  the  solution,  a 
weak  battery  may  be  used ;  though  when  the  battery  is  weak  the 
silver  deposited  is  soft,  but  if  used  as  strong  as  the  solution  will 
allow,  say  8  or  9  pairs,  the  silver  will  be  equal  in  hardness  to  rolled 
or  hammered  silver.  If  the  battery  is  stronger  than  the  solution 
will  stand,  or  the  article  very  small  compared  to  the  size  of  the 
plate  of  silver  forming  the  positive  electrode,  the  silver  will  be  de- 
posited as  a  powder.  The  average  cost  of  depositing  silver  in  this 
way  is  4  cts.  per  ounce.  Gas  should  never  be  seen  escaping  from 
either  pole :  and  the  surface  of  the  article  should  always  correspond 
as  nearly  as  possible  with  that  of  the  positive  electrode,  otherwise 
the  deposit  runs  the  risk  of  not  being  good ;  it  requires  more  care, 
and  the  solution  is  apt  to  be  altered  in  strength,  because  if  the 
positive  electrode  be  large  compared  with  the  negative,  the  solu- 
tion will  become  stronger  in  silver,  while  if  smaller  in  proportion 
the  solution  will  become  exhausted  of  silver. 

In  plating  large  articles  (such  as  those  plated  in  factories),  it  is 
not  always  sufficient  to  dip  them  in  nitric  acid;  wash  and  immerse 
them  in  the  solution,  in  order  to  effect  a  perfect  adhesion  of  the 
two  metals.  To  secure  this,  a  small  portion  of  quicksilver  is  dis- 
solved in  nitric  acid,  and  a  little  of  this  solution  is  added  to  water, 
in  sufficient  quantity  to  enable  it  to  give  a  white  silvery  tint  to  a 
piece  of  copper  when  dipped  into  it:  the  article  then,  whether  made 
of  copper,  brass,  or  German  silver,  is,  after  being  dipped  in  the 
nitric  acid  and  washed,  dipped  into  the  nitrate  of  mercury  solution 
till  the  surface  is  white :  it  is  then  well  washed  by  plunging  it  into 
two  separate  vessels  containing  clean  water,  and  finally  put  into 
the  plating  solution.  This  secures  perfect  adhesion  of  the  metals. 
One  ounce  of  quicksilver  thus  dissolved  will  do  for  a  long  time, 
though  the  liquor  is  used  every  day.  When  the  mercury  in  this 
solution  is  exhausted,  it  is  liable  to  turn  the  article  black  upon 
being  dipped  into  it:  this  must  be  avoided,  as  in  that  case  it  also 
causes  the  deposited  metal  to  strip  off. 

PRACTICAL  INSTRUCTIONS  IN  PLATING.— We  need  hardly  add 
that  it  is  necessary  that  the  battery  should  be  so  arranged,  that  the 
quantity  of  electricity  generated  should  correspond  with  the  sur- 
face of  the  articles  to  be  coated,  and  that  the  intensity  should  bear 
reference  to  the  state  of  the  solutions;  that  is  to  say,  that  the 
quantity  should  be  sufficient  to  give  the  required  coating  of  metal 
in  a  given  time,  and  the  intensity  such  as  to  cause  the  electricity  to 


ELECTRO-PLATING. 


595 


pass  through  the  solution  to  the  articles.  It  is  also  essential  for 
regular  working,  as  stated  above,  that  the  plates  of  metal  forming 
the  positive  pole  in  the  solution  should  be  of  corresponding  sur- 
face to  the  articles  to  be  coated,  and  face  them  on  both  sides. 

The  following  is  the  arrangement  adopted  in  some  of  the  large 
plating  manufactories: — The  vat,  or  plating  vessel  measures  about 
6 1  feet  in  length,  by  33  inches  in  breadth,  and  33  inches  in  depth, 
and  generally  contains  from  200  to  250  gallons  of  solution ;  the 
silver  plates  serving  as  electrodes,  whiclj.  were  formerly  nailed 
upon  frames  of  wood,  are  now  generally  fixed  upon  light  iron 
frames,  these  not  being  affected  by  the  solution:  two  battery 
troughs  are  arranged  as  seen  in  Fig.  582,  consisting  of  6  batteries 
of  three  pairs  intensity.  The  zinc  plates  immersed  in  the  acid 
measure  6  inches  by  7  inches,  the  exposed  surfaces  of  which 
measure  84  square  inches :  these  multiplied  by  6  give  504  square 
inches,  from  which  electricity  is  disengaged.  The  surface  of  the 
silver  electrodes  exposed  to  the  articles  receiving  the  deposit  vary 
from  3000  to  4000  square  inches  of  surface. 

The  following  figure,  with  explanation,  will  illustrate  these  ob- 
servations : 

Fig.  582. 


\ 


A,  Vat  or  vessel  containing  the  solution;  B,  Battery  with  zinc  pole 
z,  connected  with  rods  R  R ;  and  copper  pole  c,  connected  with  the 
metallic  sheets  P  P,  in  the  solution,  by  means  of  the  copper  slip  F ; 
D  D,  are  articles  suspended  in  the  solution  by  wires  from  the  rods 
R  R;  s,  the  solution.  So  soon  as  the  articles,  which  are  connected 
with  the  negative  pole  of  the  battery,  and  the  metallic  sheets,  con- 


596  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

nected  with  the  positive  pole,  are  both  immersed  in  the  solution, 
the  galvanic  circuit  is  completed. 

In  most  plating  establishments  the  batteries  are  now  placed  out- 
side the  house,  and  the  connecting  rods  are  brought  from  them  into 
the  vats,  so  as  to  preserve  the  workmen  from  the  injury  arising 
from  inhaling  the  hydrogen  gas  which  is  given  off  by  the  zincs,  as 
it  often  contains  arsenic,  and  hence  is  highly  injurious  to  health ; 
the  gas  of  the  battery  has  a  strong  effect  upon  the  nostril,  exciting 
dryness  with  pain.  Wherever  the  batteries  are  placed,  they  should 
not  be  exposed  to  cold,  as  their  operation  is  much  affected  by  the 
temperature. 

In  the  early  days  of  electro-plating  the  batteries  used  were  round. 
They  consisted  of  a  copper  cylindrical  vessel,  about  20  inches  deep, 
and  5  inches  diameter,  filled  with  dilute  sulphuric  acid.  A  piece  of 
wood  was  placed  at  the  bottom  of  this  vessel,  and  a  cylinder  of  zinc, 
the  same  depth  as  the  copper  vessel,  and  about  3  inches  diameter, 
was  placed  inside  the  copper  vessel.  A  wooden  ring,  floating  on 
the  surface  of  the  acid,  prevented  the  zinc  and  copper  touching — a 
binding  screw  was  attached  to  each,  and  formed  a  battery  of  a  single 
pair.  Six  batteries  of  this  size  were  connected  with  such  a  vat  as  is 
described  above.  The  test  of  strength  employed  to  determine 
whether  the  working  power  was  sufficient,  was  that,  when  connected 
with  an  electro-magnet,  it  should  support  a  7  Ib.  weight.  We  be- 
lieve that  many  platers  and  gilders  still  use  such  batteries,  and  that, 
when  the  solutions  and  apparatus  are  all  in  good  condition,  they  do 
well.  They  are,  however,  far  from  being  so  economical  as  the  bat- 
tery with  square  plates  shown  above.  Some  electro-metallurgists 
use  large  and  deep  stoneware  vessels  in  which  are  placed  the  zinc 
and  copper — the  plates  having  several  square  feet  of  surface.  We 
have  already  shown,  .when  treating  of  batteries,  that  very  large 
plates  are  not  consistent  with  economy. 

To  ascertain  the  amount  of  metal  deposited,  it  is  only  necessary 
to  weigh  the  articles  carefully  before  and  after  plating.  But  be- 
tween the  first  weighing  and  the  immersion  of  the  articles  in  the 
plating  solution  there  is  the  dipping  into  nitric  acid  to  be  ac- 
counted for:  this,  on  an  average,  will  cause  a  loss  of  about  one 
pennyweight  upon  an  article  of  the  size  of  a  foot  square;  thus,  if  a 
waiter  of  a  foot  square,  made  of  copper  or  German  silver,  shows, 
when  coated,  a  difference  in  weight  of  19  pennyweights,  the  silver 
laid  on  must  be  estimated  at  an  ounce,  or  20  pennyweights.  When 
the  article  is  a  "  replate,"  i.  e.,  an  old  plated  article  that  has  become 
bare  of  silver  in  parts,  the  allowance  or  reduction  for  the  dipping  in 
the  acid  is  only  to  include  the  portions  left  bare,  for  the  silvered 
parts  are  not  acted  upon  by  it.  One  of  the  practical  difficulties 
which  the  inexperienced  will  occasionally  meet  with  when  a  "  re- 
plate"  is  dipped  in  the  nitric  acid,  is,  that  a  galvanic  action  is  pro- 
duced between  the  silver  and  the  copper  portions,  which  causes  a 
black  line  round  the  edge  of  the  silver:  this  ought  immediately  to 
be  rubbed  off)  but  even  with  rapid  and  careful  rubbing  there  is 


ELECTRO-PLATING.  597 

great  danger  that  the  coating  will  loosen  and  blister  at  those  parts ; 
and  beside  this,  it  happens  that  the  parts  of  the  "  replate"  which 
are  sound,  the  silver  not  being  acted  upon  by  the  acid,  but  rather 
protected  by  the  galvanic  action,  are  not  in  a  fit  state  to  receive  and 
maintain  a  perfect  adhesion  of  the  deposit,  and  therefore  the  risk  is 
great  that  the  new  coating  will  separate  from  the  old,  or,  in  technical 
language,  that  the  part  will  strip.  Under  these  circumstances 
experience  has  taught  that  the  best  way  to  proceed  is  to  take  all 
the  old  silver  off  the  article,  and  deposit  an  entirely  new  coating. 

There  are  two  methods  of  taking  off  the  silver : 

TAKING  SILVER  FROM  COPPER,  ETC. — First,  stripping  or  dissolving 
it  off;  this  is  done  bytputting  into  a  stoneware  or  copper  pan  some 
strong  sulphuric  acid  (vitriol),  to  which  a  little  nitrate  of  potash  is 
added :  the  article  is  laid  into  this  solution,  which  will  dissolve  the 
silver  without  materially  affecting  the  copper ;  saltpetre  is  added 
by  degrees,  as  occasion  requires ;  and  if  the  action  is  sl6w  a  little 
heat  is  applied  to  the  vessel.  The  silver  being  removed,  the  article 
is  washed  well  and  then  passed  through  the  potash  solution,  and 
finished  for  plating.  When  the  sulphuric  acid  becomes  saturated 
with  silver  it  is  diluted,  and  the  silver  is  precipitated  by  a  solution 
of  common  salt:  the  chloride  of  silver  formed  is  collected  and  fused 
in  a  crucible  with  carbonate  of  potash,  when  the  silver  is  obtained 
in  a  metallic  state,  as  a  knob  or  button.  The  'crucible  should  not 
be  over  two-thirds  full  and  should  be  kept  in  fusion  till  effervescence 
ceases.  The  crucible  is  then  removed  from  the  fire,  and,  when  cool, 
it  is  broken. 

The  article  thus  stripped  by  acids  often  shows  a  little  roughness, 
not  from  the  effects  of  the  acid,  but  because  the  copper  under  the 
silver  has  not  been  polished ;  it  is  therefore  a  necessary  practice  in 
the  electro-plating  factories  to  polish  the  articles  before  plating. 
This  is  done  by  means  of  a  circular  brush,  more  or  less  hard  as  re- 
quired, fixed  upon  a  lath,  and  a  thin  paste  made  of  oil  and  pumice- 
stone  ground  as  fine  as  flour.  By  this  process  the  surface  of  any 
article  can  be  smoothened  and  polished ;  but  a  little  experience  is 
required  to  ensure  success,  and  enable  the  operator  to  polish  the 
surface  equally  without  leaving  brush  marks.  We  need  scarcely 
say,  that  after  this  process  the  article  must  be  cleaned  in  potash 
before  it  is  plated. 

Second  Method. — Instead  of  stripping  off  the  silver  by  means  of 
acid,  it  is  a  more  common  and  preferable  mode  to  brush  off  the 
silver  by  the  operation  just  described.  In  this  case  the  brushings 
must  be  collected,  dried,  and  burned ;  this  may  be  done  in  an  iron 
pan,  keeping  it  at  a  red  heat  until  all  carbonaceous  matters  are 
consumed,  the  remainder  is  fused  with  carbonate  of  soda  or  potash, 
when  the  silver  is  obtained,  in  combination  with  a  little  copper. 

CYANIDE  OF  SILVER  AND  POTASSIUM,  ITS  DECOMPOSITION  DUR- 
ING THE  PLATING  PROCESS. — The  silver  salt  in  the  plating  solution 
is  a  true  double  salt,  being,  as  already  described,  a  compound  of 
one  equivalent  of  cyanide  of  silver,  and  one  of  cyanide  of  potassium 


598 


THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 


Fig.  583. 


— two  distinct  salts.  In  the  decomposition  of  the  silver  solution 
by  the  electric  current,  the  former,  cyanide  of  silver,  is  alone 
affected :  the  silver  is  deposited,  and  the  cyanogen  passes  to  the 
positive  plate  or  electrode.  The  cyanide  of  potassium  is  therefore 
set  at  liberty  upon  the  surface  of  the  article  receiving  the  silver 
deposition,  and  its  solution  being  specifically  lighter  than  the  gen- 
eral mass  of  the  plating  solution,  rises  to  the  top :  this  causes  a 
current  to  take  place  along  the  face  of  the  article  being  plated.  If 
the  article  has  a  flat  surface,  suppose  that  of  a  waiter  or  tray,  upon 
which  a  prominence  exists,  as  a  mounting  round  the  edge,  such  as 
a  gadroon,  see  Fig.  583,  it  will  cause  lines  and  ridges  from  the  bot- 
tom to  the  top,  as  already  described  at  page 
561.  Newly-formed  solutions  are  most  sub- 
ject to  produce  this  annoyance. 

OTHER  EFFECTS  PRODUCED  IN  WORKING. 
— As  the  cyanogen  combines  with  the  silver 
plate  forming  the  positive  electrode,  it  is  dis- 
solved by  the  free  cyanide  of  potassium, 
which  the  solution  must  have;  and,  being 
specifically  heavier,  sinks  to  the  bottom,  by 
which  a  current  downwards  is  excited:  this 
is  of  no  greater  annoyance  than  that  it  ren- 
ders the  solution  of  unequal  density,  which 
in  its  turn  yields  an  unequal  deposit,  more 
being  laid  upon  the  lower  parts  of  the 
article  than  on  the  upper:  the  silver  plate 
also  is  destroyed  more  rapidly  at  the  bottom 
than  at  the  top,  except  at  the  surface  of  the 
solution,  if  the  silver  be  above  it,  where  the 
plate  gets  cut  through.  In  a  new  solution, 

which  contained  1|  ounces  of  silver  to  the  gallon,  we  have  found, 
just  before  taking  out  the  articles,  that  the  top  part  of  the  solution  con- 
tained 200  grains  of  silver  less,  and  the  bottom  part  200  grains  more 
per  gallon,  than  when  the  articles  were  put  into  it.  These  difficulties 
and  annoyances  may,  however,  be  nearly  surmounted  by  keeping  the 
articles  in  motion:  agitating  or  stirring  the  solution  occasionally 
would  also  obviate  these  annoyances ;  but  this  is  not  advisable,  for 
if  the  sediment  (which  always  forms)  were  stirred  up  it  Would  settle 
upon  the  face  of  the  articles  and  make  them  rough.  Where  there  is 
engine  power  it  is  an  easy  matter  to  keep  the  articles  in  motion ; 
but  where  this  power  is  not  available,  a  very  simple  apparatus,  in- 
vented by  Mr.  Alexander  Mitchell,  of  Glasgow,  may  be  fitted  up  at 
a  trifling  cost,  to  give  the  necessary  motion  by  clockwork.  The 
annexed  sketch  exhibits  this  apparatus. 

MACHINE  FOR  MOVING  GOODS  WHILE  SUBJECTING  TO  THE  ELEC- 
TRO-PLATING PROCESS.— Fig.  584,  side  elevation,  with  front  frame 
off^  Fig.  585,  end  elevation  of  that  part  of  front  frame  where  the 
fly  is  held ;  Figs.  586  and  587,  the  plating  vat,  with  frame  moving 
on  inclined  plane. 


ELECTRO-PLATING. 


599 


The  large  wheel  A,  Fig.  585,  is  propelled  by  a  weight  suspended 
from  the  roof  by  a  card  which  winds  round  its  barrel,  the  same  as 
common  clockwork.  The  circumference  is  studded  with  small  pins 
which  catch  the  arm  B,  moving  it  in  a  downward  direction,  and 
consequently  moving  the  arm  c  in  a  forward  direction.  The  latter, 
being  attached  to  the  frame  by  a  small  rod  B,  Figs.  585  and  587, 
moves  it  up  the  inclined  plane  E,  Fig.  587,  until  the  pin  fixed  in 
the  wheel  A  passes  the  end  of  the  arm  B.  The  frame  then  moving 
down  the  incline  E,  brings  B  in  gear  with  the  next  pin,  and  the 
same  motion  again  takes  place,  and  so  on  successively.  The  speed 


Figs.  584 


'585. 


is  regulated  by  the  train  moving  in  an  endless  screw  fitted  on  the 
last  wheel  of  the  arbor  of  a  fan.  The  four  hflles  in  Fig.  585,  are 
for  bolts  or  pillows  for  screwing  the  two  frames  together.  The 
frame  has  four  pulleys  and  inclines,  the  latter  adjustable  to  a 
greater  or  less  degree  by  the  screw  and  grove  at  E. 

DEPOSIT  DISSOLVING  OFF  IN  SOLUTION.— In  depositing  any 
metal,  but  more  particularly  such  as  require  solutions  having  an 
excess  of  the  solvent,  su<3h  as  of  cyanide  of  potassium  in  the  de- 
positing of  gold  and  silver,  care  should  be  taken  that  nothing  stops 


600 


THE   PKACTICAL   METAL-WORKER'S   ASSISTANT. 


the  current  of  electricity  suddenly,  while  the  article  being  deposited 
upon  remains  in  the  solution,  otherwise  the  metal  deposited  will 
speedily  dissolve  off.  This  we  have  often  experienced,  and  many 
others  have  no  doubt  done  the  same.  Indeed,  we  have  seen  a 
beautiful  deposit  going  on,  and  left  the  operation  with  great  hope 
of  excellent  results,  but  on  returning  shortly  after  have  found  the 
whole  dissolved  off.  And  often,  when  the_  process  was  apparently 
goino-  on  well,  and  the  articles  had  been  in  the  solution  the  usual 
time&to  receive  a  fair  coating  of  metal,  upon  taking  them  out  and 
weighing  them  there  was  hardly  any  perceptible  difference  from 
the  original  weight — in  short,  there  had  been  no  material  deposit. 
These  phenomena  will  be  found  to  occur  with  the  greatest  fre- 
quency when  the  solutions  and  the  batteries  are  in  the  best  con- 
dition for  working,  and  when  the  article  upon  which  the  deposit 
is  going  on,  and  the  pole  or  plate  of  metal  forming  the  positive 


PL 

,k 


Fig.  586, 


Fig.  587. 


electrode  are  at  a  considerable  distance  from  each  other.  But  be- 
fore explaining  what  we  consider  to  be  the  cause  of  these  an- 
noyances we  will  refer  to  another  phenomenon  connected  with 
them. 

OPPOSITE  CURRENTS  OF  ELECTRICITY  FROM  VATS. — If,  under 
the  circumstances  inferred  to,  and  when  the  deposit  has  gone  on  for 
some  time,  the  wires  connecting  the  battery  with  the  electrodes  in 
the  depositing  solution  be  disconnected  from  the  battery,  and  their 
two  ends  be  joined  together,  a  current  of  electricity  nearly  as 
strong  as  that  from  the  battery  will  pass  through  the  wires,  but 
in  the  opposite  direction  from  that  which  was  obtained  by  the  bat- 
tery ;  and  if  two  pieces  of  metal  were  attached  to  these  wires  and 
put  into  a  solution  of  copper,  or  any  metal,  a  deposition  would 


ELECTRO-PLATING.  601 

occur,  the  original  electrodes  now  constituting  a  battery  in  relation 
to  this  second  decomposition  cell :  the  current,  however,  would 
gradually  weaken  until  it  ceased.  The  cause  of  all  these  actions 
and  reactions  is  this  :  The  article  being  plated  with  silver  in  con- 
nection with  the  battery,  exhausts  the  solution  of  silver  around  it, 
leaving  free  cyanide  of  potassium  in  solution,  while  around  the 
sheet  of  silver  which  is  serving  as  the  positive  electrode,  the  solu- 
tion is  on  the  contrary  becoming  saturated  with  silver,  so  that  we 
have  all  the  conditions  necessary  to  constitute  a  battery,  having 
silver  in  two  kinds  of  solution — the  one  capable  of  dissolving 
silver,  the  other  not.  In  these  conditions  lies  the  source  of  the 
annoyances  described  above.  From  the  moment  the  deposition  of 
metal  begins,  there  also  arises  an  opposite  current  of  electricity, 
tending  to  neutralize  the  effects  of  the  battery,  which  current  goes 
on  increasing  in  quantity  until  the  two  currents  neutralize  each 
other,  or  it  may  be  until  the  current  from  the  trough  overpowers 
that  from  the  battery.  In  the  latter  case,  as  we  have  said,  there 
may,  at  the  termination  of -the  ordinary  period,  be  little  or  no 
silver  deposited  on  the  articles  intended  to  be  plated.  Motion  in 
the  silver  or  depositing  solution  will  prevent  all  these  annoy- 
ances ;  and  this  being  now  generally  adopted,  these  phenomena  are 
not  now  observed,  but  the  effects  take  place  less  or  more  in  every 

solution. 
TEST  FOR  THE  QUANTITY  OF  FREE  CYANIDE  OF  POTASSIUM  IN 

SOLUTIONS. — It  has  been  already  mentioned  that  the  cyanide  of 

silver,  as  it  forms  upon  the  surface  of  the  silver  plate,  is  dissolved 

by  the  cyanide  of  potassium.     'This  renders  it  necessary  to  have 

always  in  the  solution  free  cyanide  of  potassium.     Were  we  to 

use  the  pure  crystalline  salt  of  cyanide  of  potassium  and  silver, 

dissolved  in  water,  without  any  free  cyanide  of 

potassium,  we  should  not  obtain  a  deposit  be-  Fie-  588. 

yond  a  momentary  blush;  as  the  silver  plate  or 

electrode  would  get  an  instantaneous  coating  of 

cyanide  of  silver,  and  this  not  being  dissolved 

the  current  would  stop.     The  quantity  of  free 

cyanide  of  potassium  required  in  the  solution 

varies  according  to  the  amount  of  silver  that  is. 

present,  and  the  rapidity  of  the  deposition.     If 

there  be  too  little  of  it,  the  deposk  will  go  on 

slowly ;  if  there  be  too  much,  the  silver  plate 

will  be  dissolved  in  greater  proportion  than  the 

quantity  deposited,  and  the  solution  will  conse- 
quently get  stronger.     The  proportion  we  have 

found  best  is  about  half  by  weight  of  free  cyanide 

of  potassium  to  the  quantity  of  silver  in  solution ; 

thus,  if  the  solution  contains  two  ounces  of  silver 

to  the  gallon,  it  should  have  one  ounce  of  free 

cyanide  of  potassium  per  gallon.    This  is  known 

by  taking  some  nitrate  of  silver,  dissolving  it  in  distilled  water, 


602  THE   PRACTICAL  METAL-WORKER'S  ASSISTANT. 

and  placing  it  in  a  common  alkalimeter*,  graduated  into  100  parts, 
Fig.  588.  The  proportion  of  the  nitrate  of  silver  in  the  solution  is 
that  every  two  graduations  of  the  solution  should  contain  1  grain. 
A  given  quantity  of  the  plating  solution  is  now  taken — say  1  ounce 
by  measure,  and  the  test  solution  of  nitrate  of  silver  is  added  to  it 
by  degrees,  so  long  as  the  precipitate  formed  is  redissolved.  When 
this  ceases  the  number  of  graduations  is  then  noted,  and  the  follow- 
ing equation  gives  the  quantity  of  free  cyanide.  Every  175  nitrate 
of  silver  are  equal  to  130  cyanide  of  potassium  in  solution.  Sup- 
pose 20  graduations  were  taken,  equal  to  10  grains  nitrate  of  silver, 
then  175:  130  :  :  10  :  7.4  grains  free  cyanide  of  potassium.  This, 
multiplied  by  160,  the  number  of  fluid  ounces  per  gallon,  will  make 
about  2 1  ounces.  We  have  taken  2  graduations  to  one  grain  of 
nitrate  of  silver,  that  the  solution  may  be  considerably  dilute  and 
less  liable  to  error.  The  following  table  is  calculated  at  a  half 
grain  nitrate  of  silver  to  the  graduation,  and  will  be  a  guide  to  the 
student  or  workman.  The  quantity  of  solution  tested  is  one  ounce 
by  measure.  's  ,*' 


Number  of 
graduations  used. 

Free  cyanide  per  gallon, 
oz.      dwt.       gr. 

1      .      .      .     . 

0 

2 

13 

2     .     .     .     . 

0 

5 

3 

3     .     .     .    . 

0 

7 

16 

4    .    .     .    . 

.......    0 

10 

6 

5     .     .     .     . 

0 

12 

19 

6     .     .    .    . 

0 

'  15 

9 

7    .    .    .    . 

0 

17 

22 

8    .    .     .     . 

1 

0 

13 

9     .     .     .     . 

1 

3 

1 

10     .    .    .    . 

1 

5 

12 

11     .    .     .    . 

1 

8 

5 

,12     .     .     .     . 

......   1 

10 

19 

13     .     .     .     . 

1 

13 

8 

14    .     .     .     . 

1 

15 

22 

15     .     .     .     , 

1 

18 

11 

16     .     .     , 

2 

1 

2 

17    .    .  '    , 

2 

3 

14 

18    .    .    .    , 

2 

6 

2 

19    ... 

2 

8 

11 

20     .    .    .    . 

......    2 

11 

0 

Another  method  may  be  adopted.  If,  for  instance,  we  dissolve 
a  small  quantity  of  sulphate  of  copper  and  add  to  it  an  excess  of 
ammonia,  there  is  produced  a  deep  blue  color.  Cyanide  of  po- 
tassium will  destroy  the  blue  color,  in  a  fixed  chemical  proportion. 
To  obtain  this  proportion,  take  ten  grains  of  pure  cyanide  of  po- 
tassium and  dissplve  in  water ;  then  take  a  certain  quantity,  say 
100  grams,  of  sulphate  of  copper  and  convert  it  into  ammoniuret, 
the  whole  measuring  a  given  quantity,  and  pour  from  an  alkalime- 


ELECTRO-PLATING.  603 

ter  this  blue  liquor  into  the  cyanide  of  potassium  till  it  ceases  to 
destroy  the  color,  then  mark  the  number  of  graduations  required, 
and  that  amount  of  copper  solution  will  represent  10  grains  cyanide 
of  potassium — a  quantitative  test  will  thus  be  got  for  the  full  cyan- 
ide of  potassium  in  the  solution,  and  should  be  used  as  follows : 
Say  that  the  color  of  60  graduations  of  the  blue  solution  was  de- 
stroyed by  the  10  grains  of  cyanide  of  potassium,  then  to  test  the 
quantity  of  free  cyanide  of  potassium  in  the  plating  solution,  take 
60  graduations  of  the  blue  liquor  in  any  convenient  vessel,  and 
add  to  it  from  an  alkalimeter  the  plating  solution  till  the  color  of 
the  blue  liquor  is  destroyed,  then  note  the  quantity  which  contains 
10  grains  free  cyanide,  from  which  the  quantity  in  the  whole 
solution  may  be  calculated. 

RATE  OF  DEPOSITING  SILVER. — When  articles  are  taken  out  of 
the  solution  they  are  swilled  in  water,  and  then  put  into  boiling 
water.  They  are  afterwards  put  into  hot  sawdust,  which  dries 
them  perfectly.  Their  color  is  chalk-white.  They  are  generally 
weighed  before  being  scratch-brushed ;  that  is,  brushed  with  the 
fine  wire  brushes  and  stale  beer  as  already  described.  Although 
this  operation  does  not  displace  any  of  the  silver,  still,  in  taking 
off  the  chalky  appearance,  there  is  a  slight  loss  of  weight.  The 
appearance  after  scratching  is  that  of  bright  metallic  silver.  Any 
thickness  of  silver  may  be  given  to  a  plate  by  continuing  the 
operation  a  proper  length  of  time.  One  ounce  and  a  quarter  to  one 
ounce  and  a  half  of  silver  to  the  square  foot  of  surface,  will  give 
an  excellent  plate  about  the  thickness  of  ordinary  writing  paper. 

BRIGHT  DEPOSIT. — A  little  sulphuret  of  carbon  added  to  the 
plating  solution  prevents  the  chalky  appearance,  and  gives  the 
deposit  the  appearance  of  metallic  silver;  the  reaction  which  takes 
place  in  this  mixture  is  not  yet  understood.  The  best  method  of 
applying  the  sulphuret  of  carbon  is  to  put  one  or  two  ounces  into 
a  large  bottle,  then  fill  it  with  strong  silver  solution,  having  an 
excess  of  cyanide  of  potassium,  and  let  it  repose  for  several  days, 
shaking  it  occasionally.  A  little  of  this  silver  solution  is  added, 
as  required,  to  this  plating  solution,  which  will  give  the  articles 
plated  the  same  appearance  as  if  scratched.  It  is  also  found  that 
the  presence  of  sulphuret  of  carbon  prevents  the  solution  from 
going  out  of  order ;  indeed  we  have  seen  a  solution  that  has  been 
constantly  working  from  two  to  three  years,  while,  generally,  they 
were  subject  to  go  out  of  order  for  a  time,  in  less  than  one  year — 
although,  after  standing  a  time,  they  would  recover — but  these  arc 
curious  reactions  not  yet  investigated. 

DIFFERENT  METALS  FOR  PLATING. — Silver  may  be  deposited 
upon  any  metal,  but  not  upon  all  with  equal  facility.  Copper, 
brass,  and  German  silver,  are  the  best  metals  to  plate ;  iron,  zinc, 
tin,  pewter,  and  Britannia  metal,  are  much  more  difficult ;  lead  is 
easier,  but  it  is  not  a  good  metal,  because  of  the  rapidity  with  which 
it  tarnishes,  and,  from  its  softness,  easily  yields  to  the  pressure  of 
the  burnisher:  nevertheless  all  these  metals  and  alloys  may  be, 


604  THE  PEACTICAL   METAL-WORKER'S  ASSISTANT. 

and  are,  plated,  but  cannot  give  the  satisfaction  which  brass,  cop- 
per, or  German  silver  afford.  In  plating  upon  alloys  having  tin 
in  them,  such  as  Britannia  metal,  they  must  not  be  dipped  into 
nitric  acid  previous  to  plating ;  but  into  a  hot  and  strong  solution 
of  caustic  potash  or  soda  for  five  minutes,  and  put  directly  into  the 
plating  solution  (which  should  have  an  excess  of  cyanide  of  potas- 
sium, and  the  battery  be  as  strong  as  the  liquor  will  admit  of  with- 
out gas  being  evolved),  until  covered,  when  the  silver  may  be 
thickened  by  an  ordinary  solution  and  battery. 

ELECTRICITY  GIVEN"  OFF  FROM  SANDY  DEPOSITS. — We  may 
mention  that  when  depositing  silver  upon  a  large  surface,  and  the 
solution  or  battery  being  in  the  condition  to  give  the  sandy  deposit, 
or  rather  when  the  deposit  has  gone  on  for  a  long  time  and  the 
solution  not  been  agitated,  so  that  it  has  become  very  much 
exhausted  of  silver  round  the  article,  the  deposit  towards  the  end 
of  the  time  has  been  almost  impalpable  to  the  touch,  like  flour : 
sometimes  the  grains  were  a  little  coarser.  The  practice,  in  such 
cases,  is  to  lift  the  articles  from  the  solution,  and  to  place  them  in 
boiling  water,  and  after  steeping  there  some  time,  to  take  them  out, 
when  the  heat  of  the  metal  soon  causes  it  to  dry.  Under  these 
circumstances,  when  the  deposit  was  of  the  sort  stated,  we  have 
seen  on  a  large  waiter  or  tray,  when  the  hand  was  rapidly  drawn 
over  the  surface,  after  it  was  dried  in  the  manner  described,  the 
same  effect  produced  as  when  the  hand  is  drawn  over  an  electrified 
handkerchief,  or  sheet  of  paper,  accompanied  with  a  crackling 
noise  and  pricking  sensation.  We  have  repeatedly  observed  these 
phenomena,  but  never  having  chanced  to  be  in  the  dark,  no  light 
was  visible  from  the  surface  rubbed.  Although  these  are  the  con- 
ditions under  which  the  observations  were  made,  the  phenomena 
were  not  produced  every  time  these  conditions  were  found.  It  is 
probably  caused  by  the  fact  that  this  kind  of  deposit,  which  is  of  a 
chalky  appearance,  is  a  bad  conductor  of  electricity,  and  as  the 
boiling  water  was  often  very  impure,  holding  salts  in  solution,  the 
rapid  evaporation  of  the  water  from  the  surface  of  this  sort  of 
deposit  might  leave  it  excited  for  a  short  time,  and  the  hand  being 
drawn  across  at  the  time  of  excitation,  the  electricity  was  liberated. 

THE  OLD  METHOD  OF  PLATING. — Many  objections  have  been 
urged  against  the  application  of  electro-deposition  to  the  purposes 
of  plating,  as  a  branch  of  manufacture,  either  as  a  competitor  or 
substitute  for  the  old  method,  technically  called  Sheffield  plate— so 
called  because  Sheffield  is  a  principal  seat  of  that  manufacture. 
To  enable  our  readers  to  form  a  proper  estimate  of  the  objections 
urged,  by  enabling  them  to  judge  of  the  relative  importance  and 
value  of  the  two  processes,  we  shall  add  a  brief  description  of  the 
old  method. 

An  ingot  of  copper  being  cast,  was  filed  square  and  smooth, 
and  a  piece  of  silver  was  placed  upon  it,  the  two  surfaces  being 
perfectly  clean:  a  little  borax  having  been  introduced  between  the 
two  metals,  they  were  bound  together  with  iron  wire,  and  then 


ELECTRO-PLATING.  605 

heated  in  a  furnace  nearly  to  the  melting  point ;  the  small  quan- 
tity of  borax  increased  the  fusibility  of  the  two  metals  at  their 
surface,  and  thus  they  were  fused  together.  When  fusion  was 
effected  the  metals  were  subjected  to  the  dilating  process  of  heavy 
rollers,  the  dimensions  in  length  and  width  being  regulated  accord- 
ing to  the  articles  to  be  made.  This  sheet  formed  the  base  or 
foundation  of  every  article,  of  whatever  shape  or  form,  and  how- 
ever it  was  to  be  ornamented  when  finished. 

To  produce  ornaments,  leaf  silver  was  stamped  in  iron  dies 
representing  the  ornaments  required,  which,  when  removed  from 
the  dies,  were  filled  with  an  alloy  of  lead  and  tin.  These  were 
then  soldered  upon  the  flat  or  shaped  plain  surface  with  soft 
solder,  which  melts  at  a  very  low  temperature :  thus  were  pro- 
duced the  silver  edges,  or  mounts. 

The  quality  of  the  ornament  depended  entirely  upon  the  price 
of  the  article  ;  but  whatever  the  quality,  all  ornaments  in  the  old 
mode  of  plating  were  thus  made,  the  only  difference  being  the 
thickness  of  the  silver  leaf  used : — Ornamental  feet,  handles,  knobs, 
etc.,  were  made  in  the  same  manner,  being  struck  up  in  two  parts, 
filled  with  lead  and  tin,  soldered  together  with  soft  solder,  and 
afterwards  soldered  to  the  main  body.  Articles  (such  as  table 
candlesticks)  which  would  be  too  heavy  if  filled  with  lead,  were 
filled  with  rosin,  pitch  or  any  other  similar  substance,  for  the  pur- 
pose of  preventing  the  article  being  flattened  by  pressure.  Hence 
it  is  evident  that  no  solid  article  could  be  made  by  the  old  mode  of 
plating,  the  only  way  of  producing  articles  being  to  work  them  up 
by  the  hammer,  or  to  strike  them  in  dies  from  a  flat  surface  :  and 
being  restricted  to  the  use  of  soft  solder,  on  account  of  the  plated 
metal  and  the  shells  of  silver,  forming  the  edges,  not  supporting 
the  required  heat  to  melt  silver  solder,  it  is  equally  evident  that 
the  joinings  so  constructed  would  be  easily  removed  either  by 
force  or  heat. 

The  nearest  approach  to  solid  articles  made  by  the  old  method 
of  plating,  were  forks  and  spoons :  these  were  generally  made  of 
iron,  thin  silver  being  soldered  upon  the  surface,  which  was  after- 
wards dressed  smooth,  and  polished. 

The  heat  used  in  this  operation  was  merely  that  of  an  ordinary 
soldering  iron;  because,  were  a  greater  heat  applied,  the  silver 
would  form  an  alloy  with  the  tin  and  lead  of  the  solder,  and  melt : 
the  same  heat  that  cemented  the  metals  in  the  first  instance  would 
be  sufficient  to  disunite  them ;  and  thus,  when  these  forks  were 
exposed  in  hot  gravy,  the  solder  was  liable  to  become  soft,  and 
the  silver  covering,  yielding  readily  to  the  knife,  to  peel  up  or 
become  abraided,  in  consequence  of  the  soft  intervening  metal. 

ADVANTAGES  OF  ELECTRO-PLATING. — The  advantages  offered 
to  the  plater  by  the  electro-process  are  many,  arising  from  the  fact 
of  the  articles  being  plated  after,  instead  of  before,  being  manufac- 
tured. This  at  once  entirely  removed  all  those  restrictions  on 
taste  and  design,  under  which  the  plater  was  forced,  by  the  nature 
of  his  process,  to  labor. 


606  THE   PRACTICAL   METAL-WOEKER'S  ASSISTANT. 

The  following  may  be  considered  some  of  the  principal  differ- 
ences existing  in  the  two  processes  of  plating — the  old  method 
and  the  electro-process : 

1.  The  electro-plater  ie  not  limited  in  the  use  of  the  metal  upon 
which  he  plates.     There  is  generally  used,  as  the  basis  of  all  elec- 
tro-plated goods,  a  hard  white  metal,  which  possesses  the  seund, 
and  approaches  very  nearly  to  the  color,  of  silver.     Inferior  goods 
are  sometimes  made  in  brass. 

2.  The  electro-plater  is  not  restricted  to  the  use  of  soft  solder, 
which  melts  at  a  very  low  temperature,  and  forms  a  very  insufficient 
joint,  besides  preventing  any  sound  or  ring  in  the  article  so  soldered. 
Where  cheap  goods  are  required,  this  may  be  used  in  this  process 
as  well  as  in  the  old,  but  is  always  open  to  the  same  objection. 
All  goods  of  superior  quality,  made  for  the  electro-process,  are 
soldered  with  what  is  termed  in  the  trade  hard  silver  solder,  com- 
posed of  2  parts  of  silver  and  1  part  of  brass  melted  together, 
which  is  not  affected  by  any  ordinary  degree  of  heat,  and  presents 
a  joint  as  strong  as  the  metal  itself. 

The  common  solder  of  braziers  may  also  be  used  with  advan- 
tage :  it  is  very  hard  and  durable  and  requires  a  strong  heat  to 
melt  it. 

3.  The  electro-plater,  in  producing  ornamental  articles,  is  not 
obliged  to  incur  the  expense  of  cutting  iron  dies  for  every  minute 
portion  ;  being  under  no  restriction,  he  models  his  pattern,  and  by 
casting  and  chasing  in  solid  metal,  produces  an  exact  copy,  which 
is  afterwards  plated  or  gilt. 

Thus  any  pattern  which  can  be  executed  in  silver  may  be  readily 
made  in  plate  by  this  method. 

4.  The  junction  of  the  plating  with  the  metal  below,  by  the 
electro-process,  is  perfect,  without  the  presence  of  any  intervening 
substance :  the  forks  and  spoons  thus  made  are  not  open  to  the 
objection  of  the  old  process,  and  are  found  to  answer  all  the  pur- 
poses of  silver,  in  sound,  appearance,  and  wear :  they  are  generally 
tested,  previously  to  polishing,  by  exposure  in  a  furnace  to  a  red  heat. 

5.  From  the  facility  with  which  old  goods  may  be  now  restored, 
these  goods  bear  an  intrinsic  value  ;  whereas  before  the  introduc- 
tion of  the  electro-process,  a  plated  article  worn  through  in  any 
part  was  valueless. 

OBJECTIONS  TO  ELECTRO-PLATING.— Several  objections  to  the 
electro-process  have  been  keenly  urged ;  but  they  may  all  'be  re- 
duced to  the  following : 

1st  objection :  Deposited  metal  is  crystalline,  and  therefore, 
though  it  may  impart  in  appearance  a  silver  coating,  it  must  neces- 
sarily be  full  of  minute  interstices  between  the  crystals :  hence 
when  a  metal,  such  as  copper,  is  plated,  it  is  liable  to  be  acted  upon 
by  the  atmosphere,  or  injured  by  whatever  is  brought  into  contact 
with  it. 

This  objection  was  not  without  foundation,  as  all  deposited 
metals  are  crystalline  in  texture,  but  they  do  not  necessarily  leave 


j7"J  ELECTRO-PLATING.  607 

interstices ;  the  objection,  however,  is  almost  entirely  removed  by 
keeping  the  articles  in  motion  during  the  deposition :  by  motion 
and  proper  arrangement  of  battery  we  have  deposited  silver  of  as 
high  specific  gravity  as  hammered  silver,  which  could  not  be  the 
case  if  it  were  porous. 

2d  objection :  As  only  pure  silver  is  deposited,  it  must  necessarily 
be  soft,  and  consequently  liable  to  abrasion,  and  more  rapid  wear. 

This  objection  is  also  partly  true.  Only  pure  silver  can  be 
deposited;  but  it  is  not  necessarily  soft:  the  quality  of  the  deposit, 
in  this  respect,  depends  (as  already  noticed)  a  great  deal  upon  the 
nature  of  the  solution  and  the  battery  power.  Intensity  of  battery 
gives  hardness  to  the  metal  deposited.  There  is  no  complaint 
more  common  amongst  the  burnishers  of  electro-plated  articles, 
than  that  the  metal  is  hard ;  and  it  is  far  from  being  an  uncommon 
occurrence,  that  some  goods  have  to  be  heated  so  that  they  may  be 
more  easily  burnished  or  polished.  How  far  this  annealing  may 
affect  the  wear  of  the  goods  is  not  yet  ascertained.  That  the  silver 
is  pure  we  think  an  advantage — hence  the  superior  color  which 
electro-plated  goods  possess :  besides  which,  purchasers  are  not 
subject  to  the  risk  of  having  a  plate  much  alloyed. 

3d  objection :  The  mounts  or  prominences  of  articles,  which 
must  have  the  greatest  wear,  have  the  least  and  thinnest  deposit. 

This  objection  is  entirely  without  foundation,  as  the  prominences 
have  always  the  greatest  portion  of  deposit,  and  the  hollow  parts 
the  least. 

SOLID  SILVER  ARTICLES  MADE  BY  THE  BATTERY. — Silver  may 
be  deposited  from  its  cyanide  solution  upon  wax  moulds  polished 
with  black  lead,  almost  as  easily  as  copper ;  but  for  this  purpose 
it  is  better  to  have  the  solution  much  stronger  in  silver  than  for 
plating.  We  have  found  that  8  ounces  of  silver  to  the  gallon  of 
solution  make  a  very  good  strength.  Nevertheless,  no  articles  are 
made  in  silver  by  depositing  upon  wax  in  this  manner.  Strong 
solutions  of  cyanide  of  potassium  and  silver  act  upon  wax,  and 
would  soon  destroy  a  mould.  The  method  of  making  articles  in 
solid  silver  by  the  electro-process  has  been  already  explained  (page 
544,)  namely,  a  copper  mould  is  made  by  the  electrotype,  and  the 
silver  is  deposited  within  this  mould  to  the  proper  thickness  ;  after 
which  it  is  kept  in  a  hot  solution  of  crocus  and  muriatic  acid,  or 
boiled  in  dilute  hydrochloric  acid,  which  dissolves  the  copper  with- 
out injuring  the  silver. 

The  method  which  we  esteem  as  best  for  dissolving  off  the  cop- 
per is  this :  an  iron  solution  is  first  made  by  dissolving  a  quantity 
of  copperas  in  water,  placing  it  on  a  fire  till  it  begins  to  boil :  a 
little  nitric  acid  is  then  added — nitrates  of  potash  and  soda  will  do 
just  as  well — the  iron,  which  is  thus  peroxidized,  may  be  precipi- 
tated cither  by  ammonia,  or  carbonate  of  soda;  the  precipitate 
being  washed,  muriatic  acid  is  added  till  the  oxide  of  iron  is  dis- 
solved. This  forms  the  solution  for  dissolving  the  copper.  When 
the  solution  becomes  almost  colorless,  and  has  ceased  to  act  on  the 


608  THE  PRACTICAL   METAL-WORKER'S  ASSISTANT^ 

copper, -the  addition  of  a  little  ammonia  will  precipitate  the  iron 
again ;  after  a  little  exposure,  the  copper  remains  in  solution,  which 
is  decanted  off  and  preserved  for  recovering  the  copper ;  this  is 
done  by  neutralizing  the  ammonia  by  an  acid,  and  putting  in  pieces 
of  iron,  which  deposit  the  copper  in  the  metallic  state.  The  pre- 
cipitate of  iron  is  again  dissolved  in  muriatic  acid,  and  employed 
in  dissolving  the  copper.  Thus  the  iron  may  be  used  over  and 
over  again  with  little  trouble,  and  the  persalt  of  iron  will  be  found 
to  dissolve  the  copper  more  rapidly  than  an  acid ;  persulphate  of 
iron  must  not  be  used,  as  it  dissolves  the  silver  along  with  the  cop- 
per. The  silver  article  is  then  cleaned  in  the  usual  way  (page  593), 
and  heated  to  redness  over  a  clear  charcoal  fire,  which  gives  it  the 
appearance  of  dead  silver,  in  which  state  it  may  be  kept,  or,  if 
desired,  it  may  be  scratched  and  burnished. 

When  ammonia  is  first  added  to  the  above  solution  of  copper 
and  iron,  both  these  metals  are  precipitated  together  as  a  brown 
precipitate.  After  a  little  exposure,  the  copper  dissolves,  and  the 
iro'n  is  at  the  same  time  peroxidized,  having  been  previously 
reduced  to  the  protoxide  by  the  copper  dissolving.  When  the 
persulphate  of  iron  is  used  for  dissolving  copper,  and  ammonia  is 
then  added  to  the  solution,  the  same  results  take  place : — the  pre- 
cipitation of  both  copper  and  iron.  But  the  compound  seems  not 
so  stable,  the  copper  passing  more  quickly  into  an  oxide,  which 
dissolves  in  the  ammonia.  However,  with  free  ammonia,  either 
with  the  chloride  or  sulphate,  the  oxidation  of  the  metals  is  slower 
than  with  water  alone. 

Copper  moulds  intended  for  receiving  a  deposit  must  be  pro- 
tected on  the  back,  but  if  the  solution  is  very  strong,  there  is  every 
danger  that  it  will  decompose  the  protecting  substance,  thus  ren- 
dering the  solution  very  dirty,  and  causing  a  sediment.  For  the 
purpose  of  protecting  the  mould,  various  suggestions  and  experi- 
ments have  been  made ;  amongst  other  substances,  pitch  has  been 
tried:  it  is  easily  affected  alone,  but  on  boiling  a  little  of  it  in  pot- 
ash, a  heavy  and  dirty  sediment  is  left,  destitute  of  any  adhesive 
property ;  on  putting  a  quantity  of  this  sediment  into  a  pot  nearly 
filled  with  melted  pitch,  a  violent  effervescence  will  take  place,  set- 
ting free  a  volume  of  white  fumes  having  a  creosotic  smell.  After 
all  effervescence  has  ceased,  which  will  not  be  before  a  considerable 
time,  and  when  all  the  mass  seems  to  have  been  acted  upon,  the 
process  of  making  an  excellent  protecting  coating  is  completed— a 
coating  which  will  not  yield  in  the  solution,  and  which  is  at  once 
both  good  and  cheap,  its  only  fault  being  its  brittleness. 

In  the  manufacture  of  solid  silver  articles,  the  electro-process 
has  not  yet  been  of  extensive  application :  and  in  making  dupli- 
cates of  rare  objects  of  art,  and  costly  chased  or  engraved  articles 
in  silver,  one  prevailing  objection  has  been  felt,  namely,  they  have 
no  "ring,"  and  seem,  when  laid  suddenly  upon  a  table,  to  be 
cracked  or  unsound,  or  like  so  much  lead;  this  disadvantage  is  no 
doubt  partly  owed  to  the  crystalline  character  of  the  deposit,  and 


ELECTRO-PLATING.  609 

partly  to  the  pure  character  of  the  silver,  in  which  state  it  has  not 
a  sound  like  standard  or  alloyed  silver.  That  this  latter  cause  is 
the  principal  one,  appears  from  the  fact  that  a  piece  of  silver  thus 
deposited  is  not  much  improved  in  sound  by  being  heated  and 
hammered,  which  would  destroy  all  crystallization. 

We  may  mention  that  the  same  objections  are  applicable  to 
articles  made  in  gold  by  the  electro-deposit;  nevertheless,  for  fig- 
ures and  ornaments,  these  objections  are  of  little  weight.  When 
in  Marlborough  House  a  few  months  back,  we  were  shown  a  plate 
of  antique  pattern  in  deposited  silver,  which  was  all  but  free  from 
these  defects. 

DEAD  SILVERING  FOE  MEDALS. — The  perfect  smoothness  which  a 
medal  generally  possesses  on  the  surface,  renders  it  very  difficult  to 
obtain  a  coating  of  dead  silver  upon  it,  having  the  beautiful  silky 
lustre  which  characterizes  that  kind  of  work,  except  by  giving  it  a 
very  thick  coating  of  silver,  which  takes  away  the  sharpness  of  the 
impression.  This  dead  appearance  can  be  easily  obtained  by  put- 
ting the  medal,  previous  to  silvering,  in  a  solution  of  copper,  and 
depositing  upon  it,  by  means  of  a  weak  current,  a  mere  blush  of  cop- 
per, which  gives  the  face  of  the  medal  that  beautiful  crystalline  rich- 
ness that  deposited  copper  is  known  to  give.  The  medal  is  then 
to  be  washed  from  the  copper  solution,  and  immediately  to  be  put 
into  the  silver  solution.  A  very  slight  coating  of  silver  will  suffice 
to  give  the  dead  frosty  lustre  so  much  admired,  and  in  general  so 
difficult  to  obtain. 

OXIDIZING  SILVER. — A  very  beautiful  effect  is  produced  upon 
the  surface  of  silver  articles  technically  termed  oxidizing,  which 
gives  the  surface  an  appearance  of  polished  steel.  This  can  be. 
easily  effected  by  taking  a  little  chloride  of  platinum,  prepared  as 
described  at  page  527,  heating  the  solution  and  applying  it  to  the 
silver  when  an  oxidized  surface  is  required,  and  allowing  the  solu- 
tion to  dry  upon  the  silver.  The  darkness  of  the  color  produced 
varies  according  to  the  strength  of  the  platinum  solution,  from  a 
light  steel  gray  to  nearly  black.  The  effects  of  this  process,  when 
done  along  with  what  is  termed  dead  work,  is  very  pretty,  and  may 
be  easily  applied  to  medals,  giving  scope  for  the  exercise  of  taste. 
Upon  this  we  quote  the  following : 

"The  high  appreciation  in  which  ornaments  in  oxidized  silver 
are  now  held,  render  a  notice  of  the  process  followed  interesting. 
There  are  two  distinct  shades  in  use,  one  produced  by  chloride, 
which  has  a  brownish  tint,  and  the  other  by  sulphur,  which  has  » 
bluish  black  tint.  To  produce  the  former,  it  is  only  necessary  to 
wash  the  article  with  a  solution  of  sal-ammoniac ;  a  much  more 
beautiful  tint  may,  however,  be  obtained  by  employing  a  solution 
composed  of  equal  parts  of  sulphate  of  copper  and  sal-ammoniac 
in  vinegar.  The  fine  black  tint  may  be  produced  by  a  slightly- 
warm  solution  of  sulphuret  of  potassium  or  sodium." — C/iem.  Teclm. 
Mittheilunyen  von  Dr.Ellsner. 

PROTECTION  OF  SILVKB  SURFACE. — All  silver  or  plated  articles 
39 


610  THE   PRACTICAL    METAL-WORKER'S   ASSISTANT. 

are  subject  to  tarnish  by  exposure  to  the  air,  especially  in  this  cli- 
mate, and  where  coals  containing  so  much  sulphur  are  used ;  the 
tarnish  being  generally  a  sulphuret  of  silver.  Deposited  silver  is 
more  easily  tarnished  than  standard  silver. 

Medals  or  figures  silvered  for  the  sake  of  their  appearance  ought 
to  be  protected  from  the  air,  or  they  very  soon  lose  their  silver 
color ;  a  medal  may  be  put  into  a  frame  air-tight,  and  a  figure 
should  be  covered  with  a  glass  shade :  if  the  silver  has  been  left 
dead,  any  attempt  to  clean  it  destroys  its  appearance.  Varnishes 
have  been  tried  to  protect  the  silver  from  the  atmosphere ;  but  all 
varnishes,  however  colorless,  detract  from  the  silver  lustre,  and  are 
not  good.  For  ordinary  purposes,  medals  may  be  very  conve- 
niently protected  by  laying  a  piece  of  common  glass  over  the  sur- 
face, cut  to  the  exact  size,  and  held  close  by  a  piece  of  paper  pasted 
round  the  edges  of  both,  and  then  a  stout  piece  on  the  back.  We 
have  had  silver  medals,  preserved  by  this  means,  for  more  than  ten 
years.  Little  round  medals  may  be  conveniently  covered  by  Watch- 
glasses,  fastened  on  in  the  same  manner. 

CLEANING  OF  SILVER. — A  weak  solution  of  cyanide  of  potassium, 
used  as  a  wash  over  tarnished  silver,  will  brighten  it.  This  solu- 
tion was,  and  we  believe  is  still,  sold  in  small  bottles  for  this  pur- 
pose, but  it  is  not  good,  as  it  dissolves  the  silver  rapidly,  and  is 
such  a  deadly  poison  that  it  must  be  used  with  great  caution  on 
articles  that  may  be  required  for  domestic  purposes. 

A  variety  of  cleaning  pastes  and  powders  are  used  for  silver  or 
plated  goods.  Those  containing  mercury  and  oxide  of  lead  should 
be  avoided,  for  although  they  give  a  dark  color  when  newly  put 
on,  it  soon  blackens.  The  best  paste  we  have  found  is  a  mixture 
of  fine  precipitated  chalk,  carbonate  of  magnesia,  and  oxide  of  iron. 
These  materials  are  made  into  a  paste,  and  rubbed  upon  the  plate 
with  soft  leather:  for  wrought  or  chased  surfaces  a  hard  brush  is 
best.  The  goods  should  be  finished  by  polishing  with  leather  and 
a  little  of  this  mixture  in  a  dry  state,  which  will  give  that  fine  dark 
mirror-looking  color  so  much  admired.  Common  coarse  whiting 
and  flannel  cloths  should  not  be  used,  as  thev  wear  the  silver 
rapidly. 


CHAPTER  XXXI. ' 

ELECTRO-GILDING. 

THE  operation  of  gilding,  or  covering  other  metals  with  a  coat- 
ing of  gold,  is  performed  in  the  same  manner  as  the  operation  of 
plating,  with  the  exception  of  a  few  practical  modifications,  which 
we  shall  now  notice  in  detail. 

PREPARATION  OF  SOLUTION  OF  GOLD. — The  gold  solution  for 


ELECTRO-GILDING.  611 

gilding  is  prepared  by  dissolving  gold  in  three  parts  of  muriatic 
acid  and  one  of  nitric  acid,  which  forms  the  chloride  of  gold. 
This  is  digested  with  calcined  magnesia,  and  the  gold  is  precipi- 
tated as  an  oxide.  The  oxide  is  boiled  in  strong  nitric  acid,  which 
dissolves  any  magnesia  in  union  with  it:  the  oxide  being  well 
washed  is  dissolved  in  cyanide  of  potassium,  which  gives  cyanide 
of  gold  and  potassium ;  thus : — 

Substances  used:  Substances  produced: 


Oxide  of  Gold  =  AuO 

2.  Cyanide  of  Potassium=2KCy 


Cyanide  of  Gold  \ 
and  Potassium  i 


Potash  =KO 

Auo -I- 2  KCy=KO-f  (KCy+AuCy.) 

By  this  method  a  proportion  of  potash  is  formed  in  the  solution, 
as  an  impurity  ;  it  is  not,  however,  very  detrimental  to  the  process. 
In  preparing  the  oxide  of  gold  there  is  always  a  little  of  the  gold 
lost,  to  recover  which  the  washings  should  be  kept,  evaporated  to 
dryness,  and  fused. 

Another  and  very  simple  method  is  this  : — Add  a  solution  of 
cyanide  of  potassium  to  the  chloride  of  gold  until  all  the  precipi- 
tate is  redissolved ;  but  this  gives  chloride  of  potassium  in  the  so- 
lution, which  is  not  good.  In  the  preparation  of  the  solution  by 
this  means  there  are  some  interesting  reactions.  As  the  chloride 
of  gold  has  always  an  excess  of  acid,  the  addition  of  cyanide  of 
potassium  causes  violent  effervescence,  and  no  precipitate  of  gold 
takes  place  until  all  the  free  acid  is  neutralized,  which  causes  a 
considerable  loss  to  the  cyanide  of  potassium.  There  is  always 
formed  in  this  deposition  a  quantity  of  ammonia  and  carbonic  acid, 
from  the  deposition  of  the  cyanate  of  potash ;  and  if  tne  chloride 
of  gold  be  recently  prepared  and  hot,  there  is  often  formed  some 
aurate  of  ammonia  (fulminate  of  gold),  which  precipitates  with  the 
cyanide  of  gold.  Were  this  precipitate  to  be  collected  and  dried, 
it  would  explode  when  slightly  heated.  On  previously  diluting 
the  chloride  of  gold,  or  using  it  cold,  this  compound  is  not  formed. 

After  the  free  acid  is  neutralized  by  the  potash,  further  addition 
of  the  cyanide  of  potassium  precipitates  the  gold  as  cyanide  of 
gold,  having  a  light  yellow  color ;  but  as  this  is  slightly  soluble  in 
ammonia  and  some  of  the  alkaline  salts,  it  is  not  advisable  to  wash 
the  precipitate  lest  there  be  a  loss  of  gold.  Cyanide  of  potassium 
is  generally  added  until  the  precipitate  is  redissolved;  conse- 
quently much  impurity  is  formed  in  the  solution,  namely,  ni- 
trate and  carbonate  of  potash  with  chloride  of  potassium  and 
ammonia.  Notwithstanding,  this  solution  works  very  well  for 
a  short  time,  and  it  is  very  good  for  operations  on  a  small 
scale. 

BATTERY  PROCESS  OF  PREPARING  GOLD  SOLUTION. — The  best 
method  of  preparing  the  gold  solution  is  that  described  for  silver 
(p.  589).  Say  the  operator  wishes  to  prepare  a  gallon  of  gold  so- 


612  THE  PRACTICAL   METAL-WORKER'S   ASSISTANT. 

lution,  he  dissolves  four  ounces  of  cyanide  of  potassium  in  one 
gallon  of  water,  and  heats  the  solution  to  150°  Fah. ;  he  now  takes 
a  small  porous  cell  and  fills  it  with  this  cyanide  solution,  and  places 
it  inside  the  gallon  of  solution  :  into  this  cell  is  put  a  small  plate 
of  iron  or  copper,  and  attached  by  a  wire  to  the  zinc  of  a  battery. 
A  piece  of  gold  is  placed  into  the  large  solution,  facing  the  plate 
in  the  porous  cell,  and  attached  to  the  copper  of  the  battery.  The 
whole  is  allowed  to  remain  in  action  until  the  gold,  which  is  to  be 
taken  out  from  time  to  time  and  weighed,  has  lost  the  quantity  re- 
quired in  solution.  By  this  means  a  solution  of  any  strength  can 
be  made,  according  to  the  time  allowed.  The  solution  in  the 
porous  cell,  except  the  action  has  continued  long,  will  have  no 
gold,  and  may  be  thrown  away.  Half  an  hour  will  suffice  for  a 
small  quantity  of  solution — of  course  any  quantity  of  solution 
may  be  made  up  by  the  same  means.  For  all  the  operations  of 
gilding  by  the  cyanide  solution,  it  must  be  heated  to  at  least  130° 
Fah.  The  articles  to  be  gilt  are  cleaned  in  the  way  described  for 
silver,  but  are  not  dipped  into  nitric  acid  previously  to  being  put 
in  the  gold  solution.  Three  or  four  minutes  is  sufficient  time  to 
gild  any  small  article.  After  the  articles  are  cleaned  and  dried 
they  are  weighed — and  when  gilt  they  are  weighed  again ;  thus 
the  quantity  of  gold  deposited  is  ascertained.  Any  convenient 
means  may  be  adopted  for  heating  the  solution.  The  one  generally 
adopted  is  to  put  a  stoneware  pan  containing  the  solution  into  an 
iron  or  tinplate  vessel  filled  with  water,  which  is  kept  at  the  boil- 
ing point  either  by  being  placed  upon  a  hot  plate  or  over  gas. 
The  hotter  the  solution  the  less  battery  power  is  required.  Gen- 
erally three  or  four  pairs  of  plates  are  used  for  gilding,  and  the 
solution  is  kept  at  130°  to  150°  Fah.  But  one  pair  will  answer 
if  the  solution  is  heated  to  200°. 

PROCESS  OF  GILDING. — The  process  of  gilding  is  generally  per- 
formed upon  silver  articles.  The  method  of  proceeding  is  as  fol- 
lows :  When  the  articles  are  cleaned  as  described  in  our  chapter 
on  plating,  they  are  weighed,  and  well  scratched  with  wire  brushes, 
which  cleanse  away  any  tarnish  from  the  surface,  and  prevents  the 
formation  of  air-bubbles.  They  are  then  kept  in  clean  water  until 
it  is  ^  convenient  to  immerse  them  in  the  gold  solution.  One  im- 
mersion is  then  given,  which  merely  imparts  a  blush  of  gold ; 
they  are  taken  out  and  again  brushed ;  they  are  then  put  back  into 
the  solution  and  kept  there  for  three  or  four  minutes,  which  will 
be  sufficient  if  the  solution  and  battery  are  in  good  condition ;  but 
the^  length  of  time  necessarily  depends  on  these  two  conditions, 
which  must  be  studied  and  regulated  by  the  operator. 

Iron,  tin,  and  lead,  are  very  difficult  to  gild  direct ;  they  there- 
fore generally  have  a  thin  coating  of  copper  deposited  upon  them 
by  the  cyanide  of  copper  solution  and  immediately  put  into  the 
gilding  solution. 

CONDITIONS  REQUIRED  IN  GILDING.— The  gilding  solution  gen- 
erally contains  from  one-half  to  an  ounce  of  gold  in  the  gallon,  but 


ELECTRO-GILDING.  613 

for  covering  small  articles,  such  as  medals,  for  tinging  daguerreo- 
types, gilding  rings,  thimbles,  etc.,  a  weaker  solution  will  do.  The 
solution  should  be  sufficient  in  quantity  to  gild  the  articles  at  once, 
so  that  it  should  not  have  to  be  done  bit  by  bit ;  for  when  there  is 
a  part  in  the  solution  and  a  part  out,  there  will  generally  be  a  line 
mark  at  the  point  touching  the  surface  of  the  solution.  The 
rapidity  with  which  metals  are  acted  upon  at  the  surface  line  of  the 
solution  is  remarkable.  If  the  positive  electrode  is  not  wholly 
immersed  in  the  solution,  it  will,  in  a  short  time,  be  cut  through 
at  the  surface  of  the  water,  as  if  cut  by  a  knife.  This  is  also 
the  case  in  silver,  copper,  and  other  solutions,  as  before  referred  to. 

MAINTAINING  THE  GOLD  SOLUTION. — As  the  gold  solution 
evaporates  by  being  hot,  distilled  water  must  from  time  to  time  be 
added.  The  water  should  always  be  added  when  the  operation 
of  gilding  is  over,  not  when  it  is  about  to  be  commenced,  or  the 
solution"  will  not  give  so  satisfactory  a  result.  When  the  gilding 
operation  is  continued  successively  for  several  days,  the  water 
should  be  added  at  night.  The  average  cost  of  depositing  gold  is 
about  4  cts.  per  pennyweight. 

The  means  of  testing  the  free  cyanide  of  potassium,  with  nitrate 
of  silver,  as  described  for  silver,  is  not  applicable  to  the  gold  solu- 
tion ;  but  it  may  be  tested  by  the  ammoniuret  of  copper,  see  p.  603. 
To  obtain  a  deposit  of  a  good  color  much  depends  upon  the  state 
of  the  solution  and  battery ;  it  is  therefore  necessary  that  strict 
attention  be  paid  to  these,  and  more  so  as  the  gold  solution  is  very 
liable  to  change  if  the  relative  size  of  the  article  receiving  the 
deposit  is  not  according  to  that  of  the  positive  plate. 

The  result  of  a  series  of  observations  and  experiments,  con- 
tinued daily  throughout  a  period  of  nine  months,  showed  that  in 
five  instances  only  the  deposit  was  exactly  equal  to  the  quantity 
dissolved  from  the  positive  plate.  In  many  cases  the  difference 
did  not  exceed  3  per  cent.,  though  occasionally  it  rose  to  50  per  cent. 
The  average  difference  however  was  25  per  cent.  In  some  cases 
double  the  quantity  dissolved  was  deposited,  in  others  the  reverse 
occurred — both  resulting  from  alterations  made  in  the  respective 
processes ;  for  in  these  experiments  we  varied,  as  far  as  practicable, 
the  state  of  the  solution  and  the  relative  sizes  of  the  negative  and 
positive  electrodes. 

The  most  simple  method  of  keeping  a  constant  register  of  the 
state  of  the  solution  is  to  weigh  the  gold  electrode  before  putting 
it  into  the  solution ;  and,  when  taking  it  out,  to  compare  the  loss 
with  the  amount  deposited :  a  little  allowance,  however,  must  be 
made  for  small  portions  of  metal  dissolved  in  the  solution,  from 
the  articles  that  are  gilt,  which,  when  gilding  is  performed  daily, 
is  considerable  in  a  year.  A  constant  control  can  thus  be  exer- 
cised over  the  solution,  to  which  there  will  have  to  bo  added  from 
time  to  time  a  little  cyanide  of  potassium,  a  simple  test  of  require- 
ment being  that  the  gold  pole  should  always  come  out  clean — for 
if  it  has  a  film  or  crust  it  is  a  certain  indication  that  the  solution 


614  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

is  deficient  of  cyanide  of  potassium.  Care  must  be  taken  to  dis- 
tinguish this  crust,  which  is  occasionally  dark-green  or  black,  from 
a  black  appearance  which  the  gold  pole  will  take  when  very  small 
in  comparison  to  the  article  being  gilt,  and  which  is  caused  by 
the  tendency  to  evolve  gas.  In  this  case  an  addition  of  cyanide 
of  potassium  would  increase  the  evil.  The  black  appearance  from 
the  tendency  to  the  escape  of  gas  has  a  slimy  appearance.  This 
generally  takes  place  when  the  solution  is  nearly  exhausted  of 
gold,  of  which  fact  this  appearance,  taken  conjointly  with  the  rela- 
tive sizes  of  the  electrodes,  are  a  sure  guide. 

To  REGULATE  THE  COLOR  OF  THE  GILDING. — The  gold  upon 
the  gilt  article,  on  coming  out  of  the  solution  should  be  of  a  dark- 
yellow  color,  approaching  to  brown,  but  this  when  scratched  will 
yield  a  beautifully-rich  deep  gold.  If  the  color  is  blackish  it 
ought  not  to  be  finished,  for  it  will  never  either  brush  or  burnish 
a  good  color.  If  the  battery  is  too  strong,  and  gas  is  given  oft' 
from  the  article,  the  color  will  be  black ;  if  the  solution  is  too 
cold,  or  the  battery  rather  weak,  the  gold  will  be  light-colored ; 
so  that  every  variety  of  shade  may  be  imparted.  A  very  rich  dead 
gild  may  be  made  by  adding  ammoniuret  of  gold  to  the  solution 
just  as  the  articles  are  being  put  in,  or  what  is  better,  add  some 
sulphuret  of  carbon  in  the  same  way  as  for  silver  solutions,  which 
affects  the  color  and  appearance  of  the  gold  in  the  same  way  as  it 
does  the  silver. 

COLORING  OF  GILDING. — A  defective  colored  gilding  may  be  im- 
proved by  the  same  method  as  that  adopted  in  the  old  process  to 
color  gilding  or  gold,  namely,  by  the  help  of  the  following  mixture : 

3  parts  Nitrate  of  Potash 
li  Alum 

1J  Sulphate  of  Zinc 
1^  Common  Salt. 

These  ingredients  are  put  into  a  small  quantity  of  water,  to  form 
a  sort  of  paste,  which  is  put  upon  the  articles  to  be  colored :  they 
are  then  placed  upon  an  iron  plate  over  a  clear  fire,  so  that  they  will 
attain  nearly  to  a  black  heat,  when  they  are  suddenly  plunged  into 
cold  water :  this  gives  them  a  beautiful  high  color.  Different  hues 
may  be  had  by  a  variation  in  the  mixture. 

To  DISSOLVE  GOLD  FROM  GILT  ARTICLES.— Before  regilding 
articles  which  are  partly  covered  with  gold,  or  when  the  gilding  'is 
imperfect,  and  the  articles  require  regilding,  the  gold  should  be 
removed  from  them  by  putting  them  into  strong  nitric  acid ;  and 
when  the  articles  have  been  placed  in  the  acid,  by  adding  some 
common  salt,  not  in  solution,  but  in  crystals.  By  this  method  gold 
may  be  dissolved  from  any  metal,  even  from  iron,  without  injuring 
it  in  the  least.  After  coming  out  of  the  acid,  the  articles  must  be 
polished.  The  best  method,  however,  is  to  brush  off  the  gold  as 
described  for  silver  (page  597),  which  gives  the  polish  at  the  same 
time. 


ELECTRO-GILDING.  615 

To  RECOVER  THE  GOLD. — When  the  gold  is  dissolved  off  by  the 
acid  after  it  is  saturated,  or  when  it  ceases  to  dissolve  the  gold 
rapidly,  the  acid  is  diluted  with  several  times  its  bulk  of  water, 
und  then  soda  or  potash  added  till  the  greater  portion  of  the  acid 
is  neutralized.  A  solution  of  sulphate  of  iron  (copperas)  is  then 
added,  so  long  as  a  precipitate  is  formed ;  when  this  settles  down 
it  is  carefully  collected  upon  a  paper  filter,  washed  and  dried,  and 
then  fused  in  a  crucible  with  a  little  borax  and  common  salt,  when 
the  gold  is  found  as  a  button  at  the  bottom  of  the  crucible. 

When  the  gold  is  brushed  off)  the  brushings  are  burned  at  a  red 
heat,  and  the  residue  fused  with  carbonate  of  soda  and  a  little 
borax:  in  this  case,  the  gold  will  not  be  pure  and  will  have  to  be 
refined. 

OBJECTIONS  TO  ELECTRO-GILDING.— Objections  have  also  been 
made  to  the  application  of  electro-gilding  to  the  arts,  of  the  same 
kind  as  those  urged  against  electro-plating ;  but  the  now  almost 
universal  adoption  of  this  process  by  gilders,  because  of  the  perfec- 
tion to  which  the  articles  are  brought,  forms  the  best  answer  we 
can  give  to  such  objections.  However,  let  us  take  a  hasty  glance 
at  the  old  process  and  its  consequences,  that  we  may  be  enabled 
to  judge  of  the  comparative  merits  of  both  methods. 

Before  the  introduction  of  electro-deposition,  the  only  method  of 
gilding  was  by  forming  an  amalgam  of  gold  and  mercury,  which, 
at  the  consistence  of  a  thin  paste,  was  brushed  upon  the  articles 
over  a  strong  heat ;  the  mercury  being  gradually  dissipated,  the 
gold  remained  fixed  upon  the  articles.  This  process  is  most  per- 
nicious, and  destructive  to  human  life ;  the  mercury,  volatilized  by 
the  heat,  insinuates  itself  into  the  bodies  of  the  workmen,  notwith- 
standing the  greatest  care ;  and  those  who  are  so  fortunate  as  to 
escape  for  a  time  absolute  disease,  are  constantly  liable  to  saliva- 
tion from  its  effects.  Paralysis  is  common  among  them,  and  the 
average  of  their  lives  is  very  short ;  it  has  been  estimated  as  not 
exceeding  35  years.  It  is  difficult  to  believe  that  men  could  be 
found  to  engage  in  such  a  busrhess,  reckless  of  the  consequences  so 
fearfully  exhibited  before  them;  and  it  would  naturally  be  thought 
they  would  hail  with  pleasure  the  introduction  of  any  process 
which  would  be  put  a  stop  to  such  a  dreadful  sacrifice  of  human 
life.  But  it  is  very  difficult  to  overcome  interest  and  prejudice, 
even  when  the  object  to  be  gained  is  of  such  vast  importance. 

EFFECTS  OF  CYANOGEN  ON  HEALTH. — The  effects  produced 
upon  the  health  of  those  who  work  constantly  over  cyanide  solu- 
tions are  not  yet  fully  tested,  by  which  we  could  form  a  compari- 
son with  the  old  process;  for  every  new  trade,  or  operation,  gives 
rise  to  a  new  disease,  or  some  new  forms  of  an  old  disease.  Hav- 
ing ourselves  inhaled  much  of  the  fumes  of  that  "ominoua"  g;us 
given  off  from  the  cyanide  of  potassium  solution,  we  are  not  pre- 
pared to  stand  its  advocate,  but  would  rather  warn  all  employed  at 
the  business,  or  who  may  in  any  degree  have  to  do  with  these  so- 
lutions, to  be  very  careful  not  to  use  too  much  freedom.  The 


616  *  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

hands  of  those  engaged  in  gilding  or  plating  are  subjected  to  uloera- 
tion,  particularly  if  they  have  been  immersed  in  the  solution.  The 
ulcers  are  not  only  annoying  but  painful;  and,  on  their  first  appear- 
ance, if  care  is  not  properly  taken  to  wash  them  in  strong  cyanide 
of  potassium,  and  then  in  acid  water,  the  operator  will,  in  a  short 
time,  have  to  take  a  few  days  rest.  We  have  repeatedly  seen,  by 
the  aid  of  a  magnifying  glass,  gold  and  silver  reduced  in  these 
ulcerations.  We  have  also  known  of  eruptions  breaking  out  over 
the  bodies  of  workmen  after  inhaling  those  deleterious  fumes 
when  they  were  very  bad,  as  when  solutions  were  precipitated  by 
acids  or  being  evaporated  to  dryness  in  a  close  apartment  for  the 
recovery  of  the  metal.  Eepeatedly  have  we  seen  the  legs  of  work- 
men thus  afflicted,  and  always  after  they  have  been  exposed  to 
extra  fumes' 

The  following  statement  of  the  general  effects  of  electro-plating 
and  gilding  on  the  health  of  those  engaged  in  them,  as  experienced 
by  ourselves  and  others,  may  not  be  uninteresting  to  our  readers : 
but  it  is  necessary  to  premise  that  the  apartments  in  which  we 
were  employed  were  improperly  ventilated. 

The  gas  has  a  heavy  sickening  smell,  and  gives  to  the  mouth  a 
saline  taste,  and  scarcity  of  saliva ;  the  saliva  secreted  is  frothy. 
The  nose  becomes  dry  and  itchy,  and  small  pimples  are  found 
within  the  nostrils,  which  are  very  painful  (we  have  felt  these 
effects  in  the  nose  from  the  hydrogen  of  the  batteries,  where  there 
were  no  cyanide  solutions).  Then  follows  a  general  languor  of 
body;  disinclination  to  take  food,  and  a  want  of  relish.  After 
being  in  this  state  for  some  time,  there  follows  a  benumbing  sensa- 
tion in  the  head,  with  pains,  not  acute,  shooting  along  the  brow; 
the  head  feels  as  a  heavy  mass,  without  any  individuality  in  its 
operations.  Then  there  is  bleeding  at  the  nose  in  the  mornings 
when  newly  out  of  bed ;  after  that  comes  giddiness ;  objects  are 
seen  flitting  before  the  eyes,  and  momentary  feelings  as  of  the  earth 
lifting  up,  and  then  leaving  the  feet,  so  as  to-  cause  a  stagger.  .  This 
is  accompanied  with  feelings  of  terror,  gloomy  apprehension,  and 
irritability  of  temper.  Then  follows  a  rushing  of  blood  to  the 
head;  the  rush  is  felt  behind  the  ears  with  a  kind  of  hissing  noise, 
causing  severe  pain  and  blindness :  this  passes  off  in  a  few  seconds, 
leaving  a  giddiness  which  lasts  for  several  minutes.  In  our  own 
case  the  rushing  of  blood  was  without  pain,  but  attended  with  in- 
stant blindness,  and  then  followed  with  giddiness.  For  months 
afterwards  a  dimness  remained  as  if  a  mist  intervened  between  us 
and  the  objects  looked  at:  it  was  always  worse  towards  evening, 
when  we  grew  very  languid  and  inclined  to  sleep.  We  rose  com- 
paratively well  in  the  morning :  yet  were  restless,  our  stomach 
was  acid,  visage  pale,  features  sharp,  eyes  sunk  in  the  head,  and 
round  them  dark  in  color:  these  effects  were  slowly  developed. 
Our  experience  was  nearly  three  years. 

We  have  been  thus  particular  in  detailing  these  effects,  as  a 
warning  to  all  employed  in  the  process;  but  we  have  no  doubt  that 


COATING  WITH   VARIOUS   METALS.  617 

in  lofty  rooms,  airy  and  well  ventilated,  these  effects  would  not  be 
felt.  Employers  would  do  well  to  look  to  this  matter ;  and  ama- 
teurs, who  only  use  a  small  solution  in  a  tumbler,  should  not,  as 
the  custom  sometimes  is,  keep  it  in  their  bed- rooms;  the  practice  is 
decidedly  dangerous. 

PRACTICAL  SUGGESTIONS  IN  GILDING. — According  to  the  amount 
of  gold  deposited,  so  will  be  its  durability :  a  few  grains  will  serve 
to  give  a  gold  color  to  a  very  large  surface,  but  it  will  not  last:  this 
proves,  however,  that  the  process  may  be  used  for  the  most  inferior 
quality  of  gilding.  Gold  thinly  laid  upon  silver  will  be  of  a  light 
color,  because  of  the  property  of  gold  to  transmit  light.  The  so- 
lution for  gilding  silver  should  be  made  very  hot,  but  for  copper 
it  should  be  at  its  minimum  heat.  A  mere  blush  may  be  sufficient 
for  articles  not  subjected  to  wear ;  but  on  watch-cases,  pencil-cases, 
chains,  and  the  like,  a  good  coating  should  be  given.  An  ordi- 
nary sized  watch-case  should  have  from  20  grains  to  a  penny- 
weight ;  a  mere  coloring  will  be  sufficient  for  the  inside,  but  the 
outside  should  have  as  much  as  possible.  A  watch-case  thus  gilt, 
for  ordinary  wear,  will  last  five  or  six  years  without  becoming 
bare.  We  have  known  some  to  be  in  use  full  six  years  without 
losing  their  covering.  Small  silver  chains,  such  as  those  sold  at 
eight  shillings,  should  have  12  grains ;  pencil-cases,  of  ordinary 
size  should  have  from  3  to  5  grains ;  a  thimble  from  1  to  2  grains. 
These  suggestions  will  serve  as  a  guide  to  amateur  gilders,  many 
of  whom,  having  imparted  only  a  color  to  their  pencil-cases,  feel 
chagrin  and  disappointment  upon  seeing  them  speedily  become 
bare;  hence  arises  much  of  the  obloquy  thrown  upon  the  process. 


CHAPTEE  XXXII. 

RESULTS  OF  EXPERIMENTS   ON   THE  DEPOSITION   ON   OTHER  METALS 
AS  COATINGS. 

COATING  WITH  PLATINUM. — This  metal  has  never  yet  been  suc- 
cessfully deposited  as  a  protecting  coating  to  other  metals.  A  solu- 
tion may  be  made  by  dissolving  it  in  a  mixture  of  nitric  and  muri- 
atic acids,  the  same  as  is  employed  in  dissolving  gold ;  but  heat 
must  be  applied.  The  solution  is  then  evaporated  to  dryness,  and 
to  the  remaining  mass  is  added  a  solution  of  cyanide  of  potassium; 
next,  it  must  be  slightly  heated  for  a  short  time,  and  then  filtered. 
This  solution,  evaporated,  yields  beautiful  crystals  of.  cyanide  of 
platinum  and  potassium;  but  it  is  unnecessary  to  crystanize  the  salt. 
A  very  weak  battery  power  is  required  to  deposit  the  metal :  the 
solution  should  be  heated  to  100°.  Great  care  must  be  taken  to 
obtain  a  fine  metallic  deposit :  indeed  the  operator  may  not  sue- 


618  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

ceed  once  in  twenty  times  in  getting  more  than  a  mere  coloring  of 
metal  over  the  surface,  and  that  not  very  adhesive.  The  causes  of 
the  difficulty  are  probably  these :  the  platinum  used  as  an  electrode 
is  not  acted  upon;  the  quantity  of  salt  in  solution  is  very  little;  it 
requires  a  particular  battery  strength  to  gives  a  good  deposit,  and 
the  slightest  strength  beyond  this  gives  a  black  deposit ;  so  that, 
were  the  proper  relations  obtained,  whenever  there  is  any  deposit, 
the  relations  of  battery  and  solution  are  changed,  and  the  black 
pulverulent  deposit  follows. 

We  have  occasionally  succeeded  in  obtaining  a  bright  metallic 
deposit  of  platinum,  possessing  the  qualities  of  adhesion  and  dura- 
bility :  some  of  the  articles  thus  covered  presented  no  signs  of 
change  after  many  years :  but  we  have  never  been  so  fortunate  as 
to  get  a  platinum  deposit  that  could  protect  any  metal  from  the 
action  of  acids,  or  other  fluids  by  which  the  metal  could  be-  affected. 
We  have  covered  iron,  such  as  the  end  of  a  glass-blower's  blow- 
pipe, so  that  it  could  be  made  red-hot  without  the  iron  rusting,  but 
rather  taking  the  characteristic  appearance  of  platinum :  but  even 
that  did  not  protect  the  iron  from  rusting  when  it  was  put  a  short 
time  into  water,  or  kept  exposed  to  moist  air.  We  have  seen  again 
and  again  recommendations  of  certain  solutions  of  platinum  for  the 
purpose  of  obtaining  a  reguline  metal,  and  no  doubt  it  has  been 
obtained,  but,  as  stated  above,  we  believe  more  incidentally  than 
at  will.  The  protoxalate  of  platinum  has  been  strongly  recom- 
mended for  covering  copper  and  brass  with  platinum.* 

COATING  WITH  PALLADIUM. — Palladium  is  a  metal  very  easily 
deposited.  The  solution  is  prepared  by  dissolving  the  metal  in 
nitro- muriatic  acid,  and  evaporating  the  solution  nearly  to  dry- 
ness  ;  then  adding  cyanide  of  potassium  till  the  whole  is  dissolved : 
the  solution  is  then  filtered  and  ready  for  use.  The  cyanide  of 
potassium  holds  a  large  quantity  of  this  metal  in  solution,  and  the 
electrode  is  acted  upon  while  the  deposit  is  proceeding.  Articles 
covered  with  this  metal  assume  the  appearance  of  the  metal ;  but 
so  far  as  we  are  aware,  it  has  not  yet  been  applied  to  any  practical 
purpose.  It  requires  rather  a  thick  deposit  to  protect  metals  from 
the  action  of  acids,  which  is,  probably,  the  only  us.e  it  can  be 
applied  to. 

COATING  WITH  NICKEL. — Nickel  is  very  easily  deposited ;  and 
may  be  prepared  for  this  purpose  by  dissolving  it  in  nitric  acid, 
then  adding  cyanide  of  potassium  to  precipitate  the  metal ;  after 
which  the  precipitate  is  washed  and  dissolved  by  the  addition  of 
more  cyanide  of  potassium.  Or  the  nitrate  solution  may  be  pre- 
cipitated by  carbonate  of  potash ;  this  should  be  well  washed,  and 
then  dissolved  in  cyanide  of  potassium;  a  proportion  of  carbonate 
of  potash  will  be  in  the  solution,  which  we  have  not  found  to  be 
detrimental:  This  latter  method  of  preparing  the  nickel  plating 
solution  is  simple,  and,  therefore,  has  our  recommendation.  The 


*  Polytechni.  Constah.     1855. 


COATING   WITH   VARIOUS    METALS.  619 

metal  is  very  easily  deposited ;  it  yields  a  color  approaching  to 
silver,  which  is  not  liable  to  tarnish  on  exposure  to  the  air.  A 
coating  of  this  metal  would  be  very  useful  for  covering  common 
work  such  as  gasaliers,  and  other  gas-fittings,  and  even  common 
plate.  The  great  difficulty  experienced  is  to  obtain  a  positive 
electrode :  the  metal  is  very  difficult  to  fuse,  and  so  brittle  that  we 
have  never  been  able  to  obtain  either  a  plate  or  a  sheet  of  it. 
Could  this  difficulty  be  easily  overcome,  the  application  of  nickel 
to  the  coating  of  other  metals  would  be  extensive,  and  the  property 
of  not  being  liable  to  tarnish  would  make  it  eminently  useful  for 
all  general  purposes.  We  coated  articles  with  nickel  in  1845, 
which  were  exposed  to  the  air  for  many  years  without  tarnish, 
and  when  last  seen  by  the  author  exhibited  no  change. 

ANTIMONY,  ARSENIC,  TIN,  IRON,  LEAD,  BISMUTH.  AND  CADMIUM. 
— We  have  deposited  these  metals  from  their  solutions  in  cyanide 
of  potassium ;  but  not  for  any  useful  application. 

IRON. — Iron  may  be  very  easily  deposited  from  its  sulphate: 
dissolve  a  little  crystalline  sulphate  of  iron  in  water,  and  add  a  few 
drops  of  sulphuric  acid  to  the  solution :  one  pair  of  Smee's  battery 
may  be  used  to  deposit  the  iron  upon  copper  or  brass.  The  metal 
in  this  pure  state  has  a  very  bright  and  beautiful  silver  color. 

LEAD. — Lead  may  be  deposited  from  a  solution  of  an  acid  salt, 
such  as  the  acetate,  but  requires  some  management  or  strength  of 
battery:  it  may  also  be  deposited  from  its  solution  in  potash  or 
soda. 

ALUMINIUM  AND  SILICIUM. — Since  the  publication  of  the  former 
edition  of  this  work,  new  methods  have  been  discovered  for  obtain- 
ing the  base  or  metal  of  alumina  and  silica,  or  clay  and  sand,  in 
the  metallic  state  possessing  extraordinary  properties.  One  of  the 
methods  successfully  adopted,  is  by  fusing  in  a  small  crucible 
some  chloride  or  fluoride  of  aluminium,  and  when  in  fusion,  in- 
serting two  steel  poles  in  connection  with  a  battery  which  reduces 
the  salt,  giving  small  globules  of  the  metal  aluminium. 

Attempts  have  also*been  made  to  deposit  the  metals  from  their 
cyanous  solution  as  coating  upon  other  metals  in  the  usual  way. 
We- have  not  ourselves  tried  any  experiments  upon  these  metals, 
but  we  take  the  following  results  of  experiments  from  Mr.  G.  Gore 
of  Birmingham,  who  seems  to  have  given  the  subject  a  good  deal 
of  attention : 

"It  has  long  been  known  to  chemists  that  all  kinds  of  clay, 
stone,  and  sand,  of  which  Jhe  earth  is  composed,  consist  of  metals 
combined  with  oxygen,  carbonic  acid,  sulphuric  acid,  and  other 
non- metallic  elements,  forming  therewith  oxides,  carbonates,  sul- 
phates, etc.;  thus  clay  is  an  oxide  of  aluminium,  sand  an  oxide  of 
silicium,  limestone  a  carbonate  of  calcium ;  but  the  separation  of 
the  metallic  bases  from  the  non-metallic  elements  with  which  they  aro 
combined  has  been  a  matter  of  so  great  difficulty,  that  few  chemists 
have  put  themselves  to  the  trouble  of  accomplishing  it,  and  those 
who  have  done  so  have  made  use  of  the  most  powerful  means  and 


620  THE  PRACTICAL  METAL- WORKER'S   ASSISTANT. 

reducing  agents,  such  as  large  voltaic  batteries,  potassium,  etc., 
and  have  then  obtained  them  in  a  state  of  alloy  or  combination 
with  mercury.  Sir  Humphrey  Davy,  the  discoverer  of  most  of 
these  bases,  in  his  experiments  on  the  decomposition  of  the  alkalies 
and  earths,  used  a  powerful  battery,  consisting  of  500  pairs  of 
plates,  and  then  succeeded  in  obtaining  them  combined  with  mer- 
cury, from  which  they  were  afterwards  separated.  Wohler  and 
Berzelius,  in  their  discoveries  of  the  means  of  separating  the  metals 
aluminium  and  silicium  from  their  respective  compounds,  clay  and 
sand,  used  a  high  temperature  and  potassium,  and  then  succeeded 
in  obtaining  them  in  the  condition  of  dull  metallic  powders,  nearly 
infusible. 

"  By  a  means  recently  discovered,  and  described  in  the  March 
number  of  the  Philosophical  Magazine  for  this  year,  I  have  suc- 
ceeded in  depositing  the  metals  aluminium  from  clay,  and  silicium 
from  sandstone,  each  in  a  perfect  metallic  condition,  by  dissolving 
pipe  clay,  common  red  sand,  pounded  stone,  etc.,  in  various  chemical 
liquids,  and  passing  currents  of  electricity  from  ordinary  small 
voltaic  batteries  through  the  solutions. 

'•  My  attention  has  since  been  directed  to  produce  simple  pro- 
cesses, whereby  any  person  not  possessing  a  knowledge  of  chem- 
istry may  readily  coat  articles  with  those  metals,  and  thus  cause 
the  discovery  to  be  immediately  applied  -to  human  benefit  in  the 
arts  and  manufactures,  and  the  following  are  the  results  of  my  ex- 
periments : 

"  To  coat  articles  of  copper,  brass,  or  German  silver,  with  alumi- 
nium, take  equal  measures  of  sulphuric  acid  and  water,  or  take  one 
measure  each  of  sulphuric  and  hydrochloric  acids  and  two  mea- 
sures of  water ;  add  to  the  water  a  small  quantity  of  pipe-clay,  in 
the  proportion  of  5  or  10  grs.  by  weight  to  every  ounce  by  mea- 
sure of  water  (or  J  oz.  to  the  pint):  rub  the  clay  with  the  water 
until  the  two  are  perfectly  mixed,  then  add  the  acid  to  the  clay 
solution,  and  boil  the  mixture  in  a  covered  glass  vessel  one  hour. 
Allow  the  liquid  to  settle,  take  the  clear, 'supernatant  solution, 
while  hot,  and  immerse  in  it  an  earthen  porous  cell,  containing  a 
mixture  of  one  measure  of  sulphuric  acid  and  ten  measures  of 
water,  together  with  a  rod  or  plate  of  amalgamated  zinc ;  take  a 
small  Smee's  battery,  of  three  or  four  pairs  of  plates,  connected, 
together  intensity  fashion,  and  connect  its  positive  pole  by  a  wire, 
with  a  piece  of  zinc  in  the  porous  cell.  Having  perfectly  cleaned 
the  surface  of  the  article  to  be  coatedt  connect  it  by  a  wire  with 
the  negative  pole  of  the  battery,  and  immerse  it  in  the  hot  clay 
solution ;  immediately  abundance  of  gas  will  be  evolved  from  the 
whole  of  the  immersed  surface  of  the  article,  and  in  a  few  minutes, 
if  the  size  of  the  article  is  adapted  te  the  quantity  of  the  current 
of  electricity  passing  through  it,  a  fine  white  deposit  of  aluminium 
will  appear  all  over  the  surface.  It  may  then  be  taken  out,  washed 
quickly  in  clean  water,  and  wiped  dry,  and  polished ;  but  if  a 
thicker  coating  is  required,  it  must  be  taken  out  when  the  deposit 


COATIXG   WITH   VARIOUS   METALS.  621 

becomes  dull  in  appearance,  washed,  dried,  polished,  and  re-im- 
mersed ;  and  this  must  be  repeated  at  intervals,  as  often  as  it  be- 
comes dull,  until  the  required  thickness  is  obtained.  With  small 
articles  it  is  not  absolutely  necessary,  either  in  this  or  the  follow- 
ing process,  that  a  separate  battery  be  employed,  as  the  article  to 
be  coated  may  be  connected  by  a  wire  with  a  piece  of  zinc  in  the 
porous  cell,  and  immersed  in  the  outer  liquid,  when  it  will  receive 
a  deposit,  but  more  slowly  than  when  a  battery  is  employed. 

"  To  coat  articles  with  silicium,  take  the  following  proportions : 
three-quarters  of  an  ounce,  by  measure,  of  hydrofluoric  acid,  \  oz. 
of  hydrochloric  acid,  and  40  or  50  grs.  either  of  precipitated  silica, 
or  of  fine  white  sand  (the  former  dissolves  most  freely),  and  boil  the 
whole  together  for  a  few  minutes,  until  no  more  silica  is  dissolved. 
Use  this  solution  exactly  in  the  same  manner  as  the  clay  solution, 
and  a  fine  white  deposit  of  metallic  silicium  will  be  obtained,  pro- 
vided that  the  size  of  the  article  is  adapted  to  the  quantity  of  the 
electric  current :  common  red  sand,  or  indeed  any  kind  of  silicious 
stone,  finely  powdered,  may  be  used  in  place  of  the  white  sand,  and 
with  equal  success,  if  it  be  previously  boiled  in  hydrochloric  acid, 
to  remove  the  red  oxide  of  iron  or  other  impurities. 

"Both  in  depositing  aluminium  and  silicium,  it  is  necessary  to 
well  saturate  the  acid  with  the  solid  ingredients  by  boiling,  other- 
wise very  little  deposit  of  metal  will  be  obtained. 

"  Among  the  many  experiments  I  have  made  upon  this  subject, 
the  following  area  few  of  the  most  interesting: — 

"Experiment  1. — Boiled  some  pipe-clay  in  caustic  potash  and 
water,  poured  the  clear  part  of  the  solution  into  a  glass  vessel,  and 
immersed  in  it  a  small  earthen  porous  cell,  containing  dilute  sulphuric 
acid  and  a  piece  of  amalgamated  zinc ;  immersed  a  similar  piece  of 
bright  sheet  copper  in  the  alkaline  liquid,  and  connected  it  with 
the  negative  pole  of  a  small  Smee's  battery  of  three  pairs  of  plates, 
connected  the  zinc  plate  with  the  positive  pole,  and  let  the  whole 
stand  undisturbed  all  night ;  on  examining  it  next  morning  I  found 
the  piece  of  copper  coated  with  a  white  silver-like  deposit  of  met- 
allic aluminium. 

"Experiment  2. — Obtained  from  a  railway  cutting  in  the  town 
a  small  piece  of  the  sand  rock  upon  which  Birmingham  is  built, 
boiled  it  in  hydrochloric  acid,  to  remove  the  red  oxide  of  iron, 
washed  it  clean  with  water,  and  dissolving  it  by  boiling  it  in  a  mix- 
ture of  hydrofluoric  acid,  nitric  acid,  and  water ;  immersed  in  this 
solution,  a  porous  cell  with  dilute  acid  and  zinc,  as  before ;  con- 
nected a  piece  of  brass  with  the  zinc  by  a  wire,  and  suspended  it 
in  the  outer  liquid,  which  was  kept  hot  bv  a  small  spirit  lamp  be- 
neath ;  after  allowing  the  action  to  proceed  several 'hours,  I  found 
the  piece  of  brass  beautifully  coated  with  white  metallic  silicium. 

"  Experiment  3. — Took  one  part,  by  weight,  of  the  same  sand- 
stone, after  being  purified  by  the  hydrochloric  acid,  and  2£  parts  of 
carbonate  of  potash,  fused  them  together  in  a  crucible  until  all 
evolution  of  gas  ceased,  and  a  perfect  glass  was  formed ;  poured 


622  THE   PRACTICAL   METAL- WORKER'S   ASSISTANT. 

out  the  melted  glass,  and  when  cold,  dissolved  it  in  water,  and  used 
this  solution  in  the  same  manner  as  the  former  ones,  allowing  the 
action  to  proceed  about  12  hours,  when  a  good  white  deposit  of 
metallic  silicium  was  obtained. 

"Experiment  4. — Took  some  stones  with  which  the  streets  of 
Birmingham  are  macadamised,  pounded  them  fine  in  a  mortar,  boiled 
the  powder  in  hydrochloric  acid,  to  purify  it  from  iron,  washed  it 
well  in  water,  and  dissolved  it  by  boiling  an  excess  of  it  in  a  mix- 
ture of  f  oz.,  by  measure,  of  hydrofluoric  acid,  |  oz.  of  water,  and 
^  oz.  each  of  nitric  and  hydrochloric  acids,  until  no  more  would 
dissolve;  used  the  clear  portion  of  this  solution  in  the  same  man- 
ner as  the  former  liquids,  and  readily  coated  in  it  a  piece  of  brass 
with  a  beautifully  white  deposit  either  of  aluminium  or  silicium. 
From  these,  and  many  other  experiments  which  I  have  tried,  it  is 
quite  clear  that  common  metal  articles  may  be  readily  coated  with 
white  metals,  possessing  similar  characters  to  silver,  from  solutions 
of  the  most  common  and  abundant  materials,  and  thus  bring  within 
the  purchase  of  the  poorer  classes  articles  of  taste  and  cleanliness 
which  are  at  present  only  to  be  obtained  by  the  comparatively, 
wealthy." 

Tm. — Tin  is  easily  deposited  from  a  solution  of  protochloride 
of  tin.  If  the  two  poles  or  electrodes  be  kept  about  two  inches 
apart,  a  most  beautiful  phenomenon  may  be  observed.  The  de- 
composition of  the  solution  is  so  rapid  that  it  shoots  out  from  the 
negative  electrode  like  tentacula,  or  feelers,  towards  the  positive, 
which  it  reaches  in  a  few  seconds.  The  space  between  the  poles 
seems  like  a  mass  of  crystallized  threads,  and  the  electric  current 
passes  through  them  without  effecting  further  decomposition.  So 
tender  are  these  metallic  threads  that  when  lifted  out  of  the  solu- 
tion they  fall  upon  the  plate  like  cobweb.  Seen  through  a  glass 
they  exhibit  a  beautiful  crystalline  structure.  If  a  circular  elec- 
trode of  tin  is  used,  and  a  small  wire  put  in  the  centre  of  the 
chloride  solution,  the  thread-like  crystals  will  shoot  out  all  round, 
and  give  quite  a  metallic  conferva.  Tin  may  also  be  deposited 
from  its  solution  in  caustic  potash  or  soda. 

ANTIMONY. — In  the  deposition  of  antimony  Mr.  Gore  has  ob- 
served a  curious  and  interesting  phenomenon,  that  the  metal  during 
its  deposition,  and  after  some  has  been  deposited,  explodes  occa- 
sionally, the  particles  being  thrown  about  by  the  shock. 

DEPOSITION  OF  ALLOYS.— Many  attempts  have  been  made  to 
deposit  alloys  of  metals  from  their  solutions.  That  two  or  more 
metals  can  be  deposited  from  a  solution  we  have  seen  sufficient 
evidence ;  but  the  means  to  regulate  the  proportions  of  each,  and 
to  make  such  a  process  practical,  have  yet  to  be  discovered.  It  is 
hardly  possible  to  get  a  mixed  solution  of  any  two  metals  that  are 
exactly  equally  decomposable ;  or,  in  other  words,  that  the  metals 
under  the  circumstances  in  which  they  are  placed  are  exactly  of 
equal  conducting  power.  Hence  the  electric  current  will  always 
travel  through  the  one  that  offers  the  least  resistance,  and  there 


COATING   WITH   VARIOUS   METALS.  623 

will  be  none  of  the  other  metallic  solution  decomposed,  or  metal 
deposited,  until  the  quantity  of  electricity  js  greater  than  the  best 
conducting  metal  in  the  solution  will  allow  to  pass ;  then  the  other 
metal  will  be  deposited  in  proportion  to  the  extra  electrical  power 
that  passes.  As,  for  example,  take  a  mixture  of  cyanide  of  gold, 
silver,  and  copper,  in  cyanide  of  potassium.  The  silver  in  this 
state  is  so  much  superior  in  its  conducting  power  to  the  other  salts, 
that  all  the  silver  may  be  deposited  from  the  solution  by  a  weak 
battery  without  any  of  the  other  metals.  If  the  solution  be  after- 
wards heated,  and  the  battery  power  kept  so  that  no  gas  is  allowed 
to  escape  from  the  articles,  the  gold  may  be  deposited  without  any 
copper ;  but  if  the  gas  is  allowed  to  flow  from  the  article  receiving 
the  deposit,  the  copper  will  be  deposited,  and  often  more  abun- 
dantly than  the  gold,  as  the  escape  of  gas  is  not  consistent  with  a 
reguline  deposit  of  gold.  We  have  thus  deposited  an  alloy  of 
gold  and  copper  ;  we  have  also  deposited  gold  and  silver,  but  the 
alloy  was  very  inferior  and  irregular.  Alloys  can  be  obtained 
from  silver  and  palladium,  from  cyanide  solutions,  from  zinc  and 
copper,  from  a  solution  of  their  sulphates ;  but  in  no  instance  have 
we  found  good  alloys,  or  alloys  that  could  pass  as  such  in  name  or 
appearance.  We  have  seen  articles,  such  as  iron;  covered  with 
copper  and  zinc  in  this  manner,  or  in  alternate  layers,  and  the 
articles  having  the  coating  heated  in  charcoal,  by  which  means  a 
brass  of  fair  appearance  was  obtained,  but  the  process  is  attended 
with  practical  difficulty,  and  the  product  cannot  be  called  deposited 
brass. 

Several  patents  have  been  taken  out  for  the  deposition  of 
alloys  of  various  sorts.  The  following,  by  Morris  and  Johnson, 
embraces  a  wide  range,  and  being  well  described  we  will  copy  the 
specification : 

"  This  invention  consists  in  the  employment  of  solutions  com- 
posed of  cyanide  of  potassium  and  carbonate  of  ammonia,  to 
which  are  added  cyanides,  carbonates,  and  other  compounds  of 
metals,  in  proportions  according  to  the  amount  of  deposit  required 
to  be  made. 

"  In  order  that  the  invention  may  be  fully  understood  and  car- 
ried into  effect,  the  patentees  proceed  to  describe  the  means  pursued 
by  them  as  follows :  These  improvements  consist  in  the  employ- 
ment of  solutions  composed  of  carbonate  of  ammouia  (the  carbon- 
ate of  ammonia  of  commerce,  or  the  sesqui-carbonate  of  ammonia 
of  chemists),  and  cyanide  of  potassium,  to  which  are  added  car- 
bonates, cyanides,  or  other  compounds  of  metals,  in  various  pro- 
portions. For  the  well-known  alloy,  brass,  carbonate  of  ammonia 
and  cyanide  of  potassium  are  used  in  the  following  proportions, 
namely — To  each  or  every  gallon  of  water  are  added  1  Ib.  of 
carbonate  of  ammonia,  1  Ib.  of  cyanide  of  potassium,  2  ozs.  of 
cyanide  of  copper,  and  1  oz.  of  cyanide  of  zinc.  These  propor- 
tions may  be  varied  to  a  considerable  extent.  Or  the  patentees 
take  the  before-named  solution  of  carbonate  of  ammonia  and 


V 


624  THE  PRACTICAL   METAL-WOBKER's  ASSISTANT. 

cyanide  of  potassium,  in  the  proportion  of  1  Ib.  of  each  to  one 
gallon  of  water ;  and  they  take  a  large  sheet  of  brass  of  the  de- 
sired quality,  and  make  it  the  anode  or  positive  electrode,  in  the 
aforesaid  solution,  of  a  powerful  galvanic  battery  or  magneto- 
electric  machine,  and  a  small  piece  of  metal,  and  make  it  the 
cathode  or  negative  electrode,  from  which  hydrogen  must  be 
freely  evolved.  This  operation  is  continued  till  the  solution  has 
taken  up  a  sufficient  quantity  of  the  brass  to  produce  a  reguline 
deposit.  The  solution  may  be  used  cold ;  but  it  is  desirable,  in 
many  cases,  to  heat  it  (according  to  the  nature  of  the  article  or 
articles  to  be  deposited  upon)  up  to  212°  Fahr.  For  wrought  or 
fancy  work  about  150°  Fahr.  will  give  excellent  results.  The 
galvanic  battery,  or  magneto-electric  machine,  must  be  capable  of 
evolving  hydrogen  freely  from  the  cathode  or  negative  electrode, 
or  article  attached  thereto.  It  is  preferred  to  have  a  large  anode  or 
positive  electrode,  as  this  favors  the  evolution  of  hydrogen.  The 
article  or  articles  treated  as  before  described  will  immediately  be- 
come coated  with  brass.  By  continuing  the  process  any  desired 
thickness  may  be  obtained.  Should  the  copper  have  a  tendency  to 
come  down  in  a  greater  proportion  than  is  desired,  which  may  be 
known  by  the  deposit  assuming  too  red  an  appearance,  it  is  cor- 
rected by  the  addition  of  carbonate  of  ammonia,  or  by  a  reduction 
of  temperature,  when  the  solution  is  heated.  Should  the  zinc  have 
a  tendency  to  come  down  in  too  great  a  proportion,  which  may  be 
seen  by  the  deposit  being  too  pale  in  its  appearance,  this  is  cor- 
rected by  the  addition  of  cyanide  of  potassium  or  by  an  increase 
of  temperature. 

"  The  alloy,  German  silver,  is  deposited  by  means  of  a  solution 
consisting  of  carbonate  of  ammonia  and  cyanide  of  potassium  (in 
the  proportions  previously  given  for  the  brass),  and  cyanides  or 
other  compounds  of  nickel,  copper,  and  zinc,  in  the  requisite  pro- 
portions to  constitute  German  silver.  It  is  however  preferred  to 
make  the  solution  by  nieans  of  the  galvanic  battery  or  magneto- 
electric  machine,  as  above  described  for  brass.  Should  the  copper 
of  the  German  silver  come  down  in  too  great  a  proportion,  this  is 
corrected  by  adding  carbonate  of  ammonia,  which  brings  down  the 
zinc  more  freely  ;  and  should  it  be  necessary  to  bring  down  the 
copper  in  greater  quantity,  cyanide  of  potassium  is  added — such 
treatment  being  similar  to  that  of  the  brass  before  described. 

"  The  solutions  for  the  alloys  of  gold,  silver,  and  other  alloys  of  - 
metals,  are  made  in  the  same  manner  as  above  stated,  by  employ- 
ing anodes  of  the  alloy  or  alloys  to  be  deposited  ;  or  by  adding  to 
the  solutions  the  carbonates,  cyanides  or  other  compounds,  in  the 
proportions  forming  the  various  alloys — always  using  in  depositing 
un  anode  of  the  required  alloy.  These  solutions  are  subject  to  the 
same  treatment  and  control  as  those  of  the  brass  and  German  silver 
before  described. 

"  The  patentees  claim  the  combination  of  the  carbonate  of  am- 
monia, before  named  or  other  carbonates  of  ammonia  and  cyanide 


COATING   WITH    VARIOUS   METALS.  625 

of  potassium,  as  the  ingredients  for  their  solutions  for  depositing 
alloys  of  metals." 

The  expense  of  depositing  common  metals  will  remain  a  barrier 
to  the  use  of  electro-metallurgy  in  making  such  alloys  as  brass,  a 
consideration  which  some  patentees  do  not  seem  to  consider.  "We 
have  the  following  given  as  methods  for  mixing  up  solutions  for 
depositing  brass,  which  will  prove  our  position  : 

"As  an  illustration  of  this  invention  we  take  the  patentee's 
method  of  depositing  a  coating  of  brass  by  galvanic  agency,  in 
which  he  employs  the  following : — 1.  A  solution  of  the  double 
chloride  of  zinc  and  ammonia. — 2.  A  solution  of  the  double  chlo- 
ride of  zinc  and  potassium. — 8.  A  solution  of  the  double  chloride 
of  zinc  and  sodium. — 4.  A  solution  of  the  double  acetate  of  zino 
and  ammonia. — 5.  A  solution  of  the  double  acetate  of  zinc  and 
potassium. — 6.  A  solution  of  the  acetate  of  zinc  and  soda. — 7.  A 
saturated  solution  of  carbonate  of  zinc,  and  carbonate  of  ammonia. 
— 8.  A  solution  of  the  double  tartrate  of  zinc,  and  of  potash,  soda, 
or  ammonia.  (To  one  thousand  parts  of  the  solution  of  tartrate 
of  zinc,  indicating  three  degrees  on  the  salinometer,  thirty  parts  of 
hydrochlorate  of  ammonia,  and  eighty  parts  of  hydrochloric  acid 
must  be  added.) — 9.  A  solution  of  citrate  of  zinc  rendered  soluble 
by  an  excess  of  citric  acid. — 10.  A  solution  of  tartrate  of  zinc  in 
potash  or  soda.  With  each  of  the  above  solutions  an  analogous 
solution  of  copper  must  be  mixed  in  the  proportion  suitable  for 
obtaining  the  required  depth  of  color." 

Besides  the  ordinary  electro-metallurgical  operations,  the  public 
are  from  time  to  time  told  through  the  press  that  the  process  has 
been  applied  to  the  extraction  of  metals  from  their  ores,  but  on 
examination  the  statement  is  invariably  found  to  be  incorrect,  the 
metal  being  in  all  cases  separated  from  the  ore  by  means  of  an  acid 
or  acids,  and  the  electro-metallurgical  operations  not  applied  till 
after  this  separation  takes  place ;  so  that  its  application  is  altogether 
apart  from  the  extraction  of  the  metal  from  the  ore.  Such  an  ap- 
plication for  common  metals  is  commercially  absurd ;  and  nothing 
can  exhibit  the  want  of  practical  application  so  much  as  some  of 
the  patents  taken  out  for  this  object.  The  greater  number  of  these 
patents  are  intended  for  copper  ores,  upon  which  we  will  offer  a 
lew  remarks.  It  will  be  seen  from  the  principles  of  deposition, 
that,  allowing  the  copper  was  all  in  solution  to  be  deposited  by  a 
battery,  the  cheapest  form  known  will  give  the  loss  of  one  ton  of 
zinc  and  sulphuric  acid  to  get  one  ton  of  copper,  which  would  be- 
upwards  of  £20  for  Jhe  materials  destroyed,  while  a  ton  of  coppi-i- 
may  be  smelted  by  the  ordinary  process  for  half  that  sum.  \W 
give  the  following  extract  of  a  patent  as  an  illustration,  not  lx$- 
cause  it  is  worse  than  others,  but  being  more  definite  in  its  methods, 
and  battery  than  most  of  these  patents,  and  the  patentee  an  excel- 
lent electrician. 

"Mr.  Andrew  Crosse,  of  Broomfield.  the  electrician,  has  just 
specified  his  patent  for  improvements  in  the  extraction  of  metala 
40 


626  THE   PRACTICAL   METAL- WORKER'S   ASSISTANT. 

from  their  ores.  The  apparatus  employed  for  this  purpose  con- 
sists of  a  wooden  or  earthenware  vessel  capable  of  holding  from 
250  to  300  quarts,  at  a  short  distance  above  the  bottom  of  which 
is  a  movable  platinum  frame  covered  with  a  netting  of  platinum 
wire,  the  meshes  being  about  1  inch  each  way.  This  frame  is  con- 
nected to  the  positive  pole  of  a  Daniell's  battery  by  a  platinum 
wire,  covered  with  a  non-conducting  material  throughout  those 
parts  of  it  exposed  to  the  liquid  in  the  vessel ;  the  negative  pole 
of  the  battery  being  connected  to  a  copper  wire,  from  which  is 
suspended  by  three  smaller  wires,  in  the  interior  of  the  vessel,  a 
bowl  of  wood  lined  with  sheet  copper  and  covered  with  a  cop- 
per wire  netting.  The  battery  in  connection  with  the  appara- 
tus should  consist  of  20  pairs  of  plates,  each  in  a  gallon  glass 
vessel,  filled  with  a  saturated  solution  of  sulphate  of  copper, 
to  which  has  been  added  from  l-20th  to  1-1  Oth  part  of  sulphuric 
acid. 

The  mode  of  operating  is  as  follows-:  The  vessel  is  partially 
filled  with  water  acidulated  with  sulphuric  acid — 230  quarts  of 
water  and  5  quarts  of  sulphuric  acid  being  a  convenient  quantity. 
About  15  Ibs.  of  the  copper  ore,  previously  calcined  and  reduced 
to  powder,  is  then  stirred  into  the  liquid  in  the  vessel  and  allowed 
to  subside,  after  which  the  platinum  frame  is  lowered  on  to  the 
surface  of  the  ore,  and  the  copper-lined  bowl  suspended  in  its 
place,  when  the  electric  current  immediately  begins  to  act ;  but  it 
is  preferred  to  allow  the  ore  to  remain  four  or  five  days  in  the 
acidulated  water  before  applying  the  electric  current.  The  liquid 
during  the  process  should  be  kept  heated  even  as  high  as  the  boil- 
ing point,  by  which  the  separation  of  the  copper  and  its  deposition 
in  the  bowl  will  be  facilitated.  The  time  occupied  in  effecting  this 
ie  generally  three  or  four  days,  when  the  whole  of  the  copper  is 
removed.  The  acid  liquid  and  sediment,  which  will  contain  any 
other  metals  that  may  have  been  present,  are  run  out  through  a 
plug-hole  in  the  bottom  of  the  vessel.  The  sediment  should  be 
tested  to  ascertain  if  it  still  contains  any  proportion  of  copper ; 
and  if  so,  it  can  be  mixed  with  fresh  calcined  ore  and  again  oper- 
ated on.  The  liquid  does  not  require  any  fresh  quantity  of  acid 
to  be  added  to  it  during  the  process,  and  afterwards  it  may  again 
be  similarly  used. 

Here  we  have  20  pairs  of  plates  recommended  to  be  used  in  the 
battery,  making  a  destruction  of  20  tons  of  zinc  and  acid  for  one 
ton  of  copper,  and  taking  four  days  to  deposit.  Twenty-one  tons  of 
copper  per  week  would  be  but  a  small  quantity  of  copper  made, 
compared  with  smelting ;  and  at  the  ordinary  per  centage  of  ore 
to  get  this,  there  will  have  to  be  operated  upon  300  tons  of  ore, 
requiring  acres  of  tanks,  heated  according  to  specification,  inde- 
pendent of  the  furnace  for  calcining.  Having  got  the  ore  calcined 
and  free  of  sulphur,  it  would  be  preferable  to  fuse  it  with  car- 
bonaceous matters  and  get  the  copper  direct.  Notwithstanding 
the  commercial  absurdity  of  all  these  applications  and  patents,  still 


COATING   WITH   VARIOUS   METALS.  627 

there  are  several  ingenious  adaptations  worthy  of  the  attention  of 
the  electro-metallurgist  as  a  study  in  his  profession. 

DEPOSITION  OF  BRONZE. — The  following  solutions  of  different 
metals  are  given  by  Brunei,  Bisson,  and  Gaugain,  as  being  capable 
of  giving  a  deposit  of  bronze : 

50  parts  Carbonate  of  Potash. 

2     "      Chloride  of  Copper 

4     "      Sulphate  of  Zinc. 
25     "      Nitrate  of  Ammonia. 

A  bronze  plate  is  used  as  the  positive  electrode.  The  deposit 
given  by  this  solution  has  been  seen  by  Becquerel,  who  mentions 
that  it  bears  comparison  with  any  ordinary  bronze  ill  appearance.* 
A  solution  of  the  above  materials  in  water  strikes  the  ear  as  some- 
what hypothetical :  that  a  mixed  solution  of  copper  and  zinc  will 
give,  under  certain  conditions,  a  compound  deposit  we  know,  and 
also  that,  with  a  quantity  of  other  salts  present,  will  give  peculiar 
tints  of  color,  a  circumstance  which  may  be  obtained  without  a 
compound  deposit.  But  the  difficulty  to  be  overcome  is  to  pro- 
portion the  deposit  of  different  metals,  so  that  we  may  make  up  a 
solution  and  battery  that  will  deposit  either  Mantz's  yellow  metal, 
Stirling's  yellow  metal,  gun  metal,  or  common  brass,  at  pleasure ; 
and  that  we  may  be  able  to  produce  compounds  that  are  constant 
and  unvarying :  so  that,  for  example,  we  could  deposit  silver  or 
gold  of  the  standard  quality,  all  which,  notwithstanding  the  many 
statements  that  have  been  made  in  print,  have  yet  to  be  discovered. 

We  have  thus  given  a  brief  review  of  the  practical  operations 
of  Electro- Metallurgy  for  the  guidance  of  the  student,  who  as  he 
proceeds,  will  find  that  the  difficulties  whieh  at  first  beset  his  path 
will  gradually  disappear:  easier  modifications  of  processes  will 
suggest  themselves,  as  all  operators  cannot  with  equal  facility  fol- 
low the  same  directions.  New  facts  will  reveal  themselves  to  his 
inquiries;  a  wide  field  of  interesting  and  profitable  research  will 
open  up  before  his  mind;  and  the  steady  and  persevering  experi- 
menter and  observer  will  not  fail  to  reap  an  abundant  harvest  of 
honor  and  gratification,  in  being  an  instrument  in  )romoting  the 
knowledge  of  the  working  of  the  laws  of  Nature. 


*  Progress  of  General  Science,  vol.  ii. 


fi28  THE   PRACTICAL   METAL- WORKER'S  ASSISTANT. 

CHAPTER  XXXIII. 

THEORETICAL   OBSERVATIONS. 

WE  have  described  at  considerable  length  the  practical  details 
connected  with  the  art  of  electro-metallurgy,  without  pausing  to 
inquire  into  the  philosophy  of  the  action  of  the  electric  currents 
by  which  the  effects  are  produced.  It  will  be  unnecessary  to  enter 
into  a  long  discussion  of  the  numerous  theories  that  have  been 
advanced  from  time  to  time  to  explain  the  action  that  takes  place 
in  a  battery  or  decomposing  cell,  while  the  current  is  passing 
through  the  solution — a  brief  reference  to  the  more  commonly 
received  opinions  being  sufficient  for  the  present  puruose. 

ACTION  OP  SULPHATE  OF  COPPER  ON  IRON. — In^  order  to  con- 
vey our  ideas  accurately,  let  us  suppose  that  the  solution  undergo- 
ing decomposition  is  sulphate  of  copper.  This  salt  is  composed  of 
sulphuric  acid  and  copper,  which  may  be  represented  as  SO4-fCu: 
these  are  held  together  according  to  the  law  of  chemical  affinity ; 
but  if  iron  is  put  into  the  solution,  the  combination  of  the  acid  and 
copper  will  be  dissolved  by  the  attraction  of  the  acid  to  the  iron, 
for  which  it  has  a  stronger  affinity  than  for  the  copper.  Hence 
iron,  put  into  sulphate  of  copper,  decomposes  it  thus : 

Cu,  SO  +  Fe  =  Fe,  SO4  +  Cu. 

"Were  we  to  put  a  piece  of  copper  into  a  solution  of  sulphate  of 
copper,  there  would  be  no  action,  the  forces  being  equal ;  but  if 
by  any  means  we  were  to  communicate  to  this  piece  of  copper  a 
higher  attractive  force  for  the  SO*  than  that  of  the  copper  which  is 
already  in  union  with  it,  we  should  cause  the  acid  to  leave  the 
copper  it  was  originally  combined  with,  and  to  combine  with  the 
new  piece  of  copper.  Bearing  these  general  principles  in  view,  we 
shall  proceed  to  state  the  different  opinions  of  authors  on  this 
subject. 

FARADAY'S  THEORY  OF  ELECTROLYSIS.  —  Professor  Faraday 
says — "  Passing  to  the  consideration  of  electro-chemical  decompo- 
sition, it  appears  to  me  that  the  effect  is  produced  by  an  internal 
corpuscular  action,  excited  according  to  the  direction  of  the  electric 
current,  and  that  it  is  due  to  a  force  either  superadded  to,  or  giving 
direction  to,  the  ordinary  chemical  affinity  of  the  bodies  present. 
The  body  under  decomposition  (say  sulphate  of  copper),  may  be 
considered  as  a  mass  of  acting  particles,  all  those  which  are  included 
in  the  course  of  the  electric  current  contributing  to  the  final  effect; 
and  it  is  because  the  ordinary  chemical  affinity  is  relieved,  weak- 
ened, or  partly  neutralized  by  the  influence  of  the  electric  current 
in  one  direction  parallel  to  the  course  of  the  latter,  and  strength- 
ened or  added  to  in  the  opposite  direction,  that  the  combining  par- 
ticles have  a  tendency  to  pass  in  opposite  courses. 

"  In  this  view  the  effect  is  considered  as  essentially  dependent  upon 


THEORETICAL   OBSERVATIONS.  629 

the  mutual  chemical  affinity  of  the  particles  of   opposite   kinds. 
Particles  aa  could  not  be  transferred  or  travel  from  one  pole  N, 
towards  the  other  pole  P,  unless  they 
found  particles  of  the  opposite  kind, 

bb,  ready  to  pass  in  the  contrary  direc-  /^~\a        tat  s~~\ 
tion ;  for  it  is  by  virtue  of  their  in-  \^_JP       ®        °       ® (*J 
creased  affinity  for  those  particles,  com- 
bined with  their  diminished  affinity  for  such  as  are  behind  them 
in  their  course,  that  they  are  urged  forward. 

"  I  conceive  the  effects  to  arise  from  forces  which  are  internal, 
relative  to  the  matter  under  decomposition,  and  not  external,  as 
they  might  be  considered,  if  directly  dependent  upon  the  poles.  I 
suppose  that  the  effects  are  due  to  a  modification  by  the  electric 
current  of  the  chemical  affinity  of  the  partifl.es,  through  or  by 
which  that  current  is  passing,  giving  them  the  power  of  acting 
more  forcibly  in  one  direction  than  in  another,  and  consequently 
making  them  travel  by  a  series  of  successive  decompositions,  in 
opposite  directions,  and  finally  causing  their  expulsion  or  exclu- 
sion at  the  boundaries  of  the  body  under  decomposition,  in  the 
direction  of  the  current,  and  that  in  larger  or  smaller  quantities, 
according  as  the  current  is  more  or  less  powerful."* 

In  the  above  figure,  the  particles  aa  may  be  termed  copper  Cu, 
and  the  particles  bb,  sulphuric  acid  SO*,  which  will  enable  us  to 
follow  the  comparison  of  the  different  views. 

GRAHAM'S  THEORY  OF  ELECTROLYSIS. — Professor  Graham  sup- 
poses that  the  compound  particles,  such  as  sulphate  of  copper, 
possess  polarity,  so  that  the  particles  in  the  bat- 
tery or  decomposition  cell  will  stand  in  rela-  Fie-  59°- 
tion  to  each  other  in  a  polar  chain,  as  in  Fig. 
590. 

He  then  represents  electrotyping  by  the 
porous  cell  system,  as  follows : 

"  The  liquids  on  either  side  of  the  porous  division  may  also  be 
different,  provided  they  have  both  a  polar  molecule.  Thus,  in 
Fig.  591  the  polar  chain  is  composed  of  molecules  of  hydrochloric 
acid,  extending  from  the  zinc  to  the  porous  division  at  a,  and  of 
molecules  of  chloride  of  copper  from  a,  to  the  copper  plate.  When 
the  Cl  of  molecule  1  unites  with  zinc,  the  II  of  that  molecule 
unites  with  the  Cl  of  molecule  2  (as  indicated  by  the  connecting 
bracket  below) ;  the  II  of  molecule  2  with  the  Cl  of  molecule  3  ; 
the  Cu  of  molecule  3  with  the  Cl  of  molecule  4 ;  and  the  Cu  of 
this  molecule  being  the  last  in  the  chain,  is  deposited  upon  the 
copper  plate.  Dilute  sulphuric  acid  in  contact  with  an  amalga- 
mated zinc  plate,  and  the  same  acid  fluid  saturated  with  sulphate 


of  copper  in  contact  with  the  copper  plate,  are  a  combination  of 
application."!     According  to  this  theory 


fluids  of  most  frequent 


Faraday's  Experimental  Researches,  vol.  i.  paragraphs  518,  519,  524. 
Graham's  Elements  of  Chemistry,  2d  edition,  1859. 


630  THE   PRACTICAL   METAL-WORKER'S  ASSISTANT. 

all  the  particles  between  the  zinc  and  copper  during  the  action  of 
the  batteries  will  be  performing  a  whirling  motion ;  for,  when  the 
Cl  of  molecule  1  is  liberated,  the  H  of  1  will  combine  the  Cl  of  2, 
which  compound  molecule  must  whirl  round  to  be  in  its  proper 
polar  position,  which  will  necessitate  that  interchange  distinctly 
referred  to  by  Professor  Faraday — a  mutual  transfer  of  the  ele- 
ments ;  the  Cl  will  pass  towards  the  zinc  plate,  and  the  H  and  Cu 
towards  the  copper  plate. 

Fig.  591. 


Zinc.  WZVT\       ^Y^\      ^^        /£VT>J  Copper. 


DANIELL'S  AND  MILLER'S  VIEWS. — Theories  varying  little  from 
these  were  held  by  the  late  Professor  Daniell,  till,  by  a  series  of 
interesting  experiments,  in  company  with  Professor  Miller,  he 
found  that  there  is  no  mutual  transfer  of  the  elements ;  that  the 
negative  element,  or  that  represented  above  as  Cl  or  SO4,  is  trans- 
ferred from  the  copper  to  the  zinc,  or  in  a  decomposition  cell  from 
the  negative  electrode  to  the  positive  electrode :  but  the  positive 
element — that  represented  by  H  or  Cu — is  not  transferred ;  there- 
fore, the  theories  of  Professors  Faraday  and  Graham  are  opposed 
to  a  fundamental  truth  experimentally  proved.  Professors  Daniell 
and  Miller  conclude  their  paper,  read  before  the  Eoyal  Society,  by 
the  following  observations : 

"  These  facts  are,  we  believe,  irreconcilable  with  any  of  the  mole- 
cular hypotheses  which  have  been  hitherto  imagined  to  account  for 
the  phenomena  of  electrolysis,  nor  have  we  any  more  satisfactory 
at  present  to  substitute  for  them  ;  we  shall  therefore  prefer  leaving 
them  to  the  elucidation  of  further  investigations  to  adding  one 
more  to  the  already  too  numerous  list  of  hasty  generalizations."* 

In  this  paper,  the  authors  state  that  they  found  certain  positive 
elements  transferred  in  small  proportions ;  thus,  potassium  from 
sulphate  of  potash  in  £  of  an  equivalent ;  barium,  from  nitrate  of 
barytes,  £  equivalent;  and  magnesia,  from  sulphate  of  magnesia, 
TV  equivalent.  This  was  a  difficulty  for  forming  any  theory,  but 
we  have  shown  that  this  difficulty  does  not  exist. 

In  all  cases  where  two  liquids  are  separated  by  a  porous  dia- 
phragm, there  is  a  mutual  transfer  of  the  liquids  in  distinct  ratios, 
according  to  time,  either  by  what  is  called  endosmosis,  or  by  a  dif- 
fusion ;  and  the  rate  of  transfer  is  materially  affected  by  a  galvanic 
current  passing  through  them.  From  observations  and  operations 
made  on  a  large  scale,  and  from  experiments  on  various  kinds  of 

*  Philosophical  Transactions,  Part  I.  for  1844. 
\ 


THEORETICAL   OBSERVATIONS.  631 

solutions,  we  believe  that  the  fractional  transfers  of  Professors 
Daniell  and  Miller  are  the  results  of  endosmosis  or  diffusion,  and 
not  of  electrolytic  transfer.  According  to  recent  experiments  by 
Professor  Graham,  diffusion  takes  place  in  definite  proportions. 
We  believe  that  no  transfer  of  any  base  or  positive  element  takes 
place  by  electrolysis. 

PROPOSED  THEORY. — Having  carefully  considered  the  various 
phenomena  attending  electrolysis,  in  the  decomposition  of  metallic 
salts,  we  think  that  the  electricity  is  conducted  through  the  solu- 
tion by  the  base,  or  positive  element,  in  the  electrolyte,  which  it 
does  as  if  it  was  a  solid  chain  of  particles — or  wire.  We  have 
already  said,  that  if  to  a  solution  of  sulphate  of  copper  we  put  a 
piece  of  iron,  the  acid  in  union  with  the  copper  will  leave  it  and 
combine  with  the  iron.  If  a  piece  of  copper  be  put  into  the  same 
solution,  no  change  will  take  place ;  but  if  we  by  any  means  give 
to  this  copper  an  increased  tendency  to  unite  with  the  acid,  it  will 
attract  the  acid  from  the  copper  in  solution  by  virtue  of  this  in- 
creased attraction.  Suppose  two  wires  coming  from  a  battery  are 

Fig.  592. 


placed  in  a  solution  of  sulphate  of  copper,  thus,  (Fig.  592):  the 
double  row  representing  the  compound  atoms  of  sulphate  of  copper 
forming  the  electrolyte :  C  C  the  copper  or  positive  element,  and 
SO*  the  sulphuric  acid  or  negative  element  of  the  solution.  The 
two  single  rows  C  C,  etc.,  at  each  end  of  the  double  row,  represent 
the  wire  or  solid  conductors  of  the  electricity,  from  the  battery  to 
the  decomposition  cell :  the  last  particle  of  the  single  rows  p  n 
nearest  the  double  row  may  be  viewed  as  the  electrodes.  The 
sulphuric  acid  SO4,  and  the  copper  C,  in  solution,  are  held  together 
by  their  affinity  for  each  other. 

Now  let  it  be  supposed  that  an  equivalent  of  electricity-  leave* 
the  positive  terminal  of  the  battery  P,  and  passes  along  the  solid 
particles  of  the  conductor,  that  particle  upon  which  the  electricity 
is,  must  be  for  the  time  in  a  higher  state  of  excitement  than  the 
other  particles.  When  the  electric  current  comes  to  the  last  par- 
ticle of  the  solid  chain  p,  which  is  in  contact  with  the  electrolyte, 
its  increased  excitement  causes  it  to  attract  and  combine  with  the 
acid  particle  SO4  nearest  it ;  the  electricity  being  dynamic,  passes 


632  THE   PRACTICAL   METAL-WORKER'S   ASSISTANT. 

to  the  first  basic  particle  Cl,  giving  it  an  exalted  excitement,  which 
causes  it  to  unite  with  the  acid  particle  SO4 2,  the  electric  force 
passing  to  02,  which  becomes  excited  in  turn,  and  takes  the  par- 
ticles SO4 3  ;  and  so  on4hrough  the  chain  till  the  last  particle  05, 
which,  having  no  further  acid  to  combine  with,  gives  its  electricity 
to  the  solid  conductor,  or  electrode  n,  and  passes  along  to  the  bat- 
tery, the  particle  Co  being  thus  left  adhering  to  the  solid  chain  of 
particles,  or  electrode. 

By  this  we  observe  that  every  equivalent  of  decomposition  will 
carry  an  equivalent  of  acid  to  the  positive  electrode,  without  taking 
the  metallic  element  to  the  other  or  opposite  electrode.  This  is 
exactly  the  fact  of  the  case,  the  result  that  takes  place  in  all  solu- 
tions undergoing  decomposition  by  the  current,  and  also  in  the 
battery  between  the  zinc  and  copper.  In  these  explanations  we 
have  spoken  of  electricity  as  a  material  substance,  passing  along 
the  line,  being  more  easily  conceived  than  the  theory  of  vibra- 
tions, etc. ;  but  the  effects  are  the  same,  and  we  have  seen  no  phe- 
nomena in  electric  decomposition  which  are  inconsistent  with  the 
views  here  given. 


INDEX. 


Acid,  nitric,  for  dipping,  593. 

Acid,  nitric,  for  dissolving  silver,  588. 

Action  of   sulphate  of   copper  upon 

iron,  628. 
Adhering  of  electrotypes  to  monlds, 

prevention  of,  502. 
Advantages  of  cast-iron,  25. 
Advantages  of  electro-plating,  605. 
Advice  to  capitalists,  by  Smee,  554. 
Air  furnaces,  87. 
Air  furnaces,  small   construction   of, 

222. 

Airo-hydrogen  blow-pipe,  338,  350. 
Air  pumps,  88. 
Alchemists,  43. 
Alchemy,  18. 

Alkalimeter  test  for  cyanide  of  potas- 
sium, 601. 

Alkalies  as  fluxes,  43. 
Alkalies,  metals  which   form,  have  a 

tendency  to  unite  with  those  which 

form  acids,  29. 
Alkali,  preparation   of,  for  removing 

grease  and  oil,  579. 
Alloy  fusible  for  moulds,  540. 
Alloy  of  silver,  copper  and  iron,  592. 
Alloy  of  the  standard  measure  used  by 

government,  203. 
Alloy  of  zinc  and  mercury,  556. 
Alloys,  28, 144. 

Alloys  and  their  melting  heats,  334. 
Alloys,  cohesion  of,  214. 
Alloys,  deposition  of,  622. 
Alloys,  experiments  with,  226. 
Alloys,  fusibility  of,  217. 
Alloys,  gold,  190. 
Alloys,  hardness,   fracture  and  color 

of,  210. 

Alloys,  hardness  of,  30. 
Alloys   having  specific   gravity  more 

than  the  mean  of  their  components, 

207. 
Alloys,  having    specific   gravity  less 

than  the  mean  of  their  components, 

207. 
Alloys,   malleability  and  ductility   of, 

212. 

Alloys,  mixing,  222,  224. 
Alloys  more  fusible  thau  the  individual 

metals,  30. 


Alloys  most  used,  179. 
Alloys  of  copper  and  lead,  186. 
Alloys  of  copper  and  tin,  185. 
Alloys  of  copper  and  zinc,  183. 
Alloys  of  copper,  zinc,  tin  and  lead, 

187. 

Alloys,  remarks  on  characters  of,  210. 
Alloys,  separation  of  the  constituents 

of,  31. 

Alloys,  silver,  199. 
Alloys,  solution  for  depositing,  622. 
Alloys,  weighing,  215. 
Aluminium,  619. 
Amalgamation,  economy  of  zinc  plates, 

512. 
Amalgamation,  experiments  upon  the 

economy  of,  512. 

Amalgamation,  how  often  needful.  537. 
Amalgamation,  its  advantages,  513. 
Amalgamation  of  zinc  for  batteries, 

511. 

Amalgam,  an,  29. 
Analysis  of  black  matter  upon  positive 

electrode,  520. 

Analysis  of  efflorescence,  536. 
Analysis  of  refined  iron,  72. 
Analysis  of  steel  and  iron,  145. 
Analysis  of  steel  and  iron,  Kegnault's 

mode,  145. 
Anchors,  88. 

Ancient  alloys  of  copper  and  tin,  485. 
Angle  and  surface  joints,  292. 
Angular  screw  threads,  434. 
Annealing  of  glass,  146. 
Annealing  of  wire,  323. 
Anodes  anions  of  battery,  509. 
Anti-attrition  metal,  Babbitt's,  203. 
Anti-friction  cam-press,  Dick's,  369. 
Anti-friction  metal,  Fenton's,  203. 
Antimony,  28,  179,  180. 
Antimony,  curious  phenomenon  in  de- 
positing of,  622. 
Antimony,  deposition  of,  619. 
Antimony,  melting  of,  221. 
Anvils,  hardening  of,  154. 
Apparatus,  forms  of,  for  electrotyping, 

535. 

Applications  of  coating  with  copper,563. 
Arrangements  for  plating  in  factories, 

594. 

633 


634 


INDEX. 


Arsenic,  28. 

Arsenic,  deposition  of,  619. 

Articles  prepared  for  plating,  how,  593. 

Artificial  and  natural  blasts,  50. 

Atmospheric  air,  applications  of,  to  fluid 

metal,  69. 
Atmospheric  air,  contact  of  iron  with, 

in  purification,  21. 
Atmospheric  air,  forcing,  into  the  fluid 

metal,  71. 
Attraction  of  acids  for  metals,  table  of, 

575. 

Aurate  of  ammonia,  611. 
Avoirdupois,  table  for  converting  de- 
cimal proportions  into  divisions  of 

the  pound,  216. 
Axle  of    wheel   carriages,   known  to 

assume  the  crystalline  state,  26. 
Axletrees,  hardening  wrought  iron,  158. 

Babbitt's  anti-attrition  metal,  203. 

Babington's  battery,  517. 

Ball  and  cross  of  St.  Paul's  Cathedral, 

309. 

Bright  red  heat,  96. 
Ball,  iron,  87. 
Bank  of  England,  Oldham's  process  of 

annealing    boxes     containing    steel 

plates,  150. 

Bar  iron,  manufacture  of,  115. 
Barron  and  Brothers'  furnace,  229. 
Batteries,  of,  98. 
Batteries,  comparative  constancy  of 

different  kinds,  552. 
Batteries,  comparative  produce,  553. 
Batteries,  comparative  cost  of,  554. 
Batteries  connected  against  each  other, 

580. 

Batteries,  description  of,  509. 
Batteries,  of  different  metals,  516. 
Batteries,  relative  intensity  of,  559. 
Batteries,  relative  power  of,  552. 
Batteries,   respective  peculiarities   of, 

509. 

Batteries,  round,  used  for  plating,  596. 
Batteries,  single    pair,   properties   of 

metals  fit  for,  515. 
Battery,  Babington's,  517. 
Battery,  Bunseu's,  526. 
Battery,  Daniell's,  522. 
Battery,  depositing  by  separate,  550. 
Battery,  description  of,  510. 
Battery,  formed  by  solution  of  silver, 

600. 

Battery,  Grove's,  524. 
Battery,  single  pair,  510. 
Battery,  single  pair,  different  elements, 

Battery,  single  pair,  distance  between 
plates,  513. 


Battery,  Smee's,  527. 

Battery,  solutions  of,  how  often  changed, 

Battery,  solutions,  the  comparative 
value  of,  536. 

Battery,  the  earth,  529. 

Battery,  the  first,  490. 

Battery,  use  of,  separate,  505. 

Battery,  Wollaston's  common  acid,  de- 
fects of,  519. 

Battery,  Wollaston's,  518. 

Battery, Wollaston's,  modification,  518. 

Battery,  process  for  making  solutions, 
589,  611. 

Bawtree,  Mr.,  550. 

Beak  irons,  287. 

Bearings  for  locomotives,  tin  and  pew- 
ter, 235. 

Belgian  furnace,  41. 

Belly  helve,  112. 

Bellows,  88. 

Bellows  for  hand  forging,  93. 

Bells,  casting,  267. 

Bending  thin  metals,  288. 

Berlin  ornaments  of  iron,  275. 

Bessemer's  address  to  the  British  Asso- 
ciation, 74. 

Bessemer's  apparatus,  description  of,  62. 

Bessemer's  experiments  at  Baxter 
house,  126. 

Bessemer's  iron,  analysis  of,  71. 

Bessemer's  iron,  fibrous  stratum  in,  73. 

Bessemer's  iron,  test  of,  73. 

Bessemer's  modification  of  steam  ham- 
mers, 70. 

Bessemer's  process,  hammering  and 
squeesing  in,  73. 

Bessemer's  iron,  extreme  tenacity  of,  73. 

Bessemer's  iron,  phosphorus  in,  72. 

Bessemer's  process,  change  effected  in 
iron  by,  72. 

Bessemer's  process  of  refining  iron,  22, 
60. 

Bessemer's  process,  removal  of  carbon 
and  silicon  by,  72. 

Bessemer's  process  to  take  advantage 
of  the  impurities  of  iron  uniting  with 
oxygen,  71. 

Bessemer's  squeezers,  69. 

Besson's  screw  lathe,  443. 

Best  method  of  making  silver  solu- 
tions, 589. 

Binding  screws,  varieties  of,  532. 

Bismuth,  18,  28,  179,  181. 

Bismuth,  depositiou  of,  619. 

Bits,  drilling,  407. 

Black  leading  non-metallic  moulds,  505. 

Black  matter  upon  positive  electrode, 
520. 

Black  lead  as  a  conductor,  505. 


INDEX. 


Black  red  heat,  96. 

Black  appearance  of  gold  pole,  614. 

Blast,  88. 

Blast,  chain,  55. 

Blast-furnaces,  44. 

Blast  machines,  52. 

Blasts,  natural  and  artificial,  50. 

Blistered  steel,  84. 

Blistered  steel  welding,  139. 

Bloom  iron,  87. 

Blowing  apparatus,  52. 

Blowing  cylinder,  effective  power  of,  52. 

Blow-pipes  in  soldering,  335. 

Bolts,  103-4. 

Bolt  screwing  machine,  437. 

Boiler-makers,  shears  for,  365. 

Borax  as  a  flux,  43. 

Boring  machines,  405. 

Book  covers  electrotyped,  563. 

Brace,  French,  404. 

Brads  and  nails,  cut,  386. 

Branson,  Dr.  F.,  on  ferns  and  sea  weeds, 
541. 

Brass,  225. 

Brass  and  gun  metal  castings,  pickling 
of,  276. 

Brass  filings,  loss  in  melting,  226. 

Brass  guns,  moulding,  267. 

Brass,  ordinary  yellow,  188. 

Brass  tubes  for  boilers  of  locomotives, 
329. 

Brass  and  copper,  raised  works  in 
sheet,  315. 

Brass  and  copper  soldering,  331. 

Brass,  depositing  of,  624. 

Braziers'  hearth,  335. 

Brick  dust  in  moulding,  241. 

Bright  plating,  how  done,  603. 

Britannia  metal,  224. 

Britannia  metal,  soldering,  334. 

British  mint,  application  of  a  wire- 
drawing process  in,  327. 

Brittleness  of  metals,  208. 

Broach,  for  philosophical  instruments, 
414. 

Broach,  Kinselaugh's,  414. 

Broaches  for  gun  barrels,  414. 

Broaches  for  making  taper  holes,  413. 

Bronze,  deposition  of,  627. 

Bronze  powder  used  as  a  conducting 
medium,  504. 

Bronzing,  black,  573. 

Bronzing,  brown,  573. 

Bronzing,  green,  574. 

Bronzing,  varieties  of,  572. 

Bruce's  type  founding  machine,  236. 

Brugnatelli's  experiments  on  deposi- 
tion, 491. 

Brushes  for  scratching  plated  goods, 
593. 


Bruns'  battle  of  Arbello  in  relievo,  316. 

Brushing  silver  off  copper  goods,  597. 

Building  up  or  welding,  97. 

Bullet  moulds,  232. 

Burnishing  of  plated  and  gilded  goods, 

593. 

Busts  and  figures,  how  made,  548. 
Button  metals,  soldering,  333. 
Buttons,  manufacture  of,  with  a  fly 


Cadmium,  28. 

Cadmium,  depositing  of,  519. 

Cagniardelle,  description  of,  56. 

Calcination  and  roasting,  36.         «..£) 

Calculating  machine,  axes  or  shafts  for. 
325. 

Calico,  covering  iron  rollers  with  cop- 
per, 564. 

Calico-printers'  rollers,  564. 

Calico-printers'  rollers,  etching  of,  564. 

Calico-printers,  cylinders  for,  253. 

Calico-printing,  plates  of  wire,  326. 

Cannon,  wrought  iron  for,  117. 

Carbon  in  iron,  71. 

Carbon  and  oxygen,  union  of,  in  Besse- 
mer's  process,  68. 

Carbonates  as  fluxes,  43. 

Carbonic  acid  gas,  47". 

Carbonic  oxide  gas,  47. 

Carburetted  hydrogen  gas,  47. 

Case-hardening,  147. 

Case-hardening,  wrought  and  cast  iron, 
164.  . 

Cast-iron,  advantages  of,  25. 

Cast  and  wrought  iron,  difference  in,  21 . 

Cast  and  wrought  iron,  hardening,  163. 

Casting  brass  guns,  268. 

Casting  equestrian  and  other  figures, 
251. 

Casting  figures,  249. 

Cast-steel,  84,  139. 

Casting  and  founding,  230. 

Castings,  patterns  for,  iron,  261. 

Catalan  trompe,  54. 

Catalan  trompe,  action  of,  55. 

Catalonia  trompe,  used  in,  54. 

Cathode,  cations,  509. 

Cave's  punch  improvement,  389. 

Chain  blast,  55. 

Chain  blast,  construction  of,  55. 

Chain  blast,  air-chamber  of,  55. 

Chains,  gilt,  quantity  of  gold  required, 
617. 

Chains,  manufacture  of,  381. 

Chains,  welding  of,  136. 

Chamfered  drills,  395. 

Chamfering  of  screw-taps,  423. 

Change  wheels  for  screws,  calculations 
of  any  combination  of,  451 


INDEX. 


Change  wheels  for  screw-cutting,  449. 

Charcoal,  46. 

Charcoal  iron,  20,  83. 

Chased  works  in  sheet  metal,  315. 

Chasing,  the  art  of,  316. 

Chasing  tool,  453. 

Chemical  affinities,  39. 

Chemical  analysis,  importance  of,Jn 
showing  the  composition  of  iron,  71. 

Chemical  combinations,  liberate  heat, 
30. 

Chemical  part  of  metallurgy,  39. 

Chemical  vessels,  coated  with  copper, 
objections  to,  568. 

Chemistry,  metallurgic,  17. 

Chemistry  in  soldering,  331. 

Chemistry,  its  aid  in  smelting,  42. 

Chemistry,  production  and  utilization 
of  metals  allied  with,  18. 

Chemistry  rests  on  a  basis  of  metallur- 
gic aspirations  and  empiricism,  18. 

Chimney  draught,  sacrifice  of  fuel  in, 

Chill  castings,  256. 

Chilled-iron  castings,  difficulties  of 
making,  163. 

China  sauce-pans  lined  by  electrotype, 
568. 

Chisels,  139. 

Chisels,  hardening  of,  153. 

Chloride  of  silver  dissolved  in  cyanide 
of  potassium,  589. 

Chlorides,  39. 

Chlorides,  reduction  of,  39^ 

Chlorous  and  zincous,  proposed  terms 
for  electrode,  etc.,  509. 

Chronometer,  balance  springs,  156. 

Chucking  and  reaming  lathes,  469. 

Circular  saws,  flattening,  320. 

Circular  works  spun  in  the  lathe,  300. 

Cistern  of  Catalan  trompe,  54. 

Claims  of  originality  made  by  experi- 
menters, 506. 

Clay  coated  with  copper,  504. 

Clays,  process  of  refining,  59. 

Classification  of  metals,  27. 

Cleaning  articles  for  plating,  593. 

Cleaning  of  silver,  610. 

Cleaning  powders,  610. 

Clocks,  pinions  of,  325. 

Cloth,  covered  with  copper,  563. 

Coal,  46. 

Coal-smelted  iron  inferior  to  charcoal 
iron,  20. 

Coal-smelted  iron,  sulphur  and  phos- 
phorus in,  20. 

Coating  cloth,  563. 

Coating  cornice  carvings,  563. 

Coating  glass  and  porcelain,  568. 

Coating  iron  with  copper,  574,  579. 


Coating  metals  with  nickel,  618. 

Coating  metals  with  palladium,  618. 

Coating  metals  with  platinum,  617. 

Coating  of  figures  with  copper,  545. 

Coating  of  flowers,  548. 

Coating  other  metals  upon  cast-iron, 
581. 

Coating  terra  cotta,  563. 

Cobalt,  28. 

Coffee-pots  of  sheet  metal,  310. 

Cohesion  of  alloys,  214. 

Cohesion  of  matter,  40. 

Cohesive  force,  diminution  of,  40. 

Cohesive  force  of  solid  bodies,  table  of. 
204. 

Coin,  discs  of  metal  for,  cut  with  fly- 
press,  380. 

Coin,  how  to  make  a  copy  of,  534. 

Coke,  46. 

Coke  or  charcoal  preferable  to  coal  for 
steel,  148. 

Cold,  rolling  of  metals,  when,  278. 

Cold  short' iron,  82. 

Coloring  of  gilding,  614. 

Color  of  alloys,  210. 

Combustible  gases,  utilization  of,  48. 

Combustion,  45. 

Combustion  of  gas,  47. 

Common  acid  batteries  :  their  defects, 
519. 

Comparative  cost  of  different  batteries, 
554. 

Comparative  produce  of  different  bat- 
teries, 553. 

Comparative  value  of  common  salt,  sal 
ammoniac,  537. 

Comparative  value  of  exciting  solu- 
tions, 517,  536. 

Comparative  value  of  sulphate  of  zinc 
and  sulphuric  acid,  537. 

Composition  for  taking  casts  in  elastic 
moulds,  549. 

Compound  cell  process  for  electro- 
typing,  556. 

Conditions  required  in  gilding,  612. 

Conducting  power  of  metals,  515. 

Conducting  power  of  solutions,  579. 

Conduction,  illustration  of,  580. 

Conduction  of  metals,  effect  of,  in  bat- 
tery, 515. 

Cone,  the,  in  sheet  metal,  283. 

Constancy  of  batteries,  experiments  on, 
552. 

Constant  battery,  523. 

Converting  vessel,  Bessemer's,  63. 

Converting  vessel,  Bessemer's,  interior 
of,  64. 

Copper,  18,  28,  179,  181. 

Copper  and  brass,  raised  works  in 
sheet,  315. 


IXDEX. 


63T 


Copper  and  brass  soldering1,  331.    • 

Copper  and  lead  alloys,  186. 

Copper  and  iron  plates,  experiment  on 

the  power  required  to  force  a  punch 

through,  390. 

Copper  and  tin  alloys,  ancient,  185. 
Copper  and  tin,  alloys  of,  185. 
Copper  and  zinc,  alloys  of,  183. 
Copper  and  zinc,  combination  of,  225. 
Copper  and  zinc  when  melted  together 

produce  a  high  temperature,  30. 
Copper  cloth,  563. 
Copper  deposited  on  lead,  503. 
Copper  from  ores  by  battery,  526. 
Copper,  fuel  for  forging,  94. 
Copper,  impurities  in,  used  for  elec- 
trodes, 521. 

Copper,  melting  of.  221. 
Copper  mould  dissolved  from  silver, 

607. 
Copper  »mould,    protection    of,   from 

silver  deposit,  607. 

Copper  moulds  from  plaster  models,  544. 
Copper,  quantity  deposited  on  square 

foot  of  cloth,  563. 
Copper  soldering,  333. 
Copper  solutions  for  coating  iron,  577. 
Copper  solutions,  how  made,  533. 
Copper  stereotypes,  504. 
Copper,  zinc,  tin  and  lead  alloys,  187. 
Coppering  an  iron  shaft,  580. 
Copper-plate  engraving,   copying    of, 

568. 

Copying  copperplate  engravings,  568. 
Core-boxes,  246. 
Cores  for  moulding,  241,  247. 
Cored  works,  moulding,  245. 
Coring,  examples  of,  247. 
Cort's  improvements  in  refining  of  iron, 

20,  21,  22. 

Cost  of  compound  cell  process,  556. 
Cost  of  different  batteries,  553. 
Covering  iron  with  zinc,  583. 
Cracks  and_distortions  in  steel  avoided 

by  proper  manipulation,  151. 
Crank  forging,  120. 
Crane,  110. 
Creasing  tool,  287. 
Crook-bit  tongs,  91. 
Crucibles  for  cyanide  of  potassium,  576. 
Crucibles  for  melting  metals,  221. 
Cruikshanks'  battery,  517. 
Crystalline  structure  of  wrought-iron, 

125. 

Crystallization  of  iron,  116,  123. 
Crystallization  of  iron,  Mallet  on,  124. 
Crystallizing  tendency  of  wrought-iron 

in  large  masses,  26. 
Crystals  of   sulphate    of   copper    on 

electrodes,  562. 


Cutter  bars,  410. 

Cutter  stock,  439. 

Cutters  to  assist  the  action  of  dies  for 
screws,  434. 

Cutting  of  works  in  sheet  metal,  286. 

Cutting  nippers  for  wires,  352. 

Cyanide  fumes,  effects  of  breathing, 
upon  health,  615. 

Cyanide  of  copper  by  adding  cyanide 
of  potassium  to  oxide  of  copper,  577. 

Cyanide  of  copper  by  adding  cyanide 
of  potassium  to  sulphate  of  copper, 
577. 

Cyanide  of  copper  from  ferrocyanide 
of  copper,  578. 

Cyanide  of  copper,  modes  of  prepara- 
tion, 577. 

Cyanide  of  potassium,  cost  of  manu- 
facture, 576. 

Cyanide  of  potassium,  mode  of  pre- 
paring, 575. 

Cyanide  of  potassium,  impurities  of, 
576. 

Cyanide  of  potassium,  precautions  re- 
quired in  making,  576. 

Cyanide  of  potassium,  quantity  for  100 
ounces  of  silver,  589. 

Cyanide  of  silver  by  dissolving  chloride 
of  silver  in  Cy.  K.,  589. 

Cyanide  of  silver  by  dissolving  oxide 
of  silver  in  Cy.  K.,  588. 

Cyanide  of  silver  dissolved  in  yellow 
prussiate  of  potash,  588. 

Cyanide  of  silver,  preparation  of,  587. 

Cyanide  solution,  decompositions,  597. 

Cyanide  solutions,  peculiarity  of,  578. 

Cylinder,  effective  power  of  blowing, 

Cylinders  in  sheet  metal,  282. 
Cylindrical  holes,  broaches  for,  414. 
Cylindrical  wire,  325. 

Dalton,  Dr.,  on  the  ductility  and  mal- 
leability of  metals,  279. 

Daguerreotypes,  electrotyping  of,  550. 

Damascus  gun  barrels,  135. 

Daniell's  and  Miller's  experiments  on 
Electrolysis,  630. 

Daniell's  battery,  how  constructed, 
522. 

Daniell's  battery,  properties  of,  522. 

Daniell's  experiments  on  depositing, 
492. 

Daniell's  nomenclature,  509. 

Dannemora  mines,  Sweden,  83. 

Davy,  Sir  Humphrey,  24. 

Dead  silvering  upon  medals.  609. 

Deck  beams  of  iron  ships,  171. 

Decks  of  iron  ships,  171. 

Decomposition  cell,  524. 


IXDEX. 


Decomposition  effected  by  the  battery, 

490. 
Decomposition  effected    by  the    pile, 

490. 
Decomposition   of  cyanide    solutions, 

597.   • 
Decomposition   of    metallic  sulphides 

when  heated  without  access  of  at- 
mospheric air,  34. 

Decomposition  of  plating  solution,  597. 
Deer's  fat  and  suet,  545,  548. 
Defects  in  batteries,  519. 
Degrees  of  heat,  94. 
De  La  Rive  and  Spencer's  failure  in 

gilding,  cause  of,  575. 
De  la  Rue,  494,  556. 
Dented  iron,  83. 

Deposit,  dissolving  of,  in  solutions,  599. 
Deposit,  how  to  make,  a  non-metallic 

mould,  545. 
Deposit,  how  to  prevent  adhesion  of; 

534. 

Deposit,  non-adherence  of,  581. 
Deposit  on  battery  coppers,  520. 
Deposited  metal,  quantity  of,  depend- 
ing on  thickness  of  plaster,  499. 
Depositing  by  separate  battery,  550. 
Depositing  lead,  iron  and  tin,  619. 
Depositing  silver,  607. 
Deposition  of  alloys,  622. 
Deposition  ef  bronze,  627. 
Deposition  of  metals  on  one  another, 

574. 
Deposition  of  one  metal  on  another, 

491. 
Deposition  on  other  metals  as  coatings, 

617. 
Depositions  in  large  moulds  or  objects, 

547. 
Dickerson's  method  of  making  wrought- 

iron  directly  from  the  ores,  75. 
Dick's  anti-friction  cam-press,  369. 
Dies,  hardening  of,  154. 
Dies,    Holtzapffels',     regulating     for 

screws,  487. 
Dies  for  raised  works  in  sheet  metal, 

311. 

Dies  for  screws,  433. 
Die  stock,  436. 
Die-stocks,  427. 

Different  densities,  effects  of,  562. 
Different  densities  of  solution,  562,  598. 
Different  metals  used  for  plating,  603. 
Dilations  of  metals  by  heat,  208. 
Dipping  articles  in  acid  for  plating,  593. 
Dipping  in  nitrate  of  mercury,  593. 
Dipping  partially  coated  articles,  596. 
Dirck's,  Mr.,  notices  of  Jo 


496. 


notices  of  Jordan's  claims, 


Discovery  of  electro-metallurgy,  492. 


Discovery  of  electro-metallurgy,  Smee's 
opinion,  492. 

Dissolving  copper  moulds  from  silver. 
607. 

Dissolving  gold  from  gilt  articles,  614. 

Dissolving  off  deposited  metal  in  solu- 
tion, 559. 

Dissolving  silver  from  copper,  597. 

Distance  between  battery  plates,  513. 

Distance,  experiments  upon,  513. 

Distillation  of  mercury  from  zinc,  556. 

Dividing  engines,  Ramsden's,  461. 

Drawing  down,  97,  102. 

Drawing  for  glyphography,  564. 

Drawing  metal  tubes,  327. 

Draw  plates  for  wire,  323. 

Drawing  wires,  322. 

Drill  of  the  Lowell  machine  shop,  390. 

Drills,  392. 

Drills,  hardening  of,  153. 

Drills,  methods  of  working,  ,by  hand 
power,  397. 

Drills  for  metals  used  by  hand,  392. 

Drill-stocks,  399. 

Drilling  and  boring  machines,  405. 

Drop  shot,  new  method  of  manufac- 
turing, 276. 

Drying  articles  from  solution,  592. 

Dry  process  for  reduction  of  metallic 
oxides,  32. 

Dry  sand  moulds,  256. 

Ductility  and  malleability  of  alloys, 
212. 

Ductility  and  malleability  of  metals, 
Dr.  Dalton  on,  279. 

Ductility  of  metals,  208. 

Ductility  of  tin,  329. 

Ductility,  processes  dependent  on,  322. 

Durability  of  iron  ships,  178. 

Early  deposition  of  metals,  491. 

Earth  and  Wollaston's  battery  com- 
pared, 529. 

Earth  battery,  properties  of,  529. 

Economy  of  amalgamating  zincs,  512. 

Economy  of  iron  ships,  178. 

Edges  of  plates  in  flattening,  320. 

Effects  of  conducting  power  of  solu- 
tions and  metals,  579. 

Effects  of  conduction  for  a  protection 
coating,  586. 

Effect  of  cyanogen  on  health,  615. 

Effects  of  decomposition  of  cyanide 
solutions,  598. 

Effects  of  different  densities  of  solu- 
tions, 562,  598. 

Effects  of  light  upon  silver  solutions, 
592. 

Effects  of  resistance  in  batteries,  557. 

Effects  of  size  of  electrodes,  595. 


INDEX. 


639 


Efflorescence  in  porous  cells,  536. 

Elastic  moulding,  544. 

Elastic  moulding,  to  make  figures  by, 

549. 

Elasticity  of  springs,  cause  of,  157. 
Electric  acid,  491. 
Electricity  from  sandy  deposits,  604. 
Electricity  from  vats,  600. 
Electricity  viewed  as  an  acid  (electric 

acid),  491. 
Electrodes,  crystals    of   sulphate    of 

copper  upon,  562. 
Electrodes,  definition  of,  509. 
Electrodes,   relative  size  and  effects, 

595. 

Electrodes,  size  of,  552. 
Electrodes,  unequal  action  upon,  613. 
Electro-decompositions,  how  affecting 

the  discovery  of  electro-metallurgy, 

491. 
Electro-decompositions,  early  opinions 

of,  491. 

Electro-gilding,  610. 
Electro-gilding,  objections  to,  605. 
Electro-metallurgy,  first  published  de- 
scription of,  493. 

Electro-metallurgy,  its  discovery,  492. 
Electro-metallurgy,  Smee's  opinion  of 

its  discovery,  492. 

Electro-metallurgy,  works  upon,  508. 
Electro- metallurgy,  name  first  applied, 

508. 

Electro-plating,  solutions  for,  587. 
Electro-plating,  advantages  of,  605. 
Electro-plating,  objections  to,  615. 
Electro-plating,  587. 
Electro  relations  of  metals  in  different 

solutions,  514. 

Electrolysis,  DanielPs  theory  of,  630. 
Electrolysis,  Faraday's  theory  of,  628. 
Electrolysis,  Graham's  theory,  629. 
Electrolysis,  proposed  theory  of,  631. 
Electrolyte,  510. 
Electrotype  processes,  533. 
Electrotype,  Spencer's  first  paper  upon, 

497. 
Electrotypes     from     daguerreotypes, 

550. 
Electrotyping,  forms  of  apparatus  for, 

535. 

Electrotyping  leaves  and  ferns,  541. 
Elements,  different,  of  batteries,  513. 
Elements  of  electrolytes,  non-transfer 

of.  561. 

Klkington's  patent  for  silvering,  508. 
Eisner  upon  galvanic  soldering,  569. 
Enamelling  by  galvanism,  571. 
Encyclopedia  Metropolitana  on  found- 
ing, 269. 
Endosmosis  of  solution,  630 


Engineers'   shearing    tools,    generally 

worked  by  steam,  364. 
English  zinc  oven,  42. 
Engraved  copper  plates,  copying  of, 

568. 

Engraving  by  galvanism,  494. 
Engraving,      Perkins's      process    for 

transfer,  159,  161. 
Equestrian  figures,  casting,  251. 
Etchiug,  experiments  on,  500. 
Evils    of    dipping    articles    partially 

coated  with  silver,  596. 
Exciting  solutions  for  batteries,  com- 
parative value  of,  536. 
Experiments    on  galvanic    soldering, 

569. 
Experiments    upon    distance,   battery 

plates,  513. 
Expansion  metal,  203. 

Fairbairn's  experiments  on  compara- 
tive merits  of  wood  and  iron  for 
ship  building,  177. 

Fairbairn's  experiments  in  iron  ships 
on  canals,  167. 

Fairbairn's  experiments  on  joints  for 
iron  ships,.  174. 

Fallacy  of  the  compound  cell  system, 
556. 

Faraday  and  Stoddart's  discovery  of 
silver  steel,  29. 

Faraday's  nomenclature,  509. 

Faraday's  report  to  Harbour  of  Refuge 
Commissioners,  585. 

Faraday's  theory  of  electrolysis,  628. 

Fenton's  anti-friction  metal,  203. 

Ferrocyanide  of  copper  to  make  solu- 
tion, 578.  »  .; 

Ferns,  how  to  copy,  541. 

Figure  casting,  249. 

Figures  and  busts,  how  made,  548. 

Figures,  covering,  with  copper,  545. 

Figures  from  elastic  moulds,  549. 

Figures,  moulding  of,  545. 

File  making,  precautions  against  clink- 
ing, 158. 

Filling  the  moulds,  252. 

Fire,  95. 

Fire  bricks,  selection  of,  109. 

Fire,  management  of,  94. 

First  printed  description  of  electro- 
metallurgy, 494. 

Flasks,  iron  founders',  254. 

Flasks  or  casting-boxes,  240. 

Flat-bit  tongs,  90. 

Flattening  of  thin  plates  of  metal,  300. 

Flattening  saws,  319,  320. 

Flowers,  coating  of,  548. 

Fluxing,  42. 

Fluxes,  20,  42,  334. 


640 


INDEX. 


Fly  presses,  punches  used  in,  377. 

Forks  and  spoons  plated  by  old  pro- 
cess, 605. 

Forge  for  hand  forging,  93. 

Forge,  pig  iron,  82. 

Forged  tools,  description  of,  108. 

Forged  work  subjected  to  welding 
heat,  96. 

Forging  in  large  masses,  deteriorating 
effects  of,  129. 

Forging  of  iron  and  steel,  86. 

Forging,  ordinary  practice  of,  97. 

Founding,  230. 

Founding,  Encyclopedia  Metropolitana 
on,  269. 

Foundry  moulds,  240. 

Fourcroy,  491. 

Fowling  pieces,  barrels  for,  135. 

Fracture  of  alloys,  210. 

Frames  and  ribs  of  an  iron  ship,  170. 

Francis's  metallic  life-boats,  295. 

Franklin  Institute,  report  on  the  Prince- 
ton gun,  128. 

Free  oxygen  required  for  the  removal 
of  sulphur,  34. 

French  horn,  bell  of,  310. 

Fuel  for  smith's  forge,  94. 

Fullers,  top,  98. 

Furnace,  Belgian,  41. 

Furnace,  Dickerson's,  75. 

Furnace,  mercury  distillation,  41. 

Furnaces  for  melting  metals,  220. 

Furnaces  for  mixing  metals,  Barren's, 
229. 

Furnace,  reverberating,  108. 

Furnaces,  44. 

Furnaces  for  gold  and  silver  refining, 
222.  , 

Furnaces  for  soldering,  335. 

Fusee  engines,  444. 

Fusible  metal  moulds,  540. 

Fusible  metal  moulds  from  plaster,  544. 

Fusible  metals,  melting,  220. 

Fusibility  of  alloys,  30,  217. 

Fusibility  of  metals,  207. 

Fusibility,  relative,  of  metals,  as  a 
means  of  classification,  28. 

Galena,  when  heated  without  the  ac- 
cess of  atmospheric  air,  suffers  par- 
tial decomposition,  34. 

Galvanic  action  between  the  silver  and 
copper  in  dipping,  596. 

Galvanic  principles  and  rate  of  protec- 
tion, 585. 

Galvanic  protection  of  metals,  579. 

Galvanic  protection,  none  in  the  air, 
506. 

Galvanic  soldering,  569. 

Galvanometers,  533. 


Galvano-plastic  niello,  571. 

Gases,  composition  of,  47. 

Gases,  utilization  of  combustible,  48. 

Gear  cutting  machine,  439. 

German  silver,  depositing  of,  624. 

Gilding  by  mercury,  615. 

Gilding,  electro,  610. 

Gilding  e^ectrotyped  daguerreotypes, 
550. 

Gilding,  how  to  regulate  the  color  of, 
614. 

Gilding  in  1805,  Brugnatelli's  experi- 
ments, 491. 

Gilding,  practical  suggestions  on,  617. 

Gilding,  process  of,  612. 

Gilt  articles,  coloring  of,  614. 

Glass  and  porcelain,  coating  of,  568. 

Glass  and  steel,  analogy  between,  146. 

Glass,  preparation  of,  for  coating,  568. 

Glyphography,  564. 

Glyphography,  instruction  in,  566. 

Gold,  28,  179,  189. 

Gold  alloys,  190. 

Gold  and  platinum,  18. 

Gold  and  silver,  refining  furnaces  for, 
222. 

Gold,  dissolving,  from  gilt  articles, 
614. 

Gold  leaf  used  as  a  conductor,  505. 

Gold,  melting  of,  221. 

Gold,  preparing  solution  of,  611. 

Gold,  quantity  necessary  to  deposit  on 
some  articles,  617. 

Gold,  reduction  of,  by  phosphorus,  548. 

Gold  soldering,  333. 

Gold,  strength  of  solution,  how  main- 
tained, 613. 

Gouges,  hardening  of,  153. 

Government  standard  measure  alloy, 
203. 

Graham's  green  bronze,  574. 

Graham's,  Prof.,  nomenclature,  509. 

Graham's  theory  of  electrolysis,  629. 

Grandjean's  lathe  for  screws  (1729), 
443. 

Grantham  on  iron  ships,  178. 

Green  sand  moulds,  256. 

Grove's  battery,  how  constructed,  524. 

Grove's  battery,  defects  of,  526. 

Grove's  battery,  properties  of,  525. 

Guide-screw  elements,  practice  in 
originating,  466. 

Gun  barrels,  broaches  for,  414. 

Gun,  Mersey  steel  company's  wrought- 
iron,  129. 

Gun  metal,  188. 

Gun  metal  castings,  pickling  of,  276. 

Guns,  brass,  moulding,  267. 

Gun  lock  springs  fried  in  oil  in  tem- 
pering, 156. 


INDEX. 


6U 


Gutta  percha  moulds,  541. 

Gutta  percha  used  as  a  varnish,  568. 

Gutta  percha  in  the  marine  glue,  541. 

Hammer  hardened  steel,  85. 

Hammer,  Nasmyth  steam,  111,  112. 

Hammer,  works  raised  by  the,  302. 

Hammers,  99,  139. 

Hammers  for  working  wrought-iron  in 
large  masses,  111. 

Hammers,  set,  98. 

Hammers,  tilt  and  trip,  143. 

Hammer-tongs,  91. 

Hammering,  100. 

Hammering  and  squeezing  of  iron  in 
Bessemer's  process,  73. 

Hand  forging,  88,  93. 

Hardening  and  tempering,  144. 

Hardening    and    tempering,   common 
examples  of,  153. 

Hardening  and  tempering  steel,  prac- 
tice of,  147. 

Hardening,  less  common  examples  of, 
158. 

Hardening,    precautionary    measures, 
158. 

Hardness  of  alloys,  210. 

Hardness  of  metals,  208. 

Hard  hammering,  crystallization  from, 
129. 

Hard  soldering,  examples  of,  339. 

Hatchet  stake,  287. 

Hatchets,  forging  of,  138. 

Heading  tools,  application  of,~140. 

Health,  effects  on,  of  breathing  cyano- 
gen fumes,  615. 

Health,  effects  on,  of  the  mercury  gild- 
ing, 615. 

Healey's  screw-cutter,  445.' 

Heat,  black  red,  low  red,  bright  red, 
white  welding,  96. 

Heat,  degrees  of,  94. 

Heat,  deficiency  of,  preferable  to  an 
excess  of,  in  working  steel,  149. 

Heat,  highest  known,  yielded  byjron 
blast  furnaces,  44. 

Heat,  modes  of  applying,  in  soldering, 
334,  335. 

Heat,  power  of  metals  for  conducting, 
208. 

Heated  air,  tendency  of,  50. 

Heating  of  iron  and  steel  to  soften  and 
make  malleable,  95. 

Heating  of  iron  for  rolling-mills,  118. 

Heavy  metafs,  classification  of,  27. 

Heavy  metals,  only,  that  the  metallur- 
gist has  to  do  with,  27. 

Heavy  works  in  iron,  87. 

Helix,  416. 

Hemispheres  of  metal,  309 
41 


Hindley's  screw,  427. 

Historical    anomaly    relative    to    the 

discovery  of  the  art  of  electro-metal- 
lurgy, 496. 

History  of  metallurgy,  19. 
History  of  the  art  of  electro-metallurgy, 

489. 
Holtzapffel's   screw  cutting  apparatus, 

450. 
HoltzapfFel's    taps,    dies,    hobs,     and 

screw  tools,  485. 
Hoop  tongs,  91. 
Hot  blast,  88. 

Hot  short  iron  brittle  when  heated,  95. 
Hydraulic   machines   for    cutting  off' 

copper  bolts,  368. 
Hydraulic  press  in  manufacturing  lead 

pipes,  330. 
Hydrogen  gas,  47. 
Hydrostatic  blast,  5o. 
Hydrostatic  presses,  tubes  of,  136. 
Hyposulphite  of  silver  solution,  590. 
Hyposulphite  of  soda,  preparation  of, 

591. 

Illustration  of  conduction,  580. 
Impurities  in  cyanide  of  potassium,  576. 
Impurities  in  iron,  21,  77. 
Impurities  in  iron,  combination  of,  with 

oxygen,  at  high  temperatures,  71. 
Impurities  in  sulphate  of  copper,  533. 
Influences  of  galvanism  in  protecting 

metals,  585. 

Ingot  hammering  on  a  suage,  70. 
Ingot  moulds,  preparation  of,  69. 
Inkstands,  pewter,  moulding,  233. 
Instruction  to  amateurs  in  glyphogra- 

phy,  566. 

Intensity  explained,  558. 
Intensity  tables  of  relative  batteries, 

559. 

Iridium  and  platinum,  29. 
Iron,  18,  28. 
Iron,  action  with  sulphate  of  copper, 

575,  628. 
Iron  and  copper  plates,  experiments 

on  the  power  required  to  force  a 

punch  through,  390. 
Iron  and  steel,  analysis  of,  145. 
Iron  and  steel,  forging  of,  86. 
Iron  and  wood  for  ship-building,  175. 
Iron,  application  of,  to  ship-building, 

167. 

Iron,  bar,  manufacture  of,  115. 
Iron,  bar,  tensile  strain  of,  varieties 

of,  115. 

Iron,  bending  of,  83. 
Iron,  Berlin  ornaments  of,  275. 
Iron,  Bessemer's,  analysis  of,  71. 
Iron,  Bessemer's,  phosphorus  in,  72. 


642 


INDEX. 


Iron  bolts  and  nails  coated  and  driven 

into  wood,  581. 
Iron,  brittle,  83. 
Iron,  carbon  in,  71 
Iron,    case    hardening,    wrought   and 

cast,  164. 
Iron,  cast,  coating  with  other  metals, 

581. 

Iron  castings,  patterns  for,  261. 
Iron  castings,  pickling  of,  276. 
Iron,  change  effected  in,  by  Bessemer's 

process,  72. 
Iron,  charcoal,  83. 
Iron,  chemical  process  of  purification 

of,  21. 

Iron,  chilled  castings,  163. 
Iron-clad  vessels,  179. 
Iron  coated  with  copper,  574 
Iron  coated  with  platinum,  618. 
Iron  coated  with  zinc,  583. 
Iron,  coating  of  other  metals  with,  61 9. 
Iron,  combination  of  silica  and  other 

earthy  bases  with,  69. 
Iron,  Cort's,  Bessemer's,  Plant's,  and 

Uchatius'  improvements  in  refining, 

22,  23,  24. 

Iron,  crystallization  of,  116,  118,  123. 
Iron,  dented,  83. 
Iron,  effect  of  long  exposure  to  the 

heat,  117. 
Iron,  fibre  of,  83. 
Iron,  fibrous,  125. 
Iron  for  cannon,  116. 
Iron  for  manufacture  of  steel,  83. 
Iron    for  tin   plating  by    Bessemer's 

process,  73. 

Iron  founders'  flasks,  254. 
Iron,  fractures  of,  83. 
Iron,  gilding  of,  612. 
Iron,  hardening  wrought  and  cast,  163. 
Iron,  heavy  works  in,  87. 
Iron,  "  Hoop  L,"  83. 
Iron,  hot  short,  brittle  when  heated,  95. 
Iron,  impurities  in.  21,  71. 
Iron,  low-moor,  116. 
Iron,  malleable,  77. 
Iron,  malleable  castings,  164. 
Iron,  malleable,  production  of,  69. 
Iron,  melting  and  pouring,  269. 
Iron,  ocean  steamers  of,  practical  in- 
formation on,  169. 
Iron,  oxides  of,  33. 
Iron,  phosphorus  in,  71. 
Iron,  piling  of,  in  the  furnace,  119. 
Iron,  pneumatically  refined,  by  Besse- 
mer, 73. 

Iron,  preparation  of,  for  coating,  579. 
Iron,  pure,  without  puddling  furnace, 

Iron,  quality  of,  83. 


Iron,  refined,  analysis  of,  72. 
Iron,  refining  and  working  of,  75. 
Iron  rendered  fusible  by  the  presence 

of  carbon,  30. 
Iron,  scrap,  114. 
Iron,  selection  of,  83. 
Iron  shaft  covered  with  copper,  580. 
Iron  ships'  decks,  171. 
Iron  ships,  deterioration  of  joints  of, 

173. 

Iron  ships,  durability  of,  178. 
Iron  ships,  economy  of,  178. 
Iron  ships  for  sea-going  purposes,  early 

example  of,  167. 

Iron  ship,  frames  and  ribs  of,  170. 
Iron  ships,  keels,  171. 
Iron  ships,  riveting  the  plates  of,  172. 
Iron,  silicon  in,  71. 
Iron,  soldering,  334. 
Iron    solution    for    dissolving  copper 

from  silver,  607. 
Iron,  stub,  83, 
Iron,  sulphur  in,  71. 
Iron,  Swedish,  83. 
Iron,  tensil  strength  of,  117. 
Iron  vessels  of  war,  179. 
Iron,  welding  of,  121. 
Iron  wire,  assumes  crystalline  state, 

26. 

Iron  wire  drawn  after  coating,  581 
Iron  with  antimony  will  cut  glass,  31. 
Iron  worked  at  bright  red  and  white 

heats,  96. 

Iron,  works  on,  86. 
Iron,  wrought,  crystallizing  tendency 

in  large  masses,  26. 
Iron,  wrought,  in  large  masses,  107. 

Jacobi's  experiments  in  decomposition, 
493. 

Jacobi's,  Jordan's  and  Spencer's  re- 
spective claims  to  originality,  496. 

Jelly  moulds  in  sheet  metal,  311. 

Johnson  and  Airey's  experiments  on 
the  effects  of  iron  ships  upon  the 
ship's  compasses,  169. 

Joining  of  works  in  sheet  metal,  278. 

Joints,  angle  and  surface,  292. 

Joints  for  iron  ships,  Fairbairn's  ex- 
periments, 174. 

Joints,  form  of,  soldered,  332. 

Joints  of  iron  ships,  deterioration  of, 
173. 

Jordan's  experiments  qp  deposition, 
493. 

Jumping  or  setting  up,  97,  102. 

Keels  of  iron  ships,  171. 
Kind  of  solutions  to  be  used  for  coat- 
ing metals,  574. 


INDEX. 


643 


Lace  covered  with  copper,  563. 
Lacquer  for  plaster  moulds,  543. 
Laminating  rollers,  use  of,  279.' 
Lap-joints  for  iron  ships,  173. 
Large  forgings,  hollowuess  in,  127. 
Large  forgings  require  different  treat- 
ment according  to  shape  and  use, 

120. 

Large  objects,  deposition  on,  547. 
Lathes,  circular  works  spun  in  the,  300. 
Lathes  for  screws,  439,  440,  442. 
Laws  of  deposition,  506. 
Laws  of  deposition  claimed  by  Smee, 

507. 
Laws  relating  to  depositions  pointed 

out  by  Spencer,  500. 
Laws  to  be  observed  in  coating  one 

metal  with  another,  575. 
Lead,  18,  28, 144,  179,  193. 
Lead  and  copper  alloys,  186. 
Lead  as  an  element  in  batteries,  515. 
Lead,  coating  with,  619. 
Lead,  copper,  zinc  and  tin  alloys,  187. 
Lead,  gilding  upon,  612. 
Lead  moulds  from  wood  engravings, 

503. 

Lead  moulds,  how  prepared,  503. 
Lead  soldering,  331,  333,  334. 
Lead  pipe,  application  of  the  hydraulic 

press  in  manufacturing,  330. 
Leather,  depositing  upon,  for  printing, 

564. 
Leupold's   "Theatrum    Machiuarum," 

429. 

Lever  drill,  403. 

Life-boats,  Francis's  metallic,  295. 
Lift-hammer,  small,  92. 
Light  and  heavy,  classification  of  metals 

as,  27. 
Light,  effects  of,  upon  silver  solutions, 

592. 
Lines  upon  surface  of  deposited  metal, 

cause  of,  561,  598. 
Lithium,  the  lightest  known  solid  iu 

all  nature,  27. 

Loam  and  sand  for  moulds,  240. 
Loam  moulds,  256. 
Loam  moulding,  264. 
Locomotive  wheels  with  hardened  steel 

tires,  162. 

Loss  of  weight  by  dipping,  596. 
Lowell  machine  shop,  machines  manu- 
factured at,  388,  390,  391,  439,  469, 

470. 

Lowmoor  iron,  116. 
Low  red  heat,  96. 

Machine  for  moving  goods  while  being 

plated,  599. 
Magneto-electric  machine,  530. 


Magneto-electric   machine,  improved, 

530. 

Magnates,  making  off,  152. 
Maintaining  gold   solution  of  proper 

strength,  613. 
Mallet,  Mr.,  on  wrought-iron  in  large 

masses,  109. 
Mallet  on  the  crystallization  of  iron, 

124. 

Malleable  iron,  69,  82. 
Malleable  iron  castings,  164. 
Malleable  iron,  manufacture  of,  77. 
Malleable  iron,  pure,  82. 
Malleable  iron,  varieties  of,  82. 
Malleable  metals,  144. 
Malleability   and   ductility  of  alloys, 

212. 

Malleability  of  metals,  208,  278. 
Management  of  fire,  94. 
Management  of  the  furnace,  222. 
Mandrels,  143. 
Mandrels  for  screws,  440. 
Mandrel,  old  French,  440. 
Manganese,  28. 

Marine  glue  with  gutta  percha,  514. 
Marteau  frontal  hammer,  111. 
Martien's  process  of  refining,  58. 
Martien's  process  of  refining  iron,  24. 
Mason's  application  of  separate  battery, 

505. 
Materials  for  working  wrought-iron  in 

large  masses,  114. 

Meal  dust  or  flour  in  moulding,  241. 
Medal,  preparation  of,  for  depositing 

upon,  534. 

Medals,  dead,  silvering  of,  609. 
Medals,   their  conducting   powers   as 

affecting  deposit,  580. 
Melting  and  mixing  metals,  220. 
Melting  and  pouring  iron,  269. 
Melting  heats  of  alloys,  334. 
Mercury,  18,  28. 
Mercury  absorbed  by  zinc,  512. 
Mercury  dissolved  in  nitric  acid,  593. 
Mercury  distillation  furnace,  41. 
Mercury,  gilding  by  means  of,  615. 
Metal  moulds,  547. 
Mercury  recovery  from   waste   zincs, 

512,  556. 

Metallic  life-boats,  Francis's,  295. 
Metallic  moulds,  230. 
Metallic  ores  defined,  17. 
Metallic  oxides,  31. 
Metallic  oxides,  reduction  of,  32. 
Metallic  sulphides,  33. 
Metallic  views,  in  the  production  of, 

501. 

Metallurgic  chemistry,  17. 
Metallurgic  operations,  special,  39. 
Metallurgy,  history  of,  19. 


644 


INDEX. 


Metallurgy,  progress  of,  without  prin- 
ciples being  understood,  18. 

Metallurgy  the  source  of  chemistry, 
18,  23. 

Metals,  patterns  for  moulding,  240. 

Metal  tubes,  drawing,  327. 

Metal,  washing  and  cleansing,  from 
silica  and  other  earthy  bases,  69. 

Metals  alike  in  their  affinities  for 
oxygen  do  not  readily  combine,  29. 

Metals  and  alloys  most  commonly  used, 
179. 

Metals  and  alloys,  remarks  on  charac- 
ters of,  210. 

Metals,  bending  of,  279. 

Metals,  brittleness  of,  208. 

Metals,  classification  of,  127. 

Metals,  classification  as  light  and 
heavy,  27. 

Metals,  ductility  of,  208. 

Metals  for  founding,  temperature  of, 
233. 

Metals,  fusibility  of,  207. 

Metals,  gliding  amongst  the  particles 
of,  279. 

Metals,  hardness  of,  208. 

Metals  having  a  strong  tendency  to 
combine  with  oxygen,  28. 

Metals,  heavy,  only  that  the  metallur- 
gist has  to  do  with,  27. 

Metals,  linear  dilations  by  heat,  208. 

Metals,  malleability  of,  208. 

Metals,  melting  and  mixing,  220. 

Metals,  power  of,  for  conducting  heat, 

Metals,  properties  of,  fit  for  batteries, 
515. 

Metals,  relative  fusibility  of,  as  a 
means  of  classification,  28. 

Metals  requiring  no  flux  in  soldering, 
334. 

Metals,  tabular  view  of  the  properties 
of,  207. 

Metals,  tenacity  of,  208. 

Metals,  thin  elasticity  of,  279. 

Metals,  the  tendency  of  which  to  com- 
bine with  oxygen  is  slight,  28. 

Metals,  useful,  defined,  17. 

Metals  which  form  both  acids  and 
bases  by  combination  with  oxygen, 

Metals  whose  oxygen  compounds  are 
basic  or  have  the  property  of  bases, 

Method  of  working  cyanide  of  copper 

solution,  578. 

Millward's  magneto  machine,  530. 
Mitchell's  machine  for  motion,  598. 
Mixing  and  melting  metals.  220. 
Mixture  for  coloring  gold,  614. 


Mode  of  suspending  electrotypes,  560. 

Models  for  moulding,  243. 

Modern  copper  and  tin  alloys,  185. 

"  Monkey,"  89. 

Monster  gun,  dimensions  of,  123. 

Monster  gun,  forging  of,  122. 

Mortises,  105. 

Motion,  machine  for  producing,  599. 

Moulding  cored  works,  245. 

Moulding,  elastic,  how  made,  544. 

Moulding,  loam,  264. 

Moulding  of  figures,  545. 

Moulding  simple  objects,  238. 

Moulds,  238. 

Moulds,  directions  for  making,  538. 

Moulds,  filling,  252. 

Moulds  in  lead  from  wood  engravings, 
503. 

Moulds  in  lead,  how  prepared,  503. 

Moulds  in  plaster  from  plaster,  543. 

Moulds,  metallic,  230. 

Moulds,  non-metallic,  prepared  to  re- 
ceive deposits,  545. 

Moulds  of  copper  from  plaster,  544. 

Moulds  of  fusible  alloys  from  plaster, 
544. 

Moulds  of  green  sand,  dry  sand,  and 
loam,  256. 

Moulds  of  plaster  of  Paris  or  sand, 
236. 

Moulds  of  wax,  taken  from  plaster,  543. 

Moulds,  precautions  necessary  in  put- 
ting them  into  solutions,  547. 

Moulds,  preparation  of  wax  for,  539. 

Moulds,  substances  for  making,  538. 

Moulds  to  take  in  fusible  metal,  540. 

Moulds  to  take  in  gutta  percha,  541. 

Moulds  to  take  in  Plaster  of  Paris, 
539. 

Moulds  to  take  in  wax,  539. 

Mounts,  silver,  how  made,  604. 

Murray's,  Robert,  discovery  of  the  use 
of  plumbago,  505. 

Music  plates  of  wire,  326. 

Music,  printing  of,  564. 

Musket  barrels,  134. 

Nails  and  brads  cut,  386. 

Nasmyth's  experiment  with  wrought- 

iron  ordnance,  26. 
Nasmyth's  steam  hammer,  111,  112. 
Native  alloys,  29. 
Native  printing,  542. 
Natural  and  artificial  blasts,  50. 
Navy    of   the    United    States,   great 

strength  of,  179. 
Needles,  steel  wire  for,  323. 
Negative  pole,  509. 
Newton's  patent  for  coating  cast-iron, 

581. 


INDEX. 


645 


Nasmyth's  experiments,  125. 

Nicholson's  experiments,  491. 

Nickel,  28,  178,  195. 

Nickel,  coating  metals  with,  618. 

Nickel  coating,  use  of,  for  gas  pipes, 
619. 

Nippers  for  wires,  352. 

Nitric  acid  for  dipping  (dippers'  aqua- 
fortis), 593. 

Nitrogen,  47. 

Noble  metals,  17,  28,  32. 

Nomenclature,  509. 

Nomenclature,  Daniell's,  509. 

Nomenclature,  Faraday's,  509. 

Nomenclature,  Graham's,  509. 

Non-adherence  of  deposit,  581. 

Non-metallic  moulds,  preparation  of, 
for  deposits,  545. 

Non-transfer  of  elements  in  electroly- 
sis, 561. 

Norway  iron,  21. 

Nuts,  104,  477. 

Nuts,  elastic,  478. 

Nuts,  force  exerted  in  bursting,  477. 

Nuts  of  square  thread,  478. 

Objections  to  electro-gilding,  615. 
Objections  to  electro-plating,  606. 
Objections  to  silver  articles  made  by 

the  battery,  608. 
Observed  facts,  use  of,  493. 
Oil,  tallow,  wax,  and  resin  in  hardening 

steel,  155. 
Oldham's  system  of  hardening  rollers 

for  transferring  impressions  of  steel 

plates,  150. 

Old  method  of  gilding,  615. 
Old  method  of  plating,  604. 
Oliver  lift  hammer,  92. 
Opinions  concerning  electro-deposition, 

491. 
Opposite  currents  of  electricity  from 

vats,  600. 
Ordnance,  wrought-iron,  accident  with, 

in  U.  S.  Navy,  25. 
Ornaments,  how  made  and  applied  to 

old  plate,  604. 

Ostrander's  improved  machine  for  rott- 
ing sheet  metal  pipe,  29 
O'Tool's  pin  drill,  396. 
Oven,  English  zinc,  42. 
Overcoming  resistance  in  solution,  557. 
Oxyhydrogen  blow  pipe,  337. 
Oxide  as  a  solvent  of  earthy  bases,  68. 
Oxide,  fluid,  69. 
Oxide,  fusion  of,  in  Bessemer's  process, 

68. 

Oxide  of  silver,  588. 
Oxides,  metallic,  31. 
Oxides  of  iron,  33 


Oxidizable  metals,  225. 

Oxidized  silver,  609. 

Oxygen,  28. 

Oxygen,  free,  required  for  the  removal 
of  sulphur,  34. 

Oxygen,  metals/  having  a  strong  ten- 
dency to  combine  with,  28. 

Palladium,  179,  195. 

Palladium  and  Platinum,  29. 

Palladium,  coating  with,  618. 

Palladiumizing  process,  218. 

Palmer's  glyphography,  564. 

Partitions  in  battery  troughs,  519. 

Patent  for  coating  china  and  glass,  568. 

Patent  for  depositing  alloys,  623. 

Patent  for  electro-magneto  plating, 
530. 

Patent  for  extracting  copper  from  ores, 
625. 

Patents  for  electro-metallurgy,  508. 

Patterns,  moulders',  243. 

Patterns  for  iron  castings,  251. 

Patterns  for  moulding,  238. 

Patterson,  Dr.Thomas,  550. 

Pattinson's  crystallization  process,  31. 

Peat  charcoal,  94. 

Peat,  Recce's  process  for  smelting  iron 
with,  49. 

Peculiarity  in  depositing  copper  from 
cyanide  solution,  578. 

Pencil  case,  gold  required  to  gild,  617. 

Penknives,  hardening  of,  154. 

Perkins'  method  of  treating  steel 
plates,  147. 

Pewter  inkstands,  moulding,  233. 

Pewter  moulding,  233. 

Pewter  soldering,  331,  334. 

Philosophical  instruments,  broach  for, 
414. 

Phosphorus  in  Bessemer's  iron,  72. 

Phosphorus  in  iron,  71. 

Phosphorus  solution  for  reducing  gold 
and  silver,  548. 

Pickling  of  iron,  brass,  and  gun  metal 
castings,  276. 

Pig  iron,  quantity  of  required  for  pro- 
duction of  malleable  iron,  82. 

Pile,  chemical  decomposition,  490. 

Pinions  of  cloaks,  325. 

Pinion  wire,  325. 

Pins,  unannealed  wires  for,  324. 

Pipe,  machine  for  rolling  sheet  metal, 
291. 

Pipes,  casting  crooked,  267. 

Pitch  block  for  works  in  sheet  metal, 
315. 

Pitch  preparation  for  protecting  cop- 
per from  deposit,  608. 

Plant's  process  of  refining  iron,  23,  57. 


646 


INDEX. 


Plaster  of  Paris,  coated  with  copper, 

504. 

Plaster  of  Paris  moulds,  236. 
Plaster  of  Paris  moulds,  how  taken, 

539. 

Plaster  of  Paris  moulds  taken  from 
/  plaster  models,  543. 

Plated  metals,  working  of,  313. 

Plates,  riveting  of,  for  iron  ships,  172. 

Plating,  electro,  587. 

Plating  in  large  factories,  594. 

Plating,  metals  best  suited  for,  603. 

Plating,  old  method,  604. 

Plating,  practical  instructions  in,  594. 

Plating  solution,  how  prepared,  587. 

Platinum,  28,  179,  196. 

Platinum  as  an  element  in  batteries, 

515. 

Platinum,  coating  with,  617. 
Platinum,  nitro-muriate,  527. 
Platinum,  splutions  of,  617. 
Platinizing  silver,  527. 
Platinode,  509. 
Pliers,  91. 
Plumbago  as    a  conducting   medium 

discovered,  505. 
Plumbers'  ladle,  220. 
Poles,  positive  and  negative,  defined, 

509. 

Polygonal  figures  in  sheet  metal,  282. 
Porcelain  covered  with  copper,  568. 
Porous  cell,  depositions  in,  523. 
Porous  cells,  how  preserved,  523. 
Porous  vessel  and  diaphragm,  535. 
Portable  hand  drill,  469. 
Position  of  electrotypes  in  solutions, 

560. 

Positive  pole,  509. 
Potash,  prussiate  of,  use  of,  in  case 

hardening,  166. 

Potash,  sulphite,  how  prepared,  591. 
Potassium,  cyanide  of,  mode  and  cost 

of  preparing,  576. 
Pot  metal,    189. 
Pouring  iron,  269. 

Practical  instructions  in  plating,  594. 
Practical  objections  to  solid  deposit, 

Practical  suggestions  on  gilding,  617. 
Precautions  on  putting  moulds   into 

solution,  547. 
Preparation   of   articles    for  plating, 

593. 

Preparation  of  glyphotypes,  564. 
Preparation  of  non-metallic  moulds  for 

receiving  deposit,  545. 
Preparation,  silver,  587. 
Preparation  of  solutions  of  gold,  610. 
Preparation  of  transfer  paper,  567. 
Preventing  electrotypes  adhering,  502. 


Princeton,  wrought-iron  gun,  128. 

Principles  of  galvanic  protection,  579. 

Principles  on  which  metallurgic  pro- 
cesses are  based,  39. 

Printers'  type,  metals  for,  224. 

Printing  by  electrotypes,  564. 

Printing  by  electrotype  plates  pro- 
posed by  Spencer,  499,  503. 

Printing  by  glyphography,  566. 

Printing,  difficulty  experienced  in  fire- 
paring  plates  for,  499. 

Printing  of  leather  by  electrotypes, 
564. 

Prismatic  vessels  in  sheet  metal,  282. 

Process  of  gilding,  612. 

Processes  dependent  on  ductility,  322. 

Production  of  a  purer  iron  by  the  ap- 
plication of  atmospheric  air  to  the 
fluid  metal,  69. 

Properties  of  metals  fit  for  batteries, 
515. 

Properties  of  metals,  tabular  view  of 
the,  207. 

Protection  of  silver  coating,  593. 

Protection  of  silver  surface,  609. 

Prussiate  of  potash,  use  of,  in  case 
hardening,  166.  « 

Puddled  iron  preferable  to  scrap  iron 
for  forging,  118. 

Puddlers'  balls,  Winslow's  machine 
for  compressing  and  rolling,  77. 

Puddling,  77. 

Punches,  143,  370. 

Punching  and  shearing  machine,  366. 

Punches  used  in  fly  presses  and  their 
products,  377. 

Punches  used  without  guides,  370. 

Punches  used  with  simple  guides, 
374. 

Punching,  104. 

Punching  machinery  used  by  engineers. 
388. 

Pure  iron  will  bear  a  great  degree  of 
heat,  95. 

Pyrites,  iron,  melt  at  a  low  red  heat, 

Quality  of  magneto-machines,  523. 
Quality  of  metal  regulated  by  battery, 

594. 
Quantity  of  cyanide  of  potassium  to 

precipitate  100  ounces  of  silver,  589. 
Quantity    of   metals    deposited,    how 

known,  596. 
Quantity  of  nitric  acid  to  dissolve  100 

ounces  of  silver,  588. 

Railway  axles,  crystallization  of,  26. 
Raised  works  in  sheet-metal,  ornament- 
al, details  of,  310. 


INDEX. 


647 


Raised  works  in  sheet  metal,  peculiar 

methods  in  working,  313. 
Ramsden's   apparatus   for   originating 

screws,  462. 

Ramsden's  dividing-engine  (1777),  461. 
Rate  of  depositing  silver,  603. 
Razors,  hardening  of,  154. 
Recently-patented  refining  processes, 

57. 

Recovery  of  gold  from  solution,  615. 
Recovery  of  silver  from  solution,  592. 
Red  short  iron,  82. 
Reece's  patent  for  conversion  of  peat 

by  distillation,  49. 

Refined  iron,  analysis  of,  72.  t ,  ! 

Refining  and  working  of  iron,  75. 
Refining  processes,  22. 
Refining  processes,  recently  patented, 

Refining  vessel,  Besseraer's,  62. 
Regulating  the  color  of  gilding,  614. 
Relative  intensity  of  batteries,  559. 
Relative  power  of  batteries,  552. 
Relief,  sheet  works  in  high,  315. 
Removing  of  grease  or  oil  from  metals, 

579. 

Reptiles,  moulding  of,  542. 
Resistance,   effects  on  deposits,   551, 

557. 

Reverberatory  furnace,  108. 
Reverberatory    furnace    employed    in 

Oldham's  process  of  annealing  boxes 

of  steel  engravings,  159. 
Reversing  and  figure  casting,  249. 
Rhodium,  179,  198. 
Rhodium  and  platinum,  29. 
Ribs  and  frames  of  an  iron  ship,  170. 
Riveting  of  plates  of  iron  ships,  172. 
Riveting,  set,  287. 
Roasting  and  calcination,  36. 
Rollers  of  iron-works,  80. 
Rollers  for  printing.  564. 
Rosin  and  wax  moulds,  539. 
Rotary  shears  for  metal,  368. 
Russian  iron,  21,  115. 

St.  Paul's  Cathedral,  bell  and  cross  of, 
309. 

Sal  ammoniac,  solution  of,  for  batter- 
ies, 537. 

Salts  of  cyanide  of  copper  and  potas- 
sium, 576. 

Salts,  which  are  important  in  metallur- 
gy, 39. 

Salt,  solution  of,  for  batteries,  491. 

Sand  moulds,  236,  237. 

Sand  moulds,  iron  founders',  254. 

Sand  sprinkled  upon  iron,  96. 

Sand  used  for  scouring,  593. 

Sandy  deposit,  534. 


Sandy  deposit,  electricity  from,  604. 
Saws  and  springs  lose  their  elasticity, 

by  grinding  and  polishing,  156. 
Saws,  flattening,  319. 
Saws,  hardening  of,  155.        • 
Scales  on  steel  should  be  ground  off 

before  hardening,  152. 
Scissors  and  shears  for  soft,  flexible 

materials,  354. 
Scoriae  and  metal,  mixture  of,  by  vio- 

hfet  ebullition,  69. 
Scrap  iron,  114. 
Scrap  iron  generally  used  in  forging, 

119. 

Scrap  iron,  necessity  of  cleansing,  119. 
Scrap  iron  not  desirable  for  forging, 

118. 

Scrap  iron,  various  qualities  in,  118. 
Scratch  brushes,  593. 
Screw,  cohesive  strength  of  the  hold, 

474. 

Screw-cutter,  445. 
Screw-cutter  bar,  426. 
Screw-cutter,  Healey'a,  445. 
Screw-cutting  in  lathes  with  traversing 

lathes,  440,  442. 
Screw-cutting  tools,  416. 
Screw,  elementary  idea  of,  416. 
Screw,  helical  ridge  of  the  external, 

471. 

Screw-lathe,  earliest,  (1569),  443. 
Screw,  left-handed,  435. 
Screw-mandrel  lathe,  441. 
Screw-plates,  427. 
Screw-plate,  thickness  of  the,  428. 
Screw-shaft  forging,  120. 
Screw-stocks,  435. 
Screw-tangent,  427; 
Screw-tap,  O'Neal's,  422. 
Screw-tap,  original,  427. 
Screw-taps,  angle  for,  421. 
Screw-taps,  chamfering,  423. 
Screw-taps,  cylindrical,  426. 
Screw-taps,  half-round,  421. 
Screw-taps,  use  of,  425. 
Screw,  the  cohesive  strength  of  the 

bolt,  473. 
Screw-thread,    mechanical    power  of, 

473. 
Screw-threads,  approximate  values  of 

Holtzapffel's,  485.  <* 

Screw-threads,  considered  in   respect 

to  their  proportions,  form  and  gen- 
eral characters,  470. 
Screw-threads,  square  and  angular,  434. 
Screw-tool  cutter  or  hob,  427. 
Screw-tools  for  angular  threads,  453. 
Screw-tools  for  square  threads,  453. 
Screws,  accuracy  of,  461. 
Screws,  angular  cutting,  452. 


648 


INDEX. 


Screws  for  astronomical  purposes,  ap- 
paratus for  originating,  419. 
Screws,  apparatus  for  cutting  original, 

by  means  of  a  wedge  or  inclined 

plane  (1763),  459. 

Screws,  binding  or  attachment,  416. 
Screws,  change-wheels  for,  449. 
Screws,  common,  419. 
Screws  cut  by  hand  in  the  common 

lathe,  439. 
Screws,  cutting  internal  with  sffew- 

taps,  420. 

Screws,  dies  for,  433. 
Screws,  diversity  of,  416. 
Screws,  double,  triple,  and  quadruple, 

416. 
Screws,  early  contrivances  for  cutting, 

428. 

Screws,  hollow,  417. 
Screws,  internal  square  threads,  455. 
Screws,  large  master-tap  for,  432. 
Screws,  long,  433. 
Screws,  making  small,  428. 
Screws,  measures  and  relative  strength 

of,  472. 

Screws,  medium  master-tap  for,  432. 
Screws,  nuts  of  coarse,  481. 
Screws  of  exact  value,  463. 
Screws,  originating,  418. 
Screws,  regulating,  416. 
Screws,  Reid's   machine   for  cutting, 

460. 

Screws,  small  master-tap  for,  432. 
Screws,  table  for  angular  thread,  483. 
Screws,  table  for  small,  of  five  angular 

threads,  484. 
Screws,  tangent,  481. 
Screws,  the  use  of  the  inclined  knife  in 

cutting,  463. 
Screws,  threads  of,  419. 
Screws,  uniform  system  of  threads,  483. 
Screws,  various  modes  of  originating 

and  improving,  457. 
Screws,  Walsh's  cutter  for,  419. 
Screwing  bolts  in  the  lathe,  apparatus 

for,  456. 

Sea-weeds,  how  to  copy,  541. 
Silicium,  619. 
Set-hammers,  98. 
Set  off,  to  make,  101. 
Shaping-machine,  439. 
Shaw's  manual  of  electro-metallursrv 

508. 

Shears,  352. 
Shears  for  metal,  worked  by  manual 

power,  360. 
Shear  steel,  84, 139. 
Shear  steel  bears  the  highest  degree  of 

heat,  95. 
Sheet-metal,  hammers  used  in,  287. 


Sheet-metal  pipe,   improved  machine 

for  rolling,  291. 

Sheet-metal,  polygonal  figures  in,  282. 
Sheet-metal,  tools  used  in  working,  286. 
Sheet-metal,  works  in,  made  by  cutting, 

bending  and  joining,  281. 
Sheet-metal,  works  in,  made  by  joining, 

278. 
Sheet-metal,  works  in,  made  by  raising, 

300. 
Ship-building,  application  of  iron  to, 

167. 

Ships,  sheathing  of,  how  destroyed,  586. 
Shot-moulding,  232. 
Shutting  together  in  welding,  131. 
Silica,  42. 
Silicon  in  iron,  71. 
Silver,  28,  179,  198. 
Silver  alloys,  199. 

Silver  and  gold,  fuel  for  forging,  94. 
Silver  and  gold,  refining,  222. 
Silver  articles  made  by  battery,  607. 
Silver,  chloride  of,  dissolved  in  cyanide 

of  potassium,  587. 
Silver,  cleaning  of,  610. 
Silver,  curious  alloy  of,  592. 
Silvering,  dead,  upon  metals,  609. 
Silver  dissolved  in  acids,  587,  588. 
Silver,  hardness  of,  effected  by  battery, 

594. 

Silver,  hyposulphite  solution,  590. 
Silver,  made  by  electrotype,  objections 

to,  608. 

Silver,  melting  of,  221. 
Silver  mounts  in  the  old  process,  604. 
Silver,  oxide  of,  dissolved  in  cyanide  of 

potassium,  588. 
Silver,  platinizing,  527. 
Silver,  protection  of,  in  air,  609. 
Silver,  recovered  from  solutions,  592. 
Silver  salts,  reduced   by  phosphorus, 

548. 

Silver,  soldering,  333. 
Silver  solutions  for  plating,  587,  588, 

589. 

Silver  solution  for  making  solii  arti- 
cles, 607. 
Silver  steel,  29. 
Single  cell,  505. 

Single  cell,  experiments  with,  533 
Single  cell  operations,  533. 
Single  pair  of  plates,  510. 
Size  of  electrodes,  552. 
Smee's  advice  to  capitalists,  554. 
Smee's  battery,  compound,  528. 
Smee's  battery,  how  constructed,  527. 
Smee's  battery,  modifications  of,  528. 
Smee's  battery,  properties  of,  528. 
Smee's  claims  to  original  discovery  of 

the  laws  of  electro-deposition,  506. 


INDEX. 


649 


Smelting,  42. 

Soda,  hyposulphite,  preparation  of,  590. 

Soft  soldering,  333. 

Soft  soldering,  examples  of,  341. 

Soldered  joints,  332. 

Solders,  hard,  33L,  333. 

Solders,  soft,  331. 

Soldering,  331. 

Soldering  by  deposition,  569. 

Soldering,  chemistry  of,  331. 

Soldering,  general  remarks  and  tabular 
view,  331. 

Soldering,  hard,  examples  of,  339. 

Soldering  of  brass,  copper,  lead,  tin, 
pewter,  331. 

Soldering  per  se,  or  burning  together, 
334,  347. 

Soldering,  soft,  examples  of,  341. 

Solid  bodies,  tables  of  the  cohesive 
force  of,  204. 

Solid  silver  articles,  made  by  battery, 
607. 

Solutions,  best  sort  for  depositing  solid 
silver,  607. 

Solutions,  different  density  of,  562. 

Solutions  for  battery,  how  often 
changed,  537. 

Solutions  for  deposition  of  alloys,  622. 

Solutions  of  aluminium,  619. 

Solutions  of  gold  by  acid,  611. 

Solutions  of  gold  by  battery,  611. 

Solutions  of  gold,  preparation  of,  610. 

Solutions  of  silicum,  621. 

Solutions,  silver,  best  method  of  mak- 
ing, 589. 

Solutions,  silver,  for  amateurs,  590. 

Sources  of  defects  in  batteries,  511. 

Southwark  Bridge,  blocks  of  cast-iron 
in,  25. 

Spades,  139. 

Special  metallurgic  operations,  39. 

Speculum  metal,  334. 

Spelter  solder,  331,  333. 

Spencer  and  de  la  Rives's  failure  in 
gilding,  575. 

Spencer's,  Jacobi's,  and  Jordan's 
claims,  496. 

Spencer's  first  electrotype,  501. 

Spencer's  first  paper  on  electrotyping, 
effects  of  it,  when  first  published, 
496. 

Spencer,  his  first  experiments,  493. 

Spencer,  his  first  paper  upon  electro- 
typing,  495. 

Spencer's  manipulations  for  electro- 
types, 497. 

Springs  and  saws  lose  their  elasticity 
by  grinding  and  polishing,  156. 

Springs,  hardening  of,  155. 

Springs,  to  take  out  of  wire,  324. 


Square  screw-threads,  434. 

Squeezers,  Bessemer's,  69. 

Steam-boilers,  joints  for,  293. 

Steam-hammer,  Bessemer's,  modifica- 
tions of,  70. 

Stearine  for  moulds,  545. 

Steel  and  glass,  analogy  between,  146. 

Steel  and  iron,  analysis  of,  145. 

Steel  and  iron,  forging  of,  86. 

Steel,  "  blazing  off,"  153. 

Steel,  blistered,  84. 

Steel,  cast,  84. 

Steel,  cementation  of  iron,  84. 

Steel,  cracking  of,  when  suddenly 
cooled,  146. 

Steel,  degrees  of  heat  for,  96. 

Steel,  degrees  of  heat  in  working,  85. 

Steel,  draw-plates  for  wire  of,  323. 

Steel,  encasing  in  charcoal  powder,  147. 

Steel,  fracture  of,  85. 

Steel,  hack-hammering,  153. 

Steel,  hammer  hardened,  85. 

Steel,  hammer  hardening  of,  145. 

Steel,  hard  and  soft  conditions  of,  145. 

Steel,  hardened  tires  for  locomotive- 
wheels,  162. 

Steel,  heat  for  tempering,  152. 

Steel,  manufacture  of,  83. 

Steel-pens,  383. 

Steel-pens,  heating  of,  155. 

Steel,  practice  of  hardening  and  tem- 
pering, 147. 

Steel-shears,  84. 

Steel,  soldering,  334. 

Steel,  water  not  essential  in  hardening, 
147. 

Steel,  whilst  red-hot,  in  its  weakest 
condition,  151. 

Stereotyping  in  copper  by  electrotype, 
504. 

Strength  or  cohesion  of  alloys,  214. 

Strengths  of  various  screws,  472. 

Stripping  gold  from  gilt  articles,  614. 

Stripping  silver  from  copper,  597. 

Stub  gun-barrels,  135. 

Sturgeon's  art  of  electrotyping,  508. 

Substitute  for  silver  in  Smee's  battery, 
528. 

Sulphate  of  copper,  action  upon  iron, 
628. 

Sulphate  of  copper  and  cyanide  of 
potassium  mixed,  576. 

Sulphate  of  copper,  impurities,  533. 

Sulphate  of  zinc  for  batteries,  536,  537. 

Sulphate  of  zinc,  solution  for  coating, 
583. 

Sulphides,  34. 

Sulphides,  reduction  of,  34. 

Sulphite  of  potash,  preparation  of,  591. 

Sulphite  of  silver  solution,  591. 


INDEX. 


Sulphuric  acid  for  pickling  castings, 
276. 

Sulphuric  acid  for  batteries,  537. 

Sulphur,  all  metals  combine  with,  34. 

Sulphurand  phosphorus  in  coal-smelted 
iron,  20. 

Sulphur  causes  a  low  degree  of  fusi- 
bility, 34 

Sulphur,  combination  of,  with  oxygen, 
69. 

Sulphur,  driving  off,  from  iron,  69. 

Sulphur  in  iron,  71. 

Sulphur  in  metallurgic  operations,  94. 

Sulphurous  acid  gas,  formation  of,  69. 

Sulphurous  acid,  how  prepared,  592. 

Sulphuret  of  carbon,  used  for  bright 
plating,  603. 

Surface  joints,  272. 

Suspending  electrotypes,  mode  of,  560. 

Swage  bits  for  wire,  326. 

Swage  tool,  141,  287. 

Swedish  iron,  21,  83, 115. 

Swiss  drill,  393. 

Szentepeteri,  the  Hungarian  silver- 
smith, alto  relievo  in  copper,  316. 

Table  covers,  gilt,  563. 

Table  of  exciting  solutions  for  batter- 
ies, 537. 

Table  of  relative  intensity  of  batteries, 
559. 

Table  test  for  free  cyanide  of  potassium 
in  solutions,  602. 

Taking  silver  from  copper,  597. 

Tallow,  oil,  wax  and  resin,  in  harden- 
ing steel,  155. 

Tangent  screws,  427. 

Tangent  screw  and  ratchet,  461. 

Taper-holes,  broaches  for  making,  413. 

Taps,  cutting  internal  screws  with,  420. 

Tea-pots  of  sheet-metal,  310. 

Teeth  of  saws,  cutting  of,  383. 

Telescope-tubes,  328. 

Temperature  of  metal  for  founding, 
253. 

Tempering  and  hardening,  144. 

Tempering  small  objects  in  steel,  153. 

Tenacity  of  metals,  208. 

Tennant  helves,  111. 

Tensil  strength  of  iron,  117. 

Terrestrial  globes  in  sheet-metal,  281. 

Testing  cyanide  of  potassium  in  gold 
solution,  613. 

Tests  for  cyanide  of  potassium,  601. 

Thenard,  491. 

Theoretical  observations,  528. 

Theory  of  electrolysis  proposed,  631. 

Thimble,  gold  required  to  gild,  617. 

Thin  plates  of  metal,  flattening,  with 
the  hammer,  316. 


Threads,  angular.  480. 

Threads  of  screws,  470,  479. 

Threads,  square,  480. 

Threads,  uniform  system  of,  483. 

Tilt-hammer,  111,  143. 

Time  taken  by  different  batteries  to 

deposit  1  Ib.  of  copper,  553. 
Tin,  18,  28,  144,  179,  200. 
Tin  confervas,  phenomenon  of,  622. 
Tin,    copper,    zinc    and    lead    alloys, 

187. 

Tin,  depositing  of,  619. 
Tin,  ductility  of,  329. 
Tin,  gilding  upon.  612. 
Tin,  refining  of,  30. 
Tin,  soldering,  331. 
Tin,  solutions  of,  622. 
Tin  tubes,  330. 
Tinned  iron,  soldering,  334. 
Tinned  iron,  wire-screws  of,  419. 
Tinning,  334,  347. 
Tinning  of  metals,  217. 
Tongs,  crook-bit,  91. 
Tongs,  flat-bit,  90. 
Tongs,  hammer,  91. 
Tongs,  hoop,  91. 
Top-fullers,  98. 
Tools  and  methods  for  raised  works  in 

sheet  metal,  peculiarities  of,  313. 
Tools,   hardening    and    tempering   of, 

154. 
Transfer  engraving,  Perkins's  process, 

159. 
Transfer  of  elements   of  electrotype, 

629. 

Transfer  of  solutions,  629. 
Transfer  paper,  preparation  of,  567. 
Trip-hammer,  143. 
Trompe,  54. 
Tubal  Cain,  107. 
Tubes,  brass,  for  boilers  of  locomotives, 

329. 

Tubes,  drawing  metal,  327. 
Tubes,  tin,  330. 
Tubes,  welded,  136. 
Turning  tools,  hardening  of,  153. 
Tutenague,  203. 
Tuyeres,  94. 

Tuyeres,  Bessemer's,  64. 
Tuyere-blocks,  Bessemer's,  64. 
Twisted  gun-barrels,  135. 
Type  founding,  235. 
Type  founding  machine,  Bruce's,  236. 
Type  metal,  224. 

Uchatius's  process  of  refining  iron,  24, 

Unequal  action  upon  electrodes,  613. 
Uniform  cooling  of  forgings,  necessity 
of,  128. 


INDEX. 


651 


United  States,  great  strength  of  its 

navy,  179. 
Uranium,  28. 
Useful  metals  defined,  17. 
Use  of  dipping  in  nitrate  of  mercury, 

594. 

Use  of  intensity  in  batteries,  558. 
Use  of  metal  moulds,  547. 
Use  of  zinc  coating  for  iron,  584. 
Uses  of  observed  facts,  493. 

Van  Mons,  491. 

Vases  of  sheet  metal,  285,  310. 

Vauquelin,  491. 

Veins,  metallic,  501. 

Vessels  composed  of  iron  plates,  used 

on  canals,  167. 

Voltaic  pile,  how  constructed,  489. 
Volta's  discovery,  489. 

Walker's  manipulations,  508. 

Walsh's  cutter  for  screws,  419. 

War-vessels,  iron  as  a  material  for,  179. 

Waste  zinc,  recovery  of  mercury  from, 
556. 

Watch-case,  gilt,  how  much  gold  re- 
quired, 617. 

Watch-maker's  drills,  hardening,  153. 

Watch-springs,  156. 

Water-back,  88. 

Water  not  essential  in  hardening  steel, 
147. 

Wax  and  rosin,  539. 

Wax-moulds  taken  from  plaster  models, 
543. 

Wax,  oil,  tallow  and  resin  in  hardening 
steel,  153. 

Wax,  to  make  moulds  in,  539. 

Wax,  to  prepare  for  moulds,  539. 

Weight,  loss  of,  by  dipping,  596. 

Weight  of  silver  deposited,  how  ascer- 
tained, 596. 

Weight  of  wrought-iron,  steel,  copper 
and  brass-wire  and  plates,  209. 

Welded  tubes,  136. 

Welding,  105. 

Welding,  general  examples  of,  131. 

Welding  heat,  96. 

Welding  heavy  works,  133. 

Welding  of  chains,  136. 

Welding  of  iron,  97, 121. 

Welding  of  iron  and  steel,  139. 

Wet  process  for  reduction  of  metallic 
oxides,  32. 

Wheels  for  railways,  137. 

White  cast-iron,  82. 

White  heat,  96. 

White  or  button  solders,  333. 

Wind-furnaces,  44. 

Window  lead,  327. 


Winslow's  machine  for  compressing 
and  rolling  puddlers'  balls,  77. 

Wire,  annealing  of,  323. 

Wire  for  calico-printing  plates,  326. 

Wire,  iron,  coated,  579. 

Wire  pinion,  325. 

Wires,  drawing,  322. 

Wood  and  iron  for  ship-building,  175. 

Wollaston's  and  earth  battery,  com- 
pared, 530. 

Wo! last on's  battery,  518. 

Wollastou's  experiments  on  galvanism, 
492. 

Wollaston's  battery,  modification,  518. 

Wollaston's  process  of  hardening  plates 
for  bank-note  engraving,  161. 

Woolrich's  magneto-electric  machine, 
530. 

Working  drills  by  hand-power,  397. 

Work-shop  blow-pipe,  338. 

Works  in  sheet  metal  made  by  joining, 
278. 

Works  in  sheet  metal  made  by  raising, 
300. 

Works  published  upon  electro-metal- 
lurgy, 508. 

Works  raised  by  the  hammer,  302. 

Worm-wheel  cutter,  427. 

Wrought  and  cast-iron,  difference  in, 
21. 

Wrought  and  cast-iron,  hardening, 
163. 

Wrought  iron  almost  infusible,  21. 

Wrought-iron  axle-trees,  hardening  of, 
158. 

Wrought-iron,  change  in  the  structure 
of,  during  heating,  126. 

Wrought-iron,  chemical  or  molecular 
difficulty  in  large  masses,  26. 

Wrought-iron,  crystalline  structure  of, 
125. 

Wrought-iron,  crystallizing  tendency 
in  large  masses,  26. 

Wrought-iron,  danger  of  cold  hammer- 
ing, 130. 

Wrought-iron,  Dickerson's  method  of 
making,  75. 

Wrought-iron,  difficulty  of  welding 
large  masses,  26. 

Wrought-iron  for  cannon,  117. 

Wrought-iron,  fusing  of,  for  cranks, 
126. 

Wrodght-iron  gun,  bursting  of,  125. 

Wronght-iron  gun  of  the  Princeton, 
128. 

Wrought-iron  guns,  failure  of,  129. 

Wronght-iron  guns,  successful  manu- 
facture of,  129. 

Wrought-irou  hinges,  making,  134. 

Wrought-iron  in  large  masses,  107. 


652 


INDEX. 


Wrought-iron,  internal  rending  or  tear- 
ing of,  126. 

Wrought-iron  ordnance,  25,  26. 

Wrought-iron  ordnance,  large  piece 
made  in  Liverpool,  26. 

Wrought-iron  plates,  effects  of  shot 
on,  125. 

Wrought-iron,  practically  pure  iron, 
21. 

Wrought-iron  wheels  for  locomotives, 
137. 

bellow  brass,  188. 

Yellow  prussiate  of  potash  used  for 
dissolving  cyanide  of  silver,  588. 

Zinc,  18,28,  144,  179,  201. 
Zinc  and  copper,  alloys  of,  183. 
Zinc  and  copper,  combination  of,  225. 
Zinc  and  copper,  when  melted  together, 
produce  a  high  temperature,  30. 


Zinc,  tin,  copper  and  lead  alloys,  187, 
Zinc,  best  sort  for  batteries,  511. 
Zinc,  deposit  of,  in  black  lead,  584. 
Zinc,  how  often  the  plates  should  be 

amalgamated,  537. 
Zinc,   how  to  amalgamate   plates   of, 

511. 

Zinc,  mixing  with  another  metal,  225. 
Zinc  ovens,  English,  42. 
Zinc,  recovery  of  mercury  from,  556. 
Zinc,  reduced  in  battery,  510. 
Zinc,  soldering,  333,  334. 
Zinc,  solution  of,  for  coating  iron,  583. 
Zinc,  sulphate  solution  of,  for  batteries, 

537. 

Zinc,  use  of  a  coating  of,  583. 
Zinced  tin,  Dr.  Faraday's  opinion  of, 

584. 

Ziucode,  proposed  term,  509. 
Zincous  and  chlorous,  509. 


THE  END. 


ractical  ^ 


PUBLISHED   BT 

HENRY    CAREY    BAIRD, 

INDUSTRIAL     PUBLISHER, 

.      4O6      T7V7"  a,  1  xx  ox  t       S»  t  x-  o  o  t  . 

PHILADELPHIA. 


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Solids,  Plate  VII.  Rules  and  Practical  Data.  On  Coloring  Sections,  with 
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Plate  X..  Continuation  of  the  Study  of  Projections — Use  of  sections — de- 
tails of  machinery,  Plate  XI.  Simple  applications — spindles,  shafts, 
couplings,  wooden  patterns,  Plate  XII.  Method  of  constructing  a 
wooden  model  or  pattern  of  a  coupling,  Elementary  applications — 
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Strength  of  material,  Resistance  to  compression  or  crushing  force, 
Tensional  Resistance,  Resistance  to  flexure,  Resistance  to  torsion, 
Friction  of  surfaces  in  contact. 

THE  INTERSECTION  AND  DEVELOPMENT  OF  SURFACES,  WITH  AP- 
PLICATIONS.— The  Intersection  of  Cylinders  and  Cones,  Plate  XIV.  The 
Delineation  and  Development  of  Helices,  Screws  &nd  Serpentines,  Plate 

XV.  Application  of  the  helix— the  construction  of  a  staircase,  Plate 

XVI.  The  Intersection  of  surfaces — applications  to  stop-cocks,  Plate 

XVII.  Rules  and  Practical  Data—  Steam,  Unity  of  heat,  Heating  surface, 
Calculation  of  the  dimensions  of  boilers,  Dimensions  of  firegrates, 
Chimneys,  Safety-valves. 

THE  STUDY  AND  CONSTRUCTION  OF  TOOTHED  GEAR. — Involute,  cy- 
cloid, and  epicycloid,  Plates  XVIII.  and  XIX.  Involute,  Fig.  I,  Plate 

XVIII.  Cycloid,  Fig.  2,  Plate  XVIII.    External  epicycloid,  described 
by  a  circle  rolling  about  a  fixed  circle  inside  it,  Fig.  3,  Plate  XIX. 
Internal  epicycloid,  Fig.  2,  Plate  XIX.      Delineation  of  a  rack  and 
pinion  in  gear,  Fig.  4,  Plate  XVIII.    Gearing  of  a  worm  with  a  worm- 
wheel,  Figs.  6  and  6,  Plate  XVIII.    Cylindrical  or  Spur  Gearing,  Plate 

XIX.  Practical  delineation  of  a  couple  of  Spur-wheels,  Plate  XX. 
The  Delineation  and  Construction  of  Wooden  Patterns  for  Toothed  Wheels, 
Plate  XXI.    Rules  and  Practical  Data— Toothed  gearing,  Angular  and 
circumferential  velocity  of  wheels,  Dimensions  of  gearing,  Thickness 
of  the  teeth,  Pitch  of  the  teeth,  Dimensions  of  the  web,  Number  and 
dimensions  of  the  arms,  wooden  patterns. 

CONTINUATION  OF  THE  STUDY  OF  TOOTHED  GEAR. — Design  for  a 
pair  of  bevel-wheels  in  gear,  Plate  XXII.  Construction  of  wooden 
patterns  for  a  pair  of  bevel-wheels,  Plate  XXIII.  Involute  and 
Helical  Teeth,  Plate  XXIV.  Contrivances  for  obtaining  Differential 
Movements— The  delineation  of  eccentrics  and  cams,  Plate  XXV.  Rules 
and  Practical  Data—  Mechanical  work  of  effect,  The  simple  machines, 
Centre  of  gravity,  On  estimating  the  power  of  prime  movers,  Calcu- 
lation for  the  brake,  The  fall  of  bodies,  Momentum,  Central  forces. 

ELEMENTARY  PRINCIPLES  OF  SHADOWS. — Shadows  of  Prisms,  Pyra- 
mids and  Cylinders,  Plate  XXVI.  Principles  of  Shading,  Plate  XXVII. 
Continuation  of  the  Study  of  Shadows,  Plate  XXVIII.  Tuscan  Order, 
Plate  XXIX.  Rules  and  Practical  Data—  Pumps,  Hydrostatic  principles, 
Forcing  pumps,  Lifting  and  forcing  pumps,  The  Hydrostatic  press, 
Hydrostatical  calculations  and  data— discharge  of  water  through  dif- 
ferent orifices,  Gaging  of  a  water-course  of  uniform  section  and  fall, 
Velocity  of  the  bottom  of  water-courses,  Calculation  of  the  discharge 
ot  water  through  rectangular  orifices  of  narrow  edges,  Calculation  of 
the  discharge  of  water  through  overshot  outlets,  To  determine  the 
width  of  an  overshot  outlet,  To  determine  the  depth  of  the  outlet, 
Outlet  with  a  spout  or  duct. 

APPLICATION  OF  SHADOWS  TO  TOOTHED  GEAR,  Plate  XXX.  Ap- 
plication of  Shadows  to  Screws,  Plate  XXXI.  Application  of  Shadows  to 
Cfeto^V"14  ^  Furnace>  Plftte  XXXII.  Shading  in  Black— Shading  in 

THE  CUTTING  AND  SHAPING  OF  MASONRY,  Plate  XXXIV.     Rulet 

and  Practical  Data— Hydraulic  motors,  Undershot  water  wheels,  with 

ie  noats  and  a  circular  channel,  Width,  Diameter,  Velocity,  Num- 

•nd  capacity  of  the  buckets,  Useful  effect  of  the  water  wheel. 

Overshot  water  wheels,  Water  wheels  with  radial  floats,  Water  wheel 

With  curved  buckets,  Turbines.    Remarks  on  Machine  Tools. 


PUBLISHED  BY  HENRY  CAREY  BAIRD. 

THE  STUDY  OF  MACHINERY  AND  SKETCHING.— Various  applications 
and  combinations:  The  Sketching  of  Machinery,  Plates  XXXV.  and 
XXXVI.  Drilling  Machine;  Motive  Machines;  Wate.-  wheels,  Con- 
struction and  setting  up  of  water  wheels,  Delineation  of  water  wheels, 
Design  for  a  water  wheel,  Sketch  of  a  water  wheel ;  Overshot  Water 
Wheels.  Water  Pumps,  Plate  XXXVII.  Steam.  Motors;  High-pressure 
expansive  steam  engine,  Plates  XXXVIII.,  XXXIX.  and  XL.  Details 
of  Construction  ;  Movements  of  the  Distribution  and  Expansion  Valves  ; 
Rules  and  Practical  Data — Steam  engines  :  Low-pressure  condensing 
engines  without  expansion  valve,  Diameter  of  piston,  Velocities. 
Steam  pipes  and  passages,  Air-pump  and  condenser,  Cold-water  and 
feed-pumps,  High-pressure  expansive  engines,  Medium  pressure  con- 
densing and  expansive  steam  engine,  Conical  pendulum  o*  centrifugal 
governor. 

OBLIQUE  PROJECTIONS.— Application  of  rules  to  the  delineation  of 
an  oscillating  cylinder,  Plate  XLI. 

PARALLEL  PERSPECTIVE.— Principles  and  applications,  Plate  XLII. 

TRUE  PERSPECTIVE. — Elementary  principles,  Plate  XLIII.  Appli- 
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tion of  the  mill,  Representation  of  the  mill  in  perspective,  Notes  of 
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stone," Barnett's  millstone,  Hastie's  arrangement  for  driving  mills, 
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EXAMPLES  OF  FINISHED  DRAWINGS  OF  MACHINERY. — Plate  A, 
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Plate  I,  Duplex  steam  boiler ;  Plate  J,  Direct-acting  marine  engines. 

DRAWING  INSTRUMENTS. 

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3 


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Illustrated.  12mo.,  cloth, $1.75 

CONTENTS.— Sketch  of  the  Progress  of  Bookbinding,  Sheet- 
work,  Forwarding  the  Edges,  Marbling,  Gilding  the  Edges,  Covering, 
Half  Binding,  Blank  Binding,  Boarding,  Cloth-work,  Ornamental  Art, 
Finishing,  Taste  and  Design,  Styles,  Gilding,  Illuminated  Binding. 
Blind  Tooling,  Antique,  Coloring,  Marbling,  Uniform  Colors,  Gold 
Marbling,  Landscapes,  etc.,  Inlaid  Ornaments,  Harmony  of  Colors. 
Pasting  Down,  etc.,  Stamp  or  Press-work,  Restoring  the  Bindings  of 
Old  Books,  Supplying  imperfections  in  Old  Books,  Hints  to  Book  Col- 
lectors, Technical  Lessons. 

Booth  and   Morfit,     The   Encyclopedia  of 
Chemistry,  Practical  and  Theoretical : 

Embracing  its  application  to  the  Arts,  Metallurgy,  Mine- 
ralogy, Geology,  Medicine,  and  Pharmacy,  By  JAMES  C. 
BOOTH,  Melter  and  Refiner  in  the  United  States  Mint ; 
Professor  of  Applied  Chemistry  in  the  Franklin  Institute, 
etc.;  assisted  by  CAMPBELL  MOKFIT,  author  of  "Chemical 
Manipulations,"  etc.  7th  Edition.  Complete  in  one 
volume,  royal  octavo,  978  pages,  with  numerous  wood 

cuts  and  other  illustrations, $5.00 

From  the  very  large  number  of  articles  in  this  volume,  it  is  entirely 
impossible  to  give  a  list  of  the  Contents,  but  attention  may  be  called 
to  some  among  the  more  elaborate,  such  as  Affinity,  Alcoholometry, 
Ammonium,  Analysis,  Antimony,  Arsenic,  Blowpipes.  Cyanogen,  Dis- 
tillation, Electricity,  Ethyl,  Fermentation,  Iron,  Lead  and  Water. 


Brewer;  (The  Complete  Practical,) 

Or  Plain,  Concise,  and  Accurate  Instructions  in  the  Art 
of  Brewing  Beer,  Ale,  Porter,  etc.,  etc.,  and  the  Process 
of  Making  all  the  Small  Beers.  By  M.  LAFAYETTE  BYRX, 

M.  D.     With  Illustrations.     12rno $1.00 

"Many  an  old  brewer  will  find  in  this  book  valuable  hints  and  sug- 


PUBLISHED  BY  HENRY  CAREY  BAIRD. 

gestions  worthy  of  consideration,  and  the  novice  can  post  himself  up 
in  his  trade  in  all  its  parts."— 


Builder's  Pocket  Companion: 

Containing   the  Elements  of  Building,  Surveying,  and 
Architecture  ;  with  Practical  Rules  and  Instructions  con- 
nected with  the  subject.     By  A.  C.  SMEA.TON,  Civil  Engi- 
neer, etc.     In  one  volume,  12mo.,  ........................  $1.00 

CONTENTS.—  The  Builder,  Carpenter,  Joiner,  Mason,  Plasterer, 

Plumber,  Painter,  Smith,   Practical    Geometry,    Surveyor,  Cohesive 

Strength  of  Bodies,  Architect. 
"It  gives,  in  a  small  space,  the  most  thorough  directions  to  the 

builder,  from  the  laying  of  a  brick,  or  the  felling  of  a  tree,  up  to  the 

most  elaborate  production  of  ornamental  architecture.    It  is  scientific, 

without  being  obscure  and  unintelligible  ;  and  every  house-carpenter. 

master,  journeyman,  or   apprentice,  should   have  a  copy  at   hand 

always."  —  Evening  Bulletin, 

Byrne,    The  Handbook  for  the  Artisan,  Me- 
chanic, and  Engineer, 

Containing  Instructions  in  Grinding  and  Sharpening  of 
Cutting  Tools,  Figuration  of  Materials  by  Abrasion,  Lapi- 
dary Work,  Gem  and  Glass  Engraving,  Varnishing  and 
Lackering,   Abrasive    Processes,    etc.,    etc.      By   Oliver 
Byrne.     Illustrated  with  11  large  plates  and  185  cuts. 
8vo.,  cloth,  ........................................................  $5.00 

CONTENTS.—  Grinding  Cutting  Tools  on  the  Ordinary  Grind- 
stone ;  Sharpening  Cutting  Tools  on  the  Oilstone  ;  Setting  Razors  ; 
Sharpening  Cutting  Tools  with  Artificial.Grinders  ;  Production  of  Plane 
Surfaces'  by  Abrasion  :  Production  of  Cylindrical  Surfaces  by  Abra- 
sion ;  Production  of  Conical  Surfaces  by  Abrasion  ;  Production  of 
Spherical  Surfaces  by  Abrasion;  Glass  Cutting;  Lapidary  Work; 
Setting,  Cutting,  and  Polishing  Flat  and  Rounded  Works;  Cutting 
Faucets  ;  Lapidary  Apparatus  For  Amateurs  ;  Gem  and  Glass  Engrav- 
ing ;  Seal  and  Gem  Engraving;  Cameo  Cutting;  Glass  Engraving, 
Varnishing,  and  Lackering  ;  General  Remarks  upon  Abrasive  Pro- 
cesses Dictionary  of  Apparatus  ;  Materials  and  Processes  for  Grinding 
and  Polishing  commonly  employed  in  the  Mechanical  and  Useful  Arts. 

Byrne,    The  Practical  Metal-  worker's  Assist- 
ant, 

For  Tin-plate   Workers,  Braziers,    Coppersmiths,    Zinc- 
plate  Ornrmenters  and  Workers,  Wire  Workers,  White- 
smiths, Blacksmiths,  Bell  Hangers,  Jewellers,  Silver  and 
Gold  Smiths,  Electrotypers,   and  all  other  Workers  in 
Alloys  and  Metals.     Edited  by  OLIVEB  BYBWB.     Complete 
in  one  volume,  octavo,  ........................................  $7.50 

It  treats  of  Casting,  Founding,  and  Forging;  of  Tongs  and  other 
Tools;  Degrees  of  Heat  and  Management  of  Fires;  Welding  of 

6 


PRACTICAL  AND  SCIENTIFIC  BOOKS, 

Heading  and  Swage  Tools  ;  of  Punches  and  Anvils  ;  of  Hardening  and 
Tempering;  of  Malleable  Iron  Castings,  Case  Hardening,  Wrought 
and  Cast  Iron;  the  Management  and  Manipulation  of  Metals  and 
Alloys,  Melting  and  Mixing  ;  the  Management  of  Furnaces,  Casting 
and  Founding  with  Metallic  Moulds,  Joining  and  Working  Sheet  Metal ; 
Peculiarities  of  the  different  Tools  employed  ;  Processes  dependent  on 
the  ductility  of  Metals ;  Wire  Drawing,  Drawing  Metal  Tubes,  Solder- 
Ing  ;  The  use  of  the  Blowpipe,  and  every  other  known  Metal  Worker's 
Tool. 

Byrne,    The  Practical  Model  Calculator, 

For  the   Engineer,  Machinist,  Manufacturer   of  Engine 
Work,    Naval    Architect,    Miner,    and    Millwright.      By 
OLIVER  BYRNE,  Compiler  and  Editor  of  the  Dictionary  of 
Machines,  Mechanics,  Engine  Work  and  Engineering,  and 
Author  of  various  Mathematical  and  Mechanical  Works. 
Illustrated  by  numerous  engravings.     Complete  in  one 
large  volume,  octavo,  of  nearly  six  hundred  pages, ..$3.50 
The  principal  objects  of  this  work  are :  to  establish  model  calcula- 
tions to  guide  practical  men  and  students  ;  to  illustrate  every  practical 
rule  and  principle  by  numerical  calculations,  systematically  arranged  ; 
to  give  information  and  data  indispensable  to  those  for  whom  it  is  in- 
tended, thus  surpassing  in  value  any  other  book  of  its  character ;  to 
economize  the  labor  of  the  practical  man,  and  to  render  his  every-day 
calculations  easy  and  comprehensive.    It  will  be  found  to  be  one  of 
the  most  complete  and  valuable  practical  books  ever  published. 

Cabinetmaker's  and  Upholsterer's  Companion, 

Comprising  the  Rudiments  and  Principles  of  Cabinet- 
making  and  Upholstery,  with  Familiar  Instructions,  il- 
lustrated by  Examples  for  attaining  a  proficiency  in  the 
Art  of  Drawing,  as  applicable  to  Cabinet  Work;  the 
processes  of  Veneering,  Inlaying,  and  Buhl  Work  ;  the 
Art  of  Dyeing  and  Staining  Wood,  Bone,  Tortoise  Shell, 
etc.  Directions  for  Lackering,  Japanning,  and  Varnish- 
ing ;  to  make  French  Polish ;  to  prepare  the  best  Grlues, 
Cements,  and  Compositions,  and  a  number  of  Receipts 
particularly  useful  for  Workmen  generally.  By  J.  STOKES. 

In  one  volume,  12mo.     With  Illustrations, 75 

"  A  large  amount  of  practical  information,  of  great  service  to  all 
concerned  in  those  branches  of  business." — Ohio  State  Journal. 

Campion,    A  Practical  Treatise  on  Mechanical 
Engineering; 

Comprising  Metallurgy,  Moulding,  Casting,  Forging  Tools, 
Workshop  Machinery,  Mechanical  Manipulation,  Manu- 
facture of  Steam  Engine,  etc.,  etc.  Illustrated  with  28 
plates  of  Boilers,  Steam  Engines,  Workshop  Machinery, 


PUBLISHED   BY  HENRY  CAREY  BAIRD. 

etc.,  and  91  Wood  Engravings  ;  with  an  Appendix  on  the 
Analysis  of  Iron  and  Iron  Ores.  By  Francis  Campion, 
C.  E.,  President  of  the  Civil  and  Mechanical  Engineers' 
Society,  etc.  (In  press.) 

Celnart,    The  Perfumer, 

From  the  French  of  Madame  Celnart  ;  with  additions  by 
Professor  H.  Dussauce.  8vo.  (In press.) 

Colburn,    The  Locomotive  Engine ; 

Including  a  Description  of  its  Structure,  Rules  for  Esti- 
mating its  Capabilities,  and  Practical  Observations  on  its 
Construction  and  Management.  By  ZERAH  COLBURN.  Il- 
lustrated. A  new  edition.  12mo, 75 

"  It  is  the  moat  practical  and  generally  useful  work  on  the  Steam 
Engine  that  we  have  seen."— Boston  Trawler." 

Daguerreotypist  and  Photographer's  Companion, 

12mo.,  cloth, fl.OO 

Distiller  (The  Complete  Practical), 

By  M.  LAFAYETTE  BYRW,  M.D.  With  Illustrations.  12mo. 

$1.00 

"  So  simplified,  that  it  is  adapted  not  only  to  the  use  of  extensive 
Distillers,  but  for  every  farmer,  or  others  who  may  want  to  engage  in 
Distilling."— Banner  of  the  Union. 

Dussauce,    Practical  Treatise 

ON  THE  FABRICATION  OF  MATCHES,  GUN  COTTON,  AND  FULMI- 
NATING POWDERS.  By  Prof.  H.  Dussauce.  (In press.) 
CONTENTS.—  Phosphorus.—  History  of  Phosphorus;  Physical 
Properties ;  Chemical  Properties ;  Natural  State ;  Preparation  ot 
White  Phosphorus  ;  Amorphous  Phosphorus,  and  Benoxide  of  Lead. 
Motclies.— Preparation  of  Wooden  Matches ;  Matches  inflammable  by 
rubbing,  without  noise  ;  Common  Lucifer  Matches  :  Matches  without 
Phosphorus ;  Candle  Matches  ;  Matches  with  Amorphous  Phospho- 
rus ;  Matches  and  Rubbers  without  Phosphorus.  Gun  Cotton. — Proper- 
ties ;  Preparation  ;  Paper  Powder ;  use  of  Cotton  and  Paper  Powders 
lor  Fulminating  Primers,  etc.;  Preparation  of  Fulminating  Primers, 


Dussauce,    Chemical  Receipt  Book: 

A  General  Formulary  for  the  Fabrication  of  Leading 
Chemicals,  and  their  Application  to  the  Arts,  Manufac- 
tures, Metallurgy,  and  Agriculture.  By  Prof.  H.  Dus- 
aauce.  (//i  press.) 

7 


PBACTICAL   AND   SCIENTIFIC   BOOKS. 

DYEING,  CALICO  FEINTING,  COLOKS,  COTTON  SPIN- 
NING, AND  WOOLEN  MANUFACTUEE. 

Baird,    The  American  Cotton  Spinner,  and 
Manager's  and  Carder's  Guide; 

A  Practical  Treatise  on  Cotton  Spinning  ;  giving  the  Di- 
mensions and  Speed  of  Machinery,  Draught  and  Twist 
Calculations,  etc.;  with  Notices  of  recent  Improvements  : 
together  with  Rules  and  Examples  for  making  changes 
in  the  sizes  and  numbers  of  Roving  and  Yarn.  Com- 
piled from  the  papers  of  the  late  Robert  H.  Baird. 
12mo $1.25 

Capron  Be  Dole,    Dussauce,    Blues  and  Car- 
mines of  Indigos 

A  Practical  Treatise  on  the  Fabrication  of  every  Commer 
cial  Product  derived  from  Indigo.  By  Felicien  Capron 
de  Dole.  Translated,  with  important  additions,  by  Pro- 
fessor H.  Dussauce.  12mo 


Chemistry  Applied  to  Dyeing, 

By  James  Napier,  F.  C.  S.     Illustrated.    12mo $2.00 

CONTENTS.— General  Properties  of  Matter.— Heat,  Light,  Ele- 
ments of  Matter,  Chemical  Affinity.  Won- Metallic  Substances.— Oxygen, 
Hydrogen,  Nitrogen,  Chlorine,  Sulphur,  Selenium,  Phosphorus,  Iodine, 
Bromine,  Fluorine,  Silicum,  Boron,  Carbon.  Metallic  Substances. — 
General  Properties  of  Metals,  Potassium,  Sodium,  Lithium,  Soap, 
Barium.  Strontium,  Calcium,  Magnesium,  Alminum,  Manganese,  Iron, 
Cobalt,  Nickel,  Zinc,  Cadmium,  Copper,  Lead,  Bismuth,  Tin,  Titanium, 
Chromium,  Vanadium,  Tungstenum  or  Wolfram,  Molybdenum,  Tella- 
rium,  Arsenic,  Antimony,  Uranium,  Cerium,  Mercury.  Silver,  Gold, 
Platinum,  Palladium,  Iridium,  Osmium,  Rhodium,  Lanthanium.  Mor- 
dants.— Red  Spirits,  Barwood  Spirits,  Plumb  Spirits,  Yellow  Spirits, 
Nitrate  of  Iron,  Acetate  of  Alumina,  Black  Iron  Liquor,  Iron  and  Tin 
for  Royal  Blues,  Acetate  of  Copper.  Vegetable  Matters  used,  in  Dyeing. — 
Galls,  Sumach,  Catechu,  Indigo,  Logwood,  Brazil-woods,  Sandal-wood, 
Barwood,  Camwood,  Fustic,  Young  Fustic,  Bark  or  Quercitron,  Fla- 
vine,  Weld  or  Wold,  Turmeric,  Persian  Berries,  Safflower,  Madder, 
Munjeet,  Annota,  Alkanet  Root,  Archil.  Proposed  New  Vegetable 
Dyes.— Sooranjee,  Carajuru,  Wongshy,  Aloes,  Pittacal,  Barbary  Root. 
Animal  Matters  iised  in  Dyeing.— Cochineal,  Lake  or  Lac,  Kerms. 

This  will  be  found  one  of  the  most  valuable  books  on  the  subject  of 
dyeing,  ever  published  in  this  country. 

Dnssauee,    Treatise  on  the  Coloring  Matters 
Derived  from  Coal  Tar; 

Their  Practical  Application  in  Dyeing  Cotton,  Wool,  and 


PUBLISHED  BY  HENRY  CAREY  BAIRD. 

Silk  ;  the  Principles  of  the  Art  of  Dyeing  and  of  the  Dis- 
tillation of  Coal  Tar ;  with  a  Description  of  the  most  Im- 
portant New  Dyes  now  in  use.  By  Professor  H.  Dus- 

sance,  Chemist.     12mo $2.50 

CONTENTS.— Historical  Notice  of  the  Art  of  Dyeing— Chemical 
Principles  of  the  Art  of  Dyeing— Preliminary  Preparation  of  Stufft— 
Mordants — Dyeing — On  the  Coloring  Matters  produced  by  Coal  Tar — 
Distillation  of  Coal  Tar— History  of  Aniline— Properties  of  Aniline- 
Preparation  of  Aniline  directly  from  Coal  Tar— Artificial  Preparation 
of  Aniline— Preparation  of  Benzole— Properties  of  Benzole— Prepara- 
tion of  Nitro-Benzole — Transformation  of  Nitro-Benzole  into  Aniline, 
by  means  of  Sulphide  of  Ammonium  ;  by  Nascent  Hydrogen  ;  by  Ace- 
tate of  Iron ;  and  by  Arsenite  of  Potash— Properties  of  the  Bi-Nitro- 
Benzole— Aniline  Purple—  Violine  — Roseine— Emeraldine—  Bleu  de 
Paris — Futschine,  or  Magenta — Coloring  Matters  obtained  by  other 
bases  from  Coal  Tar—  Is'itroso-Phenyline—  Di  Nitro-Aniline— Nitro- 
Phenyline— Picric  Acid— Rosolic  Acid— Quinoline— Napthaline  Colors 
— Chloroxynaphthalic  and  Perchloroxynapthalic  Acids— Carminaph- 
tha — Ninaphthalamine — Nitrosonaphthaline — Naphthamein — Tar  Red 
— Azuline— Application  of  Coal  Tar  Colors  to  the  Art  of  Dyeing  and 
Calico  Printing— Action  of  Light  on  Coloring  Matters  from  Coal  Tar 
—Latest  Improvements  in  the  Art  of  Dyeing— Chrysammic  Acid— Mo- 
lybdic  and  Picric  Acids— Extract  of  Madder— Theory  of  the  Fixation 
of  Coloring  Matters  in  Dyeing  and  Printing— Principles  of  the  Action 
of  the  most  important  Mordants — Aluminous  Mordants — Ferruginous 
Mordants— Stanniferous  Mordants— Artificial  Alizarin— Metallic  Hy- 
posulphites as  Mordants — Dyer's  Soap — Preparation  of  Indigo  for  Dye- 
ing and  Printing— Relative  Value  of  Indigo — Chinese  Green  Murexlde. 

Dyer  and  Color-maker's  Companion: 

Containing  upwards  of  two  hundred  Receipts  for  making 
Colors,  on  the  most  approved  principles,  for  all  the 
various  styles  and  fabrics  now  in  existence  ;  with  the 
Scouring  Process,  and  plain  Directions  for  Preparing, 
Washing-off,  and  Finishing  the  Goods.  Second  edition, 
lu  one  volume,  12mo 75 


French  Dyer,  (The) 


Comprising  the  Art  of  Dyeing  in  Woolen,  Silk,  Cotton, 
etc.,  etc.  By  M.  M.  Riflaalt,  Vernaud,  De  Fonteuelle, 
Thillaye,  and  Mallepeyre.  (In press.) 

Love,    The  Art  of  Dyeing,  Cleaning,  Sconring, 
and  Finishing, 

ON  THE  MOST  APPROVED  ENGLISH  AND  FRENCH  METHODS  ; 
being  Practical  Instructions  in  Dyeing  Silks,  Woolens 
and  Cottons,  Feathers,  Chips,  Straw,  etc.,  Scouring  and 
Cleaning  Bed  and  Window  Curtains,  Carpets,  Rugs,  etc., 
French  and  English  Cleaning,  any  Color  or  Fabric  of 
Silk,  Satin,  or  Damask.  By  Thomas  Love,  a  working 
Dyer  and  Scourer.  In  one  volume,  12mo $3.00 


PRACTICAL   AND   SCIENTIFIC   BOOKS, 

O'Neill,    Chemistry  of  Calico  Printing,  Dye- 
ing, and  Bleaching ; 

Including  Silken,  Woolen,  and  Mixed  Goods  ;  Practical 
and  Theoretical.  By  Charles  O'Neill.  (In  press.) 

O'Neill,    A  Dictionary  of  Calico  Printing  and 
Dyeing, 

By  Charles  O'Neill.     (In press.) 

Scott,    The  Practical  Cotton-spinner  and  Man- 
ufacturer ; 

OR,  THE  MANAGER  AND  OVERLOOKER'S  COMPANION.  This 
work  contains  a  Comprehensive  System  of  Calculations 
for  Mill  Gearing  and  Machinery,  from  the  first  Moving 
Power,  through  the  different  processes  of  Carding,  Draw- 
ing, Slabbing,  Roving,  Spinning,  and  Weaving,  adapted 
to  American  Machinery,  Practice  and  Usages.  Compen- 
dious Tables  of  Yarns  and  Reeds  are  added.  Illustrated 
by  large  Working-Drawings  of  the  most  approved  Ameri- 
can Cotton  Machinery.  Complete  in  one  volume,  oc- 
tavo  $3.50 

This  edition  of  Scott's  Cotton-Spinner,  by  Oliver  Byrne,  is  designed 
for  the  American  Operative.  It  will  be  found  intensely  practical,  and 
will  be  of  the  greatest  possible  value  to  the  Manager,  Overseer,  and 
Workman. 

Sellers,    The  Color-mixer, 

By  John  Sellers,  an  Experienced  Practical  Workman. 
To  which  is  added  a  CATECHISS*  OP  CHEMISTRY.  In  one 
volume,  12mo.  (In  press.) 

Smith,    The  Dyer's  Instructor; 

Comprising  Practical  Instructions  in  the  Art  of  Dyeing 
Silk,  Cotton,  Wool  and  Worsted,  and  Woolen  Goods,  as 
Single  and  Two-colored  Damasks,  Moreens,  Camlets, 
Lastings,  Shot  Cobourgs,  Silk  Striped  Orleans,  Plain  Or- 
leans, from  White  and  Colored  Warps,  Merinos,  Woolens, 
Yarns,  etc.;  containing  nearly  eight  hundred  Receipts. 
To  which  is  added  a  Treatise  on  the  Art  of  Padding,  and 
the  Printing  of  Silk  Warps,  Skeins  and  Handkerchiefs, 
and  the  various  Mordants  and  Colors  for  the  different 
10 


PUBLISHED  BY  HENRY  CAEEY  BAIRD. 


styles  of  such  work.     By  David   Smith,  Pattern  Dyer. 
A  new  edition,  in  one  volume,  12mo  .....................  $3.00 

CONTENTS.—  Wool  Dyeing,  60  receipts—  Cotton  Dyeing,  68  re- 
ceipts—Silk Dyeing,  60  receipts—  Woolen  Yarn  Dyeing,  69  receipts- 
Worsted  Yarn  Dyeing,  61  receipts  —  Woolen  Dyeing,  52  receipts  —  Da- 
mask Dyeing,  40  receipts—  Moreen  Dyeing,  38  receipts—  Two-Colored 
Damask  Dyeing,  21  receipts—  Camlet  Dyeing,  23  receipts—  Lasting  Dye- 
ing, 23  receipts—  Shot  Cobourg  Dyeing,  18  receipts—  Silk  Striped  Or- 
leans, from  Black,  White,  and  Colored  Warps,  23  receipts—  Colored 
Orleans,  from  Black  Warps,  16  receipts—  Colored  Orleans  and  Co- 
bourgs,  from  White  Warps,  27  receipts  —  Colored  Merinos,  41  receipts 
—Woolen  Shawl  Dyeing,  16  receipts—  Padding,  42  receipts—  Silk  Warp, 


—  ,  —  ,  —  , 

Skein,  and  Handkerchief  Printing,  62  receipts—  Nature  and  Use  of  Dye- 
wares,  including  Alum,  Annotta,  Archil,  Ammonia,  Argol,  Super 
Argol,  Camwood,  Catechu,  Cochineal,  Chrome,  or  Bichromate  of  Pot- 


, ,  ,  ,  ,  - 

ash, Cudbear,  Chemic,  or  Sulphate  of  Indigo,  French  Berry,  or  Persian 
Berry,  Fustic  or  Young  Fustic,  Galls,  Indigo,  Kermes  or  Lac  Dye, 
Logwood,  Madder,  Nitric  Acid  or  Aqua  Fortis,  Nitrates.  Oxalic  Tin, 
Peachwood,  Prussiate  of  Potash,  Quercitron  Bark,  Safflower,  Saun- 
ders  or  Red  Sandal,  Sapan  Wood,  Sumach,  Turmeric,  Examination  of 
Water  by  Tests,  etc.,  etc. 

Toustain,    A  Practical  Treatise  on  the  Woolen 
Manufacture, 

From  the  French  of  M.  Toustain.     (In  press.) 

Ulrich,    Dussauce,    A  Complete  Treatise 

ON  THE  ART  OF  DYEING  COTTON  AND  WOOL,  AS  PRACTISED  m 
PARIS,  ROUEN,  MULHOUSE  AND  GERMANY.  From  the  French 
of  M.  Louis  Ulrich,  a  Practical  Dyer  in  the  principal 
Manufactories  of  Paris,  Rouen,  Mulhouse,  etc.,  etc.  ;  to 
which  are  added  the  most  important  Receipts  for  Dyeing 
Wool,  as  practised  in  the  Manufacture  Iinperiale  des 
Gobelins,  Paris.  By  Professor  H.  Dussauce.  12mo..$3.00 

CONTENTS.- 

Rouen  Dyes,  106  Receipts. 

Alsace        "  235        " 

German     "  109 

M  ii  I  house  "  72        "                             ,     *      - 

Parisian     "  66       " 

Gobelins    "  100       " 
In  all  nearly  700  Receipts. 


Easton,    A  Practical  Treatise  on  Street  or 
Horse-power  Railways; 

Their  Location,  Construction  and  Management ;  with 
general  Plans  and  Rules  for  their  Organization  and  Ope- 
ration ;  together  with  Examinations  as  to  their  Compara- 


FBACTICAL  AND  SCIENTIFIC  BOOKS, 

tive  Advantages  over  the  Omnibus  System,  and  Inquiries 
as  to  their  Value  for  Investment ;  including  Copies  of 
Municipal  Ordinances  relating  thereto.  By  Alexander 
Easton,  C.  E.  Illustrated  by  twenty-three  plates,  8vo., 
cloth $2.00 

Examinations  of  Drugs,  Medicines,  Chemicals, 
etc,, 

As  to  their  Purity  and  Adulterations.  By  C.  H.  Peirce, 
M.  D.  12mo.,  cloth $2.00 

Fisher's  Photogenic  Manipulation, 

IGmo.,  cloth 62 

Gas  and  Ventilation; 

A  Practical  Treatise  on  Gas  and  Ventilation.  By  E.  E. 
Perkins.  12mo.,  cloth 75 

Gilhart,    A  Practical  Treatise  on  Banking, 

By  James  William  Gilbart,  F.  R.  S.  A  new  enlarged  and 
improved  edition.  Edited  by  J.  Smith  Homans,  editor 
of  "  Banker's  Magazine."  To  which  is  added  "Money," 
by  H.  C.  Carey.  8vo $3.00 

Gregory's  Mathematics  for  Practical  Men ; 

Adapted  to  the  Pursuits  of  Surveyors,  Architects,  Me- 
chanics and  Civil  Engineers.  8vo.,  plates,  cloth...$1.50 

flardwich,    A  Manual  of  Photographic  Chem- 
istry; ' 

Including  the  practice  of  the  Collodion  Process.  By  J. 
F.  Hardwich.  (In press.) 

Hay.    The  Interior  Decorator; 

The  Laws  of  Harmonious  Coloring  adapted  to  Interior 
Decorations ;  with  a  Practical  Treatise  on  House  Paint- 
ing. By  D.  R.  Hay,  House  Painter  and  Decorator.  Il- 
lustrated by  a  Diagram  of  the  Primary,  Secondary  and 
Tertiary  Colors.  12mo.  (In press.) 


PUBLISHED  BY  HENBY  CABEY  BAIBD. 

Inventor's  Guide — Patent  Office  and  Patent 
Laws: 

Or,  a  Guide  to  Inventors,  and  a  Book  of  Reference  for 
Judges,  Lawyers,  Magistrates,  and  others.  By  J.  G. 
Moore.  12mo.,  cloth $1.00 

Jervis,    Railway  Property,    A  Treatise 

On  THE  CONSTRUCTION  AND  MANAGEMENT  OF  RAILWAYS  ;  de- 
signed to  afford  useful  knowledge,  in  the  popular  style, 
to  the  holders  of  this  class  of  property ;  as  well  as  Rail- 
way Managers,  Officers  and  Agents.  By  John  B.  Jervis, 
late  Chief  Engineer  of  the  Hudson  River  Railroad,  Cro- 

ton  Aqueduct,  etc.     One  volume,  12mo.,  cloth $1.50 

CONTENTS.  —  Preface  —  Introduction.  Construction.  —  Introduc- 
tory— Land  and  Land  Damages — Location  of  Line — Method  of  Business 
— Grading— Bridges  and  Culverts— Road  Crossings— Ballasting  Track- 
Cross  Sleepers— Chairs  and  Spikes— Rails— Station  Buildings— Loco- 
motives, Coaches  and  Cars.  Operating.— Introductory— Freight—  Pas- 
sengers— Engine  Drivers — Repairs  to  Track — Repairs  of  Machinery — 
Civil  Engineer— Superintendent— Supplies  of  Material— Receipts— Dis- 
bursements —  Statistics  —  Running  Trains  —  Competition  —  Financial 
Management— General  Remarks. 

Johnson,    The  Coal  Trade  of  British  America; 

With  Researches  on  the  Characters  and  Practical  Values 
of  American  and  Foreign  Coals.  By  Walter  R.  Johnson, 

Civil  and  Mining  Engineer  and  Chemist.     8vo $2.00 

This  volume  contains  the  results  of  the  experiments  made  for  the 
Navy  Department,  upon  which  their  Coal  contracts  are  now  based. 

Johnston,    Instructions  for  the  Analysis  of 
Soils,  Limestones  and  Manures, 

By  J.  F.  W.  Johnston.     12mo 38 

Larkin,    The  Practical  Brass  and  Iron  Found- 
er's Guide; 

A  Concise  Treatise  on  the  Art  of  Brass  Founding,  Mould- 
ing, etc.  By  James  Larkin.  12mo.,  cloth $1.00 

Leslie's  (Miss)  Complete  Cookery; 

Directions  for  Gookery  in  its  Various  Branches.  By  Miss 
Leslie.  58th  thousand.  Thoroughly  revised  ;  with  the 
addition  of  New  Receipts.  In  one  volume,  12mo.,  half 

bound,  or  in  sheep $1.00 

13 


PRACTICAL  AND  SCIENTIFIC  BOOKS, 

Leslie's  (Miss)  Ladies'  House  Book; 

A  Manual  of  Domestic  Economy.  20th  revised  edition. 
12mo.,  sheep $1.00 

Leslie's  (Miss)  Two  Hundred  Receipts  in 
French  Cookery, 

Cloth,  12mo 25 

Lieber,    Assayer's  Guide; 

Or,  Practical  Directions  to  Assayers,  Miners  and  Smelters, 
for  the  Tests  and  Assays,  by  Heat  and  by  Wet  Processes, 
of  the  Ores  of  all  the  principal  Metals,  and  of  Gold  and 
Silver  Coins  and  Alloys.  By  Oscar  M.  Lieber,  late  Geolo- 
gist to  the  State  of  Mississippi.  12mo.  With  illustra- 
tions    75 

"  Among  the  indispensable  works  for  this  purpose,  is  this  little 
guide."— Artizan. 

Lowig,    Principles  of  Organic  and  Physiologi- 
cal Chemistry, 

By  Dr.  Carl  Lowig,  Doctor  of  Medicine  and  Philosophy ; 
Ordinary  Professor  of  Chemistry  in  the  University  of 
Zurich  ;  Author  of  "  Chemie  des  Organischen  Verbindun 
gen."  Translated  by  Daniel  Breed,  M.  D.,  of  the  U.  S. 


'atent  Office  ;  late  of  the  Laboratory  of  Li€ 
8vo.,  sheep ~ $3.50 

Marhle  Worker's  Manual; 

Containing  Practical  Information  respecting  Marbles  in 
general,  their  Cutting,  Working  and  Polishing,  Veneer- 
ing, etc.,  etc.  12mo.,  cloth $1.00 

Miles,    A  Plain  Treatise  on  Horse-shoeing, 

With  Illustrations.  By  William  Miles,  Author  of  "  The 
Horse's  Foot." 75 

Morfit,    The  Arts  of  Tanning,  Currying  and 
Leather  Dressing, 

Theoretically  and  Practically  Considered  in  all  their  De- 
tails ;  being  a  Full  and  Comprehensive  Treatise  on  the 


PUBLISHED  BY  HENRY  CAREY  BAIRD. 

Manufacture  of  the  Various  Kinds  of  Leather.  Illus- 
trated by  over  two  hundred  Engravings.  Edited  from  the 
French  of  De  Fontenelle  and  Malapeyere.  With  nu- 
merous Emendations  and  Additions,  by  Campbell  Morfit, 
Practical  and  Analytical  Chemist.  Complete  in  one  vol- 
ume, octavo $10.00 

This  important  Treatise  will  be  found  to  cover  the  whole  field  in 
the  most  masterly  manner,  and  it  is  believed  that  in  no  other  branch 
of  applied  science  could  more  signal  service  be  rendered  to  American 
Manufactures. 

The  publisher  is  not  aware  that  in  any  other  work  heretofore  issued 
in  this  country,  more  space  has  been  devoted  to  this  subject  than  a 
single  chapter  ;  and  in  offering  this  volume  to  so  large  and  intelligent 
a  class  as  American  Tanners  and  Leather  Dressers,  he  feels  confident 
of  their  substantial  support  and  encouragement. 


CONTENTS.— Introduction— Dignity  of  Labor— Tan  and  Tannin 
ining  Materials— Oak  Barks— Barking 
of  Trees— Method  of  Estimating  the  Tanning  Power  of  Astringent 


—Gallic  Acid— Extractive-Tanning  Materials— Oak  Barks— Barkii 


Substances — Tan — The  Structure  and  Composition  of  Skin — Different 
Kinds  of  Skin  suitable  for  Tanning— Preliminary  Treatment  of  Skins 
— Tanning  Process — Improved  Processes — Vauquelin's  Process — Ac- 
celerating Processes— Keasley's,  Trumbull's,  Hibbard's,  and  Leprieur's 
Processes — Tanning  with  Extract  of  Oak-Bark — Hemlock  Tanning — 
With  Myrtle  Plant— English  Harness  Leather-Calf  Skins— Goat  and 
Sheep  Skins— Horse  Hides— Buck.  Wolf  and  Dog  Skins— Buffalo,  or 
"  Grecian"  Leather— Russia  Leather— Red  Skins— Wallachia  Leather 
— Mineral  Tanning — Texture  and  Quality  of  Leather,  and  the  means 
of  Discovering  its  Defects— Tawing— Hungary  Leather— Oiled  Leather 
—Tanning  as  practised  by  the  Mongol  Tartars— Shagreen— Parchment 
—Leather  Bottles— Tanning  of  Cordage  and  Sail  Cloth— Glazed  or 
"Patent"  Leather— Helverson's  Process  for  Rendering  Hides  Hard 
and  Transparent — Currying — Currying  of  Calf  Skins — Currying  of 
Goat  Skins— Red  Leather— Fair  Leather— Water  Proof  Dressing- 
Perkins'  Machine  for  Pommelling  and  Graining  Leather— Splitting, 
Shaving,  Fleshing  and  Cleansing  Machines— Embossing  of  Leather- 
Gut  Dressing. 

Morfit,    A  Treatise  on  Chemistry 

APPLIED  TO  THE  MANUFACTURE  OF  SOAP  AND  CANDLES  ;  being 
a  Thorough  Exposition,  in  all  their  Minutiae,  of  the  prin- 
ciples and  Practice  of  the  Trade,  based  upon  the  most 
recent  Discoveries  in  Science  and  Art.  By  Campbell 
Morfit,  Professor  of  Analytical  and  Applied  Chemistry  in 
the  University  of  Maryland.  A  new  and  improved  edi- 
tion. Illustrated  with  260  Engravings  on  Wood.  Com- 
plete in  one  volume,  large  8vo $6.00 

CONTENTS— CHAPTER  I.  The  History  of  the  Art  and  its  Rela- 
tions to  Science— II.  Chemical  Combination— III.  Alkalies  and  Alka- 
line Earths— IV.  Alkalimentary— V.  Acids— VI.  Origin  and  Composi- 
tion of  Fatty  Matters— VII.  Saponiflable  Fats— Vegetable  Fats— Ani- 
mal Fats— Waxes— VIII.  Action  of  Heat  and  Mineral  Acids  of  Fatty 
Matters— IX.  Volatile  or  Essential  Oils,  and  Resins— X.  The  Proxi- 
mate Principles  of  Fats— Their  Composition  and  Properties— Basic 
Constituents  of  Fats— XI.  Theory  of  Saponiflcation— XII.  Utensils 
Requisite  for  a  Soap  Factory— XIII.  Preparatory  Manipulations  in 
the  Process  of  Making  Soap-Preparation  of  th«  Lyes-XIV.  Hard 


PKACTICAL   AND   SCIENTIFIC   BOOKS, 

Soaps— XV.  Soft  Soaps— XVI.  Soaps  by  the  Cold  Process— XVII.  Sili- 
cuted  Soaps— XVIII.  Toilet  Soaps— XIX.  Patent  Soaps— XX.  Fraud 
and  Adulterations  in  the  Manufacture  of  Soap— XXI.  Candles— XXII. 
Illumination— XXIII.  Philosophy  of  Flame— XXIV.  Raw  Material 
for  Candles— Purification  and  Bleaching  of  Suet— XXV.  Wicks— XXVI. 
Dipped  Candles— XXVII.  Moulded  Candles— XXVIII.  Stearin  Candles 
—XXIX.  Stearic  Acid  Candles—"  Star"  or  "  Adamantine"  Candles— 
Saponitication  by  Lime— Saponiflcation  by  Lime  and  Sulphurous  Acid 
— Saponification  by  Sulphuric  Acid — Saponiflcation  by  the  combined 
action  of  Heat,  Pressure  and  Steam — XXX.  Spermaceti  Candles — 
XXXI.  Wax  Candles— XXXII.  Composite  Candles— XXXIII.  Paraffin 
—XXXIV.  Patent  Candles— XXXV.  Hydrometers  and  Thermometers. 

Mortimer,    Pyrotechnist's  Companion; 

Or,  a  Familiar  System  of  Fire-works.  By  G.  W.  Morti- 
mer. Illustrated  by  numerous  Engravings.  12mo...  75 

Napier,    Manual  of  Electro-Metallurgy; 

Including  the  Application  of  the  Art  to  Manufacturing 
Processes.  By  James  Napier.  From  the  second  London 
edition,  revised  and  enlarged.  Illustrated  by  Engrav- 
ings. In  one  volume,  12mo $1.50 

Napier's  Electro-Metallurgy  is  generally  regarded  as  the  very  best 
Practical  Treatise  on  the  Subject  in  the  English  Language. 

CONTENTS.— History  of  the  Art  of  Electro-Metallurgy— Descrip- 
tion of  Galvanic  Batteries,  and  their  respective  Peculiarities— Elec- 
trotype Processes — Miscellaneous  Applications  of  the  Process  of  Coat- 
ing with  Copper  —  Bronzing  —  Decomposition  of  Metals  upon  one 
another— Electro-Plating— Electro-Gilding— Results  of  Experiments 
on  the  Deposition  of  other  Metals  as  Coatings,  Theoretical  Observa- 
tions. 

Norris' s  Hand-book  for  Locomotive  Engineers 
and  Machinists; 

Comprising  the  Calculations  for  Constructing  Locomo- 
tives, Manner  of  setting  Valves,  etc.,  etc.  By  Septimus 
Norris,  Civil  and  Mechanical  Engineer.  In  one  volume 

12mo.,  with  Illustrations $1.50 

"With  pleasure  do  we  meet  with  such  a  work  as  Messrs.  Norris 
and  Baird  have  given  us."— Artizan. 

"In  this  work  he  has  given  us  what  are  called  'the  secrets  of  the 
business,'  in  the  rules  to  construct  locomotives,  in  order  that  the  mil- 
lion should  be  learned  in  all  things."— Scientific  American. 

Nystrom,   A  Treatise  on  Screw-Propellers  and 
their  Steam-Engines; 

With  Practical  Rules  aud  Examples  by  which  to  Calcu- 
late and  Construct  the  same  for  any  description  of  Ves- 
sels. By  J.  W.  Nystrom.  Illustrated  by  over  thirty 
large  Working  Drawings.  In  one  volume,  octavo. ..§3.50 


PUBLISHED  BY  HENBY  CABBY  BAIRD. 

Overman,    The  Manufacture  of  Iron  in  all  its 
Various  Branches; 

To  which  is  added  an  Essay  on  the  Manufacture  of  Steel. 
By  Frederick  Overman,  Mining  Engineer.  With  one 
hundred  and  fifty  Wood  Engravings.  Third  edition.  In 

one  volume,  octavo,  five  hundred  pages $6.00 

"  We  have  now  to  announce  the  appearance  of  another  valuable 
work  on  the  subject,  which,  in  our  humble  opinion,  supplies  any  defi- 
ciency which  late  improvements  and  discoveries  may  have  caused, 
from  the  lapse  of  time  since  the  date  of  '  Mushet'  and  '  Schrivenor.' 
It  is  the  production  of  one  of  our  Trans- Atlantic  brethren,  Mr.  Fred- 
erick Overman,  Mining  Engineer  ;  and  we  do  not  hesitate  to  set  it 
down  as  a  work  of  great  importance  to  all  connected  with  the  iron  in- 
terests :  one  which,  while  it  is  sufficiently  technological  fully  to  ex- 
plain chemical  analysis,  and  the  various  phenomena  of  iron  under 
different  circumstances,  to  the  satisfaction  of  the  most  fasticlious;  is 
written  in  that  clear  and  comprehensive  style  as  to  be  available  to  the 
capacity  of  the  humblest  mind,  and  consequently  will  be  of  much  ad- 
vantage to  those  works  where  the  proprietors  may  see  the  desirability 
of  placing  it  in  the  hands  of  their  operatives." — London  Mining 
Journal. 

Painter,  Gilder  and  Varnisher's  Companion; 

Containing  Rules  and  Regulations  in  every  thing  relating 
to  the  Arts  of  Painting,  Gilding,  Varnishing  and  Glass 
Staining  ;  with  numerous  useful  and  valuable  Receipts  ; 
Tests  for  the  detection  of  Adulterations  in  Oils  and 
Colors  ;  and  a  statement  of  the  Diseases  and  Accidents  to 
which  Painters,  Gilders  and  Varnishers  are  particularly 
liable,  with  the  simplest  methods  of  Prevention  and 
Pwemedy.  Eighth  edition.  To  which  are  added  Complete 
Instructions  in  Graining,  Marbling,  Sign  Writing,  and 
Gilding  on  Glass.  12mo.,  cloth 75 

Paper-Hanger's  (The)  Companion; 

In  which  the  Practical  Operations  of  the  Trade  are  sys- 
tematically laid  down  ;  with  copious  Directions  Prepara- 
tory to  Papering  ;  Preventions  against  the  effect  of  Damp 
in  Walls  ;  the  various  Cements  and  Pastes  adapted  to 
the  several  purposes  of  the  Trade  ;  Observations  and  Di- 
rections for  the  Panelling  and  Ornamenting  of  Rooms, 
etc.,  etc.  By  James  Arrowsmith.  In  one  volume, 
12mo 75 

Practical  (The)  Surveyor's  Guide; 

Containing  the  necessary  information  to  make  any  per- 
non  of  common  capacity  a  finished  Land  Surveyor,  with- 

17 


PRACTICAL   AND    SCIENTIFIC   BOOKS, 

out  the  aid  of  a  Teacher.     By  Andrew  Duncan,  Land 

Surveyor  and  Civil  Engineer.  .  12mo 75 

Having  had  an  experience  as  a  Practical  Surveyor,  etc.,  of  thirty 
years,  it  is  believed  that  the  author  of  this  volume  possesses  a  thorough 
knowledge  of  the  wants  of  the  profession  ;  and  never  having  met  with 
any  work  sufficiently  concise  and  instructive  in  the  several  details 
necessary  for  the  proper  qualification  of  the  Surveyor,  it  has  been  his 
object  to  supply  that  want.  Among  other  important  matters  in  the 
book,  will  be  found  the  following : 


Instructions  in  levelling  and  profiling,  with  a  new  and  speedy  plan 
f  setting  grades  on  rail  and  plank  roads— the  method  of  inflecting 
curves — the  description  and  design  of  a  new  instrument,  whereby  dis- 


tances are  found  at  once,  without  any  calculation — a  new  method  of 
surveying  any  tract  of  land  by  measuring  one  line  through  it — a  geo- 
metrical method  of  correcting  surveys  taken  with  the  compass,  to  fit 
them  for  calculation — a  short  method  of  finding  the  angles  from  the 
courses,  and  vice  versa — the  method  of  surveying  with  the  compass 
through  any  mine  or  iron  works,  and  to  correct  the  deflections  of  the 
needle  by  attraction— description  of  an  instrument  by  the  help  of 
which  any  one  may  measure  a  map  by  inspection,  without  calculation 
— a  new  and  short  method  of  calculation,  wherein  fewer  figures  are 
used— the  method  of  correcting  the  diurnal  variation  of  the  needle 
— various  methods  of  plotting  and  embellishing  maps — the  most  cor- 
rect method  of  laying  off  plots  with  the  pole,  etc.— description  of  a 
new  compass  contrived  by  the  author,  etc.,  etc. 

Railroad  Engineer's  Pocket  Companion  for  the 
Field, 

By  W.  Griswold.     12mo.,  tucks $1.00 

Riddell,    The  Elements  of  Hand-Railing; 

Being  the  most  Complete  and  Original  Exposition  of  this 
Branch  of  Carpentry  that  has  appeared.  By  Robert 
Riddell.  Third  edition.  Enlarged  and  improved.  Il- 
lustrated by  22  large  plates.  4to.,  cloth $3.00 

Rural  Chemistry; 

An  Elementary  Introduction  to  the  Study  of  the  Science, 
in  its  relation  to  Agriculture  and  the  Arts  of  Life.  By 
Edward  Solly,  Professor  of  Chemistry  in  the  Horticul- 
tural Society  of  London.  From  the  third  improved  Lon- 
don edition.  12mo $1.25 

Shunk,    A  Practical  Treatise 

ON  RAILWAY  CURVES,  AND  LOCATION  FOB  YOUNG  ENGINEERS. 
By  Wm.  F.  Shunk,  Civil  Engineer.  12mo $1.0(3 

Strength  and  Other  Properties  of  Metals; 

Reports  of  Experiments  on  the  Strength  and  other  Pro- 


\ 
PUBLISHED  BY  HENRY  CAREY  BAIRD. 

perties  of  Metals  for  Cannon.  With  a  Description  of  the 
Machines  for  Testing  Metals,  and  of  the  Classification  of 
Cannon  in  service.  By  Officers  of  the  Ordnance  Depart- 
ment U.  S.  Army.  By  authority  of  the  Secretary  of 
War.  Illustrated  by  25  large  steel  plates.  In  one  vol- 
ume, quarto $10.00 

The  best  Treatise  on  Cast-iron  extant. 

Tables  Showing  the  Weight 

OF  ROCND,  SQUARE  AND  FLAT  BAR  IKOW,  STEEL,  etc.,  by 
Measurement.  Cloth 50 

Taylor,    Statistics  of  Coal; 

Including  Mineral  Bituminous  Substances  employed  in 
Arts  and  Manufactures  ;  with  their  Geographical,  Geo- 
logical and  Commercial  Distribution,  and  Amount  of  Pro- 
duction and  Consumption  on  the  American  Continent. 
With  Incidental  Statistics  of  the  Iron  Manufacture.  By 
R.  C.  Taylor.  Second  edition,  revised  by  S.  S.  Halde- 
man.  Illustrated  by  five  Maps  and  many  Wood  Engrav- 
ings. 8vo.,  cloth $6.00 

Templeton,     The  Practical  Examinator  on 
Steam  and  the  Steam  Engine ; 

With  Instructive  References  relative  thereto,  arranged 
for  the  use  of  Engineers,  Students,  and  others.  By  Wm. 
Templeton,  Engineer.  12mo 75 

This  work  was  originally  written  for  the  author's  private  use.  He 
was  prevailed  upon  by  various  Engineers,  who  had  seen  the  notes,  to 
consent  to  its  publication,  from  their  eager  expression  of  belief  that 
it  would  be  equally  useful  to  them  as  it  had  been  to  himself. 

Tin  and  Sheet  Iron  Worker's  Instructor; 

Comprising  complete  Descriptions  of  the  necessary  Pat- 
terns and  Machinery,  and  the  Processes  of  Calculating 
Dimensions,  Cutting,  Joining,  Raising,  Soldering,  etc., 
etc.  With  numerous  Illustrations.  (In  press.) 

Treatise  (A)  on  a  Box  of  Instruments, 

And  the  Slide  Rule  ;  with  the  Theory  of  Trigonometry 
and  Logarithms,  including  Practical  Geometry,  Survey 
ing,  Measuring  of  Timber,  Cask  and  Malt  Gauging, 

19 


PEACTICAL  AND  SCIENTIFIC  BOOKS, 

Heights  and  Distances.     By  Thomas   Kentish.     In  one 

volume,  12mo $1.00 

A  volume  of  inestimable  value  to  Engineers,  Gaugers,  Students,  and 
others. 

Turnkll,    The  Electro-Magnetic  Telegraph; 

With  an  Historical  Account  of  its  Rise,  Progress,  and 
Present  Condition.  Also,  Practical  Suggestions  in  regard 
to  Insulation  and  Protection  from  the  Effects  of  Light- 
ning. Together  with  an  Appendix  containing  several 
important  Telegraphic  Devices  and  Laws.  By  Lawrence 
Turnbull,  M.  D.,  Lecturer  on  Technical  Chemistry  at  the 
Franklin  Institute.  Second  edition.  Revised  and  im- 
proved. Illustrated  by  numerous  Engravings.  8vo..§2.00 

Turner's  (The)  Companion; 

Containing  Instruction  in  Concentric,  Elliptic  and  Eccen- 
tric Turning ;  also  various  Steel  Plates  of  Chucks,  Tools 
and  Instruments  ;  and  Directions  for  Using  the  Eccentric 
Cutter,  Drill,  Vertical  Cutter  and  Rest ;  with  Patterns 
and  Instructions  for  working  them.  12mo.,  cloth 75 

Bell,    Carpentry  Made  Easy; 

Or,  The  Science  and  Art  of  Framing,  on  a  New  and  Im- 
proved System  ;  with  Specific  Instructions  for  Building 
Balloon  Frames,  Barn  Frames,  Mill  Frames,  Warehouses, 
Church  Spires,  etc.  ;  comprising  also  a  System  of  Bridge 
Building  ;  with  Bills,  Estimates  of  Cost,  and  Valuable 
Tables.  Illustrated  by  38  plates,  comprising  nearly  200 
figures.  By  William  E.  Bell,  Architect  and  Practical 
Builder.  8vo $3.60 


SOCIAL  SCIENCE. 

THE  WORKS  OF  HENRY  C.  CAREY. 


I  challenge  the  production  from  among  the  writers  on  political 
economy  of  a  more  learned,  philosophical,  and  convincing  speculator 
on  that  theme,  than  my  distinguished  fellow-citizen,  Henry  C.  Carey. 
^«WtK?  ?  has  Publishe<l  in  support  of  the  protective  policy,  are 
remarkable  for  profound  research,  extensive  range  of  inquiry,  rare 
logical  acumen,  and  a  consummate  knowledge  of  history."— Speech  of 

fc^iilf  %££*' in  the  House  of  Rew™Mi™  °f tlie  v*&* 


PUBLISHED  BY  HENRY  CAREY  BAIBD. 
THE  WORKS  OF  HENRY  C.  CAREY. 

"  Henry  C.  Carey,  the  best  known  and  ablest  economist  of  North 
America.  *  *  *  *  *  In  Europe  he  is  principally  known  by  his 
striking  and  original  attacks,  based  upon  the  peculiar  advantages  of 
American  experience,  on  some  of  the  principal  doctrines,  especially 
Malthas'  '  Theory  of  Population'  and  Ricardo's  teachings.  His  views 
have  been  largely  adopted  and  thoroughly  discussed  in  Europe." — 
"  The  German  Political  Lexicon,"  Edited  by  Bluntscfdi  and  Brater.  Leipsic. 
1868. 

"  We  believe  that  your  labors  mark  an  era  in  the  science  of  political 
economy.  To  your  researches  and  lucid  arguments  are  we  indebted 
for  the  explosion  of  the  absurdities  of  Malthus,  Say,  and  Ricardo,  in 
regard  to  the  inability  of  the  earth  to  meet  the  demands  of  a  growing 
population.  American  industry  owes  you  a  debt  which  cannot  be  re- 
paid, and  whichit  will  ever  be  proud  to  acknowledge.— From  a  Letter 
of  Hon.  George  W.  Scranton,  M.  C.,  Hon.  William  Jessup,  and  over  sixty 
influential  citizens  of  Luzerne  County,  Pennsylvania,  to  Henry  C.  Carey, 
April  3,  1859. 

Financial  Crises; 

Their  Causes  and  Effects.     8vo.,  paper 25 

French  and  American  Tariffs, 

Compared  in  a  Series  of  Letters  addressed  to  Mons.  M. 
Chevalier.  8vo.,  paper 15 

Harmony  (The)  of  Interests; 

Agricultural,    Manufacturing    and    Commercial.      8vo., 

paper 75 

Cloth $1.25 

"  We  can  safely  recommend  this  remarkable  work  to  all  who  wish 
to  investigate  the  causes  of  the  progress  or  decline  of  industrial  com- 
munities."— Blackwood's  Magazine. 

Letters  to  the  President  of  the  United  States, 

8vo.,  Paper 50 

Miscellaneous  ¥orks; 

Comprising  "Harmony  of  Interests,"  "Money,"  "Let- 
ters to  the  President,"  "French  and  American  Tariffs," 
and  "  Financial  Crises."  One  volume,  8vo.,  half  bound. 

$2.25 


Money;  A  Lecture 


Before  the  New  York  Geographical  and  Statistical  So- 
ciety.    8vo.,  paper 15 


PBACTICAL  AND  SCIENTIFIC  BOOKS, 
THE  WORKS  OF  HENRY  C.  CAREY. 

Past  (The),  the  Present,  and  the  Future, 

8vo  ....................  .  .............................................  $2.00 

12mo  .................................................................  $1.25 

"  Full  of  important  facts  bearing  on  topics  that  are  now  agitating 
all  Europe.  *  •  *  These  quotations  will  only  whet  the  appetite 
of  the  scientific  reader  to  devour  the  whole  work.  It  is  a  book  full  of 
valuable  information."  —  Economist. 

"  Decidedly  a  book  to  be  read  by  all  who  take  an  interest  in  the  pro- 
gress of  social  science."—  Spectator. 

"A  Southern  man  myself,  never  given  to  tariff  doctrines,  I  confess  to 
have  been  convinced  by  his  reasoning,  and,  thank  Heaven,  have  not 


now  to  learn  the  difference  between  dogged  obstinacy  and  consistency. 
Ye  gods,  give  us  but  light  !'  should  be  the  motto  of  every  inquirer 
fter  truth,  but  for  far  different  and  better  purposes  than  that  which 


prompted  the  exclamation."—  The  late  John  S.  Skinner. 

"  A  volume  of  extensive  information,  deep  thought,  high  intelli- 
gence, and  moreover  of  material  utility."  —  London  Morning  Advertiser. 

"  Emanating  from  an  active  intellect,  remarkable  for  distinct  views 
and  sincere  convictions."  —  Britannia. 

"  '  The  Past,  Present,  and  Future,'  is  a  vast  summary  of  progressive 
philosophy,  wherein  he  demonstrates  the  benefit  of  political  economy 
In  the  onward  progress  of  mankind,  which,  ruled  and  directed  by  over- 
whelming influences  of  an  exterior  nature,  advances  little  by  little, 
until  these  exterior  influences  are  rendered  subservient  in  their  turn, 
to  increase  as  much  as  possible  the  extent  of  their  wealth  and  riches." 
—  Dictionnaire  Universel  des  Contemporains.  Par  G.  Vapereau.  Paris, 
1868. 

Principles  of  Social  Science, 

Three  volumes,  8vo.,  cloth  ..................................  $7.50 

CONTENTS.—  Volume  I.  Of  Science  and  its  Methods—  Of  Man, 
the  Subject  of  Social  Science—  Of  Increase  in  the  Numbers  of  Mankind 
—Of  the  Occupation  of  the  Earth—  Of  Value—  Of  Wealth—  Of  the  For- 
mation of  Society—  Of  Appropriation—  Of  Changes  of  Matter  in  Place 
—Of  M  hanical  and  Chemical  Changes  in  the  Forms  of  Matter.  Vol- 
ume II.  Of  Vital  Changes  in  the  Form  of  Matter—  Of  the  Instrument 
of  Assoc-ation.  Volume  III.  Of  Production  and  Consumption—  Of 
Aecumulation—  Of  Circulation—  Of  Distribution—  Of  Concentration 
and  Centralization—  Of  Competition—  Of  Population—  Of  Food  and 
Population—  Of  Colonization—  Of  the  Malthusian  Theory—  Of  Com- 
merce-Of  the  Societary  Organization—  Of  Social  Science. 

"  I  have  no  desire  here  to  reproach  Mr.  Malthus  with  the  extreme 
lightness  of  his  scientific  baggage.  In  his  day,  biology,  animal  and 
vegetable  chemistry,  the  relations  of  the  various  portions  of  the  hu- 
man organism,  etc.  etc.,  had  made  but  little  progress,  and  it  is  to  the 

ineral  ignorance  in  reference  to  these  questions  that  we  must,  as  I 
think,  look  for  explanation  of  the  fact  that  he  should,  with  so  much 
onfidence,  in  reference  to  so  very  grave  a  subject,  have  ventured  to 
suggest  a  formula  BO  arbitrary  in  its  character,  and  one  whose  hollow- 
ness  becomes  now  so  clearly  manifest.  Mr.  Carey's  advantage  over 
nro^  P  VU0  fact8  and  logic'is  Certainly  due  in  great  part  to  the 
progress  that  has  smce  been  made  in  all  the  sciences  connected  with 
it  then,  how  admirably  has  he  profited  of  them  !  How  entirely 
is  he  au^ourant  of  all  these  branches  of  knowledge  which,  whether 


PUBLISHED  BY  HENRY  CARE'S   BAIRD. 
THE  WORKS  OF  HENRY  C.  CAREY. 

directly  or  indirectly,  bear  upon  his  subject  1  With  what  skill  does  he 
ask  of  each  and  every  of  them  all  that  it  can  be  made  to  furnish, 
whether  of  facts  or  arguments !  With  what  elevated  views,  and 
what  amplitude  of  means,  does  he  go  forward  in  his  work  !  Above 
all,  how  thorough  in  his  scientific  caution  !  Accumulating  inductions, 
and  presenting  for  consideration  facts  the  most  undoubted  and  proba- 
bilities of  the  highest  kind,  he  yet  affirms  nothing,  contenting  himself 
with  showing  that  his  opponent  had  no  good  reason  for  affirming  the 
nature  of  the  progression,  nor  the  time  of  duplication,  nor  the  gene- 
ralization which  takes  the  facts  of  an  individual  case  and  deduces 
from  them  a  law  for  every  race,  every  climate,  every  civilization, 
every  condition,  moral  or  physical,  permanent  and  transient, 
healthy  or  unhealthy,  of  the  various  populations  of  the  many  coun- 
tries of  the  world.  Then,  having  reduced  the  theory  to  the  level  of  a 
mere  hypothesis,  he  crushes  it  to  atoms  under  the  weight  of  facts."— 
M.  De  Fontenay  in  the  "Journal  des  Economistes."  Paris,  September,  1862. 

"  This  book  is  so  abundantly  full  of  notices,  facts,  comparisons,  cal- 
culations, and  arguments,  that  too  much  would  be  lost  by  laying  a 
Eart  of  it  before  the  eye  of  the  reader.  The  work  is  vast  and  severe 
a  its  conception  and  aim,  and  is  far  removed  from  the  common  run 
of  the  books  on  similar  subjects."— 11  Hondo  Letterario,  Turin. 

"  In  political  economy,  America  is  represented  by  one  of  the 
strongest  and  most  original  writers  of  the  age,  Henry  C.  Carey,  of 
Philadelphia.  **********# 

"  His  theory  of  Rents  is  regarded  as  a  complete  demonstration  that 
the  popular  views  derived  from  Ricardo  are  erroneous  ;  and  on  the 
subject  of  Protection,  he  is  generally  confessed  to  be  the  master- 
thinker  of  his  country." — Westminster  Review. 

".  Both  in  America  and  on  the  Continent,  Mr.  Henry  Carey  has  ac- 
quired a  great  name  as  a  political  economist.  *  *  *  *  * 

"  His  refutation  of  Malthus  and  Ricardo  we  consider  most  triumph- 
ant."— London  Critic. 

"  Mr.  Carey  began  his  publication  of  Principles  twenty  years  ago  ; 
he  is  certainly  a  mature  and  deliberate  writer.  More  than  this,  he  is 
readable :  his  pages  swarm  wHh  illustrative  facts  and  with  American 
instances.  ••»»»•»»•*•• 

"  We  are  in  great  charity  with  books  which,  like  Mr.  Carey's,  theo- 
rize with  excessive  boldness,  when  the  author,  as  does  Mr.  Carey, 
possesses  information  and  reasoning  power." — London  Athenteum. 

"  Those  who  would  fight  against  the  insatiate  greed  and  unscrupu- 
lous misrepresentations  of  the  Manchester  school,  which  we  have  fre- 
quently exposed,  without  any  of  their  organs  having  ever  dared  to 
make  reply,  will  find  in  this  and  Mr.  Carey's  other  works  an  immense 
store  of  arms  and  ammunition.  ******** 

"  An  author  who  has,  among  the  political  economists  of  Germany 
and  France,  numerous  readers,  is  worth  attentive  perusal  in  Eng- 
land."—London  Statesman. 

"  Of  all  the  varied  answers  to  the  old  cry  of  human  nature, '  Who 
will  show  us  any  goodl'  none  are  more  sententious  than  Mr.  Carey's. 
He  says  to  Kings,  Presidents,  and  People, '  Keep  the  nation  at  work, 
and  the  greater  the  variety  of  employments  the  better.'  He  is  seek- 
ing and  elucidating  the  great  radical  laws  of  matter  as  regards  man. 
He  is  at  once  the  apostle  and  evangelist  of  temporal  righteousness." 
—National  Intelligencer. 

"  A  work  which  we  believe  to  be  the  greatest  ever  written  by  an 
American,  and  one  which  will  in  future  ages  be  pointed  out  as  the 
most  successful  effort  of  its  time  to  form  the  great  tcientia  scientiarvm." 
—Pkiladelphi-i  Evening  Bulletin. 


PBACTICAL   AND    SCIENTIFIC   BOOKS, 
THE  WORKS  OF  HENRY  C.  CAREY. 

The  Slave  Trade,  Domestic  and  Foreign; 

Why  it  Exists,  and  How  it  may  be  Extinguished.    12mo., 
cloth  .................................................................  $1.25 

CONTENTS.—  The  Wide  Extent  of  Slavery—  Of  Slavery  in  the 
British  Colonies—  Of  Slavery  in  the  United  States—  Of  Emancipation 
in  the  British  Colonies  —  How  Man  passes  from  Poverty  and  Slavery 
toward  Wealth  and  Freedom  —  How  Wealth  tends  to  Increase  —  How 
Labor  acquires  Value  and  Man  becomes  Free—  How  Man  passes  from 
Wealth  and  Freedom  toward  Poverty  and  Slavery  —  How  Slavery 
grew,  and  How  it  is  now  maintained  in  the  West  Indies  —  How  Slavery 
grew,  and  is  maintained  in  the  United  States  —  How  Slavery  grows  in 
Portugal  and  Turkey—  How  Slavery  grows  in  India—  How  Slavery 


grows  in  Ireland  and  Scotland  —  How  Slavery  grows  in  England  — 
How  can  Slavery  be  extinguished?  —  How  Freedom  grows  in  Northern 
Germany—  How  Freedom  grows  in  Russia—  How  Freedom  grows  in 


Denmark—  How  Freedom  grows  in  Spain  and  Belgium—  Of  the  Duty 
of  the  People  of  the  United  States—  Of  the  Duty  of  the  People  of  Eng- 
land. 

"  As  a  philosophical  writer,  Mr.  Carey  is  remarkable  for  the  union 
of  comprehensive  generalizations  with  a  copious  induction  of  facts. 
His  research  of  principles  never  leads  him  to  the  neglect  of  details  ; 
jior  is  his  accumulation  of  instances  ever  at  the  expense  of  universal 
truth.  He  is,  doubtless,  intent  on  the  investigation  of  la-ws,  as  the 
appropriate  aim  of  science,  but  no  passion  for  theory  seduces  him 
Into  the  region  of  pure  speculation.  His  mind  is  no  less  historical 
than  philosophical,  and  had  he  not  chosen  the  severer  branch  in 
which  his  studies  have  borne  such  excellent  fruit,  he  would  have 
attained  an  eminent  rank  among  the  historians  from  whom  the  litera- 
ture of  our  country  has  received  such  signal  illustration."—  New  York 
Tribune. 


French  Politico-Economic  Controversy, 

Between  the  Supporters  of  the  Doctrines  of  CAEET  and 
of  those  of  RICARDO  and  MAI/THUS.  By  MM.  De  Fontenay, 
Dupuit,  Baudrillart,  and  others.  Translated  from  the 
"Journal  des  Economistes,"  1862-63.  (In press.) 

Protection  of  Home  Labor  and  Home  Produc- 
tions 

Necessary  to  the  Prosperity  of  the  American  Farmer. 
By  H.  C.  Baird.  Paper 13 

Smith,    A  Manual  of  Political  Economy, 

By  E.  PesMne  Smith.     12mo.,  cloth $1.25 

24 


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